2009 Florida Beef Research Report

Transcription

2009 Florida Beef
Research Report
Department of Animal
Sciences
ACKNOWLEDGEMENTS
Appreciation is expressed to the following companies, associations, or agencies that provided
grant support for research in the beef cattle program.
Adisseo, Acworth, GA
Alltech, Nicholasville, KY
Bar-L Ranch, Marianna, FL
Central Beef, Bushnell, FL
Elanco, Greenfield, IN
Flint River Mills, Bainbridge, GA
Florida & Georgia Peanut Check-Off
Florida Peanut Producer Association
Hardee Farms, Chiefland, FL
Intervet, Millsboro, DE
IVX Animal Health, St. Joseph, MO
Lakeland Animal Nutrition, Lakeland, FL
Merial Limited, Athens, GA
Orange Hill Soil Conservation District, Chipley, FL
Pfizer Animal Health, New York, NY
Schering-Plough, Kenilworth, NJ
Southeastern Minerals, Inc., Bainbridge, GA
USDA, Washington, DC
US Sugar Corporation, Clewiston, FL
Water Environment Research Foundation, Alexandria, VA
Appreciation is also expressed to the following laboratories, research technicians, unit managers
and crew involved in the research programs at several locations.
Animal Sciences Meats Processing Center
Bryon Davis
Tommy Estevez
Larry Eubanks
College of Veterinary Medicine
Dr. Owen Rae
Forage Evaluation Support Laboratory
Nancy Carter
Richard Fethiere
Beef Research Unit
Roger Barber
Danny Driver
Brian Faircloth
STARS, Brooksville
Lee Adams
Ed Bowers
Eugene Rooks
Myra Rooks
Boston Farm – Santa Fe River Ranch
Jamie Bradley
Steve Chandler
Bert Faircloth
Jerry Wasdin
NFREC, Marianna
Wayne Branch
Meghan Brennan
Mary Chambliss
John Crawford
Tina Gwin
Brook Hand
Don Jones
Jeff Jones
Todd Matthews
Charles Nowell
Harvey Standland
Animal Sciences Technicians
Pam Miles
Frank Robbins
Sergei Sennikov
Reyna Speckman
Nancy Wilkinson
Beef Teaching Unit
Jesse Savell
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Table of Contents
Management
Water Intake and Factors Affecting Water Intake of Growing
Beef Cattle in North Florida ......................................................................................1
Characterization of the Acute-Phase Protein Response Following
Vaccination and Weaning in Beef Steers.................................................................. 5
Effects of Acclimation to Handling on Performance, Reproductive, and
Physiological Responses of Brahman-crossbred Heifers ....................................... 13
Effects of Excitable Temperament and its Physiological Consequences
on Reproductive Performance of Brahman-crossbred Cows .................................. 19
Reproduction
Effects of Day of Cycle at Initiation of a Select Synch/CIDR + Timed-artificial
Insemination Protocol in Suckled Angus and Brangus Cows ................................ 27
Evaluation of a New or Once-used CIDR and Two Different Prostaglandin
F2 Treatments to Synchronize Suckled Bos indicus Bos taurus Cows ............. 37
Comparison of a Select Synch/CIDR + Timed Artificial Insemination
vs a Modified Co-Synch/CIDR Estrous Synchronization
Protocol in Suckled Bos indicus Bos taurus Cows .............................................. 47
Comparison of Two Progestogen Based Estrous Synchronization Protocols
and Cloprostenol Sodium vs. Dinoprost Tromethamine in Suckled Post
Partum Cows and Yearling Heifers of Bos indicus × Bos taurus Breeding........... 55
Effectiveness of Cloprostenol Sodium vs. Dinoprost Tromethamine
in a GnRH/CIDR + PGF2α Synchronization Protocol in Angus,
Brahmans, and Brahman Angus Cows ................................................................ 63
Presynchronization of Suckled Beef Cows with Human Chorionic
Gonadotropin (hCG) 7 days Prior to Initiation of a Fixed-time Artificial
Insemination Protocol Fails to Enhance Fertility.................................................... 69
Nutrition – Meat
Effect of Optaflexx® 45 (Ractopamine-HCl) on Live and Carcass
Performance when Fed to Steers During the Final 28 Days of Feeding ................ 77
Nutrition – Supplements
Evaluation of Whole, In-Shell Peanuts as a Supplement Feed for Beef Cows................... 83
http://www.animal.ufl.edu/extension/beef/pubs.shtml
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Table of Contents
Co-product and Rumen Degradable Protein Supplementation of Beef
Steers Fed Bahiagrass Forage ................................................................................. 91
Dried Distillers Grains and(or) Soybean Hulls to Background Beef
Calves Fed Bahiagrass Forage ................................................................................ 97
Feeding Interval Effects on Growth, Puberty, and Pregnancy Rates in
Yearling Bos indicus and Bos taurus Beef Heifers .............................................. 103
Programmed Feeding Effects on Growth, Puberty, and Pregnancy Rates
in Yearling Bos indicus and Bos taurus Beef Heifers .......................................... 107
Nutrition – Minerals/Vitamins
Mineral Concentrations of Cool-Season Pasture Forages in North Florida during the
Winter-Spring Grazing Season: I. Macro Minerals .............................................. 111
Mineral Concentrations of Annual Cool Season Pasture Forages in North Florida
during the Winter-Spring Grazing Season: II. Trace Minerals ........................... 117
Effects of Aluminum (Al) from Water Treatment Residual Applications
to Pastures on Mineral Status of Grazing Cattle and Mineral
Concentrations of Forages .................................................................................... 123
Methods of Selenium Supplementation to Beef Cows on Blood, Liver and
Milk Selenium Concentrations ............................................................................. 129
Comparing Tolerance of Selenium (Se) as Sodium Selenite or Se Yeast on
Blood and Tissue Se Concentrations of Ruminants .............................................. 135
Bioavailability of Vitamin A (Retinol) Sources for Cattle ............................................... 141
Forages
Forage Nutritional Quality Evaluation of Bahiagrass Selections ..................................... 145
Warm-Season Legume Hay or Soybean Meal Supplementation Effects
on The Performance of Lambs ............................................................................. 149
Warm-Season Legume Haylage or Soybean Meal Supplementation Effects
on the Performance of Lambs ............................................................................... 153
Annual Legumes to Complement Warm-Season Perennial Grass Forage
Systems in North Florida ...................................................................................... 157
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Table of Contents
Case Study: Evaluation of Annual Cultivated Peanut as a Forage Crop
for Grazing by Growing Beef Cattle .................................................................... 163
Effects of Forage Sampling Method on Nutritive Value of Bahiagrass
During The Summer and Fall ............................................................................... 169
Effects of Forage Sampling Method on Nutritive Value of Bahiagrass
During the Winter and Spring ............................................................................... 175
The use of trade names in this publication is solely for the purpose of providing specific information.
UF/IFAS does not guarantee or warranty the products named, and references to them in this
publication does not signify our approval to the exclusion of other products of suitable composition.
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Water Intake and Factors Affecting Water Intake of Growing Beef Cattle in
North Florida
Megan Brew1
Bob Myer
Jeff Carter
Matt Hersom
Gary Hansen
Water intake and the factors that affect water intake in growing beef were studied using a continuous
data acquisition system. Water intake was positively correlated with average daily gain but had no
relationship to feed efficiency. Established prediction equations were found to overestimate water intake
Summary
A study was conducted to measure water intake
in growing beef cattle, to determine what factors
influence, and are influenced by, water
consumption, and to compare observed intakes
to predicted intakes. Growing bulls, steers, and
heifers (n=146; average starting weight of 607
lb) were housed in an open sided barn for a
period of 13 wk from Sep 2006 through Dec
2006. Feed and water intake data was
continually monitored by GrowSafe hardware
and software. Cattle were weighed weekly.
Mean water intake was 7.92 gal/d per heady or
an average of 0.007 gal/lb of metabolic body
weight (BW). Cattle of Brahman and
Romosinuano breeding tended to consume less
water than British and Continental influenced
cattle at the same metabolic BW (P<0.05).
There was no difference among bulls, steers,
and heifers in either gross water intake or water
intake per lb of metabolic BW. The mean daily
temperature remained within the thermal neutral
zone throughout the study and had no influence
on water intake. Water intake was positively
correlated (P<0.05) with feed intake and weight
gain. There was no relationship between water
intake and gain-to-feed ratio. Two common
prediction equations were used to predict
expected daily water intake. The predicted
intakes were higher (P<0.05) than observed
intakes.
Introduction
There has been very little research on beef cattle
water intake. Water has been traditionally
considered an inexpensive, readily available, and
renewable natural resource. However, as human
populations continue to soar, and major cities
continue to grow at nearly exponential rates, this
may not always be the case in the future.
Water intake is poorly understood in beef cattle
and differences that may exist between animals
of different genders and breed types has not
been clearly defined. A number of prediction
equations have been developed to help estimate
expected water intake in dairy and beef cattle.
However, the equations were developed under
varying circumstances and may or may not be
accurate for all classes of cattle.
The purpose of this study was to 1) measure
water intake in growing beef cattle, 2) detect
intake differences in water intake between
animals of different genders and breed types,
and 3) examine performance factors that affect
or are affected by water intake. Additionally this
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2009 Florida Beef Report
Brainbridge, Ga), corn gluten feed (18.0%), and
calcium carbonate (1%). The total CP was
17.3%, NEm was 0.16 Mcal/lb, NEg was 0.11
Mcal/lb, and Na was 0.12%. Water was
available ad libitum. Following a two week
adjustment period all cattle were weighed
weekly (n=13).
Ambient temperature was
recorded by the Florida Automated Weather
Network (FAWN) from the substation in
Marianna.
study tested the suitability of two prediction
equations, the Murphy equation (Murphy et al.,
1983) and the Hicks equation (Hicks et al.,
1988), to predict water intake in growing Florida
beef cattle.
Procedures
The study was conducted at the University of
Florida’s North Florida Research and Education
Center (NFREC) at Marianna in northwest
Florida. Growing beef steers (n=61), heifers
(n=74), and bull calves (n=11) were housed at
the NFREC Feed Efficiency barn for the
duration of the study. This barn at the NFREC,
Marianna, FL was designed for use with the
GrowSafeTM system (GrowSafe Ltd, Airdrie,
Alberta, Canada) and was used for this study.
Each animal was fitted with a RFID ear tag prior
to the beginning of the study. The pens in the
barn are equipped GrowSafeTM feed bunkers and
water troughs. Adjustable head gates allow only
one animal to feed or drink at a time. When an
animal inserts its head into the bunker or trough
its RFID tag is automatically read by
GrowSafeTM hardware. This system allows the
measurement of feed and water intake of
animals individually while being reared in
groups. The barn is open-sided and the pens
have concrete floors; sawdust bedding was used.
Data were analyzed using SAS version 9.0 (SAS
Inst, Inc., Cary, NC). The experimental unit was
individual animal, rather than pen, as
GrowSafeTM allows for individual measurements
to be recorded. Variables measured included
water intake, feed intake, water intake adjusted
for metabolic BW , feed intake adjusted for
metabolic BW, average daily gain (ADG), and
gain-to-feed ratio ( G:F). For the determination
of the effect of breed/breed composite, only
those groups with eight or more animals were
used.
Using actual body weight, feed intake, feed
composition, and weather data gathered during
this study, the expected daily water intake for
each animal was calculated using the Murphy et
al. (1983) and the Hicks et al. equations (1988).
These predicted intakes were then compared to
actual intakes and means were separated
statistically using a Student’s T Test.
Twelve different breeds and breed composites
were represented. Sire breeds used included
Angus (AN), Brangus (BN), and Charolais
(CH). Maternal breeds included BN, AN,
Hereford x Angus (HFAN), Romosinuano (RS),
Romosinuano x Angus (RA), Simmental (SM),
Brangus x Hereford (BH,) and Simmental x
Angus (SMAN). The resulting breeds and
composites were; ANBN (n=13), BN (n=58),
BNAN (n=13), BNHFAN (n=1), BNRS (n=18),
BNRA (n=1), CHAN (n=8), CHBH (n=1),
CHBN (n=15), CHRS (n=15), CHSM (n=1) and
CHSMAN (n=2). Average starting weight was
607 ±147 lb/ head. Cattle were randomly
assigned to pens of 15 to 20 head per pen.
Results
Mean water intake (WI) was 7.92 ± 2.26 gal/d
per head. When adjusted for metabolic BW,
cattle drank an average of 0.007 ± 0.002 gal/lb
of metabolic BW. The cattle gained an average
of 3.10 ± 2.27 lb/d per head and G: F was 0.14 ±
0.11 lb weight gain per lb of feed intake. The
average daily temperature was 59 ± 14 F and
remained within the thermal neutral zone (40 to
70 F) for the duration of the study.
When adjusted for metabolic BW, CHAN cattle
drank significantly more than all other breed
composites (P< 0.05; Table 1). The BNAN
cattle followed and drank more water per unit of
metabolic BW than all other breeds except
CHAN. The CHBN, BN, BNAN, CHRS and
BNRS were similar (P>0.05) in adjusted water
Cattle were allowed ad libitum access to a total
mixed ration feed. The diet was composed of
whole dry corn (38.0 %), soybean hulls (18.1%),
cottonseed hulls (13.6%), Beefmaker 60
supplement (11.6%; Flint River Mills,
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intake, drinking less than CHAN and BNAN
cattle (P<0.05). The BNRS cattle had the lowest
intakes per unit of metabolic BW, but the
average intake was not statistically different
from average intakes of the CHBN, BN, BNAN,
And CHRS groups. These results indicated that
cattle with tropically adopted cattle breeding
tended to consume less water than British and
Continental influenced cattle at the same
metabolic BW.
there was no relationship between per unit of
metabolic BW and G: F (P=0.7556; Table 3).
When run through a regression equation, ADG
was found to be a function of water intake
adjusted for metabolic BW (R2=0.005) with a
weak linear relationship. Average daily gain was
slightly more linear in relation to gross water
intake (R2=0.009). The strongest linear
relationships existed between feed intake and
water intake (R2 = 0.13), feed intake adjusted for
metabolic BW and water intake adjusted for
metabolic BW (R2=0.084), feed intake adjusted
for metabolic BW and gross water intake (R2 =
0.055) and feed intake and water intake adjusted
for metabolic BW (R2 = 0.014).
Bulls, heifers, and steers were all similar in both
gross and adjusted water intake (P>0.05; Table
2). Only a small number of bulls; however, were
used in the comparison.
Gross WI was related to ADG (P<0.0007) but
was not correlated with G:F (P=0.5677; Table3).
Cattle who consumed greater quantities of water
gained more weight overall (P<0.05), but were
not necessarily more or less efficient at doing so
than cattle who consumed less water. When
adjusted for metabolic BW, water intake was
positively correlated with feed intake
(P<0.0001), feed intake per unit of MBW
(P<0.0001), and ADG (P=0.0164). Once again
The mean observed water intake for all cattle
was 7.9 gal/d per head. The Hicks equation
(Hicks et al., 1988) predicted that they would
consume 10.1gal/d per head while the Murphy
equation (Murphy et al., 1983) predicted an
intake of 13.2 gal/d per head. Thus, these two
equations overestimated intake (P<0.05) by a
factor of 2.2 and 5.3 gal/d per head, respectively.
Literature Cited
Hicks, R.B., F.N. Owens, D. Gill, J.J. Martin, and C.A. Strasia. 1988. Okla. Anim. Sci. Rpt. No. 125.
Animal Sciences Dept, Oklahoma State University, Stillwater. pp 208.
Murphy, M.R., C.L. Davis, and G.C. McCoy. 1983. J. Dairy Sci. 66:35-43.
Acknowledgements
The assistance of Meghan Brennan, Don Jones, Harvey Standland, and Charles Nowell is greatly appreciated.
1
Megan Brew, former Graduate Student, Bob Myer, Professor, Jeff Carter, former Assistant Professor, and Gary
Hansen, former Assistant Professor, UF-IFAS, North Florida Research and Education Center, Marianna, FL; and
Matt Hersom, Assistant Professor, UF-IFAS, Department of Animal Sciences, Gainesville, FL.
3
Table 1. Water intake by breed
Breed
Gross water intake gal/d 1,2
Water intake per MBW 1,3
a
Charolais x Angus
11.2
0.011 a
b
Angus x Brangus
8.5
0.008 b
Brangus
8.1 b
0.006 c
b
Charolais x Brangus
7.8
0.007c, b
b
Brangus x Angus
7.6
0.006 c
c
Brangus x Romosinuano
6.4
0.006 c
c
Charolais x Romosinuano
6.3
0.006 c
1
Within a column, means without a common superscript letter differ (p<0.05).
2
Gross water intake is expressed in gallons per head per day.
3
Water intake per MBW (metabolic body weight) is expressed as gallons per pound of metabolic BW per
day per head.
Table 2. Water intake by gender
Gender
Gross water intake, gal/d 1,2
Water intake per MBW 1,3
Bull
7.4a
0.006a
a
Steer
8.1
0.007a
a
Heifer
7.8
0.007a
1
Within a column, means without a common superscript letter differ (p<0.05).
2
Gross water intake is expressed in gallons per head per day.
3
Water intake per MBW (metabolic body weight) is expressed as gallons per pound of metabolic BW per
day per head.
Table 3. Significance (P Values) of correlations between water intake, feed intake, weight gain and feed
efficiencya.
FI
FMB
WI
WMB
ADG
G:F
FI
<0.0001
<0.0001
<0.0001
<0.0001
0.0271
FMB
<0.0001
<0.0001
<0.0001
<0.0001
0.0004
WI
<0.0001
<0.0001
<0.0001
0.0007
0.5677
WMB
<0.0001
<0.0001
<0.0001
0.0164
0.7556
ADG
<0.0001
<0.0001
0.0007
0.0164
<0.0001
G:F
<0.0001
<0.0004
0.5677
0.7556
<0.0001
a
P values less than or equal to 0.05 are significant
FI = feed intake per day
FMB = Feed intake adjusted for metabolic body weight
WMB = water intake adjusted for metabolic body weight
ADG = average daily gain
G:F = gain-to-feed ratio or feed efficiency
4
Characterization of the Acute-Phase Protein Response Following Vaccination
and Weaning in Beef Steers
R. F. Cooke1
D. B. Araujo
J. D. Arthington
Vaccination with One Shot® stimulates a greater inflammatory response in Brahman x British steers
compared to UltraBac® 7 and saline control, particularly during the 5 d following vaccination.
Summary
The objectives of this study were to assess the
acute-phase protein response of beef steers
following vaccination with two different
vaccines, and to determine if this response is
additive to weaning. Forty-eight Brahman x
Angus steers (average age = 7 mo) were
randomly assigned to one of six treatments in a
2 x 3 factorial arrangement, including: weaning
vs. non-weaning, and vaccination with One
Shot® (2 mL), UltraBac® 7 (5 mL), or saline
control (5 mL). Blood samples were collected on
d 0, 1, 3, 5, 7, 10, 14, and 21, relative to
weaning and vaccination, for determination of
plasma concentrations of inflammatory acutephase proteins. During the course of the study,
free-choice hay and a grain-based supplement
(up to 10 lbs/steer daily) were offered to weaned
steers, while non-weaned steers remained with
their dams. Weaned steers had greater (P<0.05)
ceruloplasmin concentrations on d 3, and
greater haptoglobin concentrations on d 3
(P<0.01) and 5 (P<0.05) compared to nonweaned steers. Across weaning treatment, steers
administered One Shot® had greater (P<0.01)
fibrinogen concentrations on d 1, 3, and 5,
greater (P<0.01) acid soluble protein
concentrations on d 3, and greater (P<0.01)
haptoglobin concentrations on d 1 and 3
compared to steers receiving UltraBac® 7 or
saline control. Within weaned steers, those
receiving One Shot® had greater (P<0.05) mean
ceruloplasmin concentrations compared to
steers receiving UltraBac® 7 or saline control.
Data from this study imply that steers vaccinated
with One Shot® experience a greater
inflammatory response compared to steers
vaccinated with UltraBac® 7 and saline control,
and this response mainly occurs during the 5 d
following vaccination. Further, additive effects
of vaccination on weaning were only detected
for plasma ceruloplasmin concentrations.
Introduction
The acute-phase response is a component of the
innate body defense, and results in the
production of a large and varied group of hepatic
proteins (Carroll and Forsberg, 2007). These
proteins, denominated acute-phase proteins
(APP), are synthesized by the liver parenchymal
cells and released into the bloodstream in
response to several stressors, including local
inflammation, bacterial infections, endotoxin
injections, and physical injuries (Carroll and
Forsberg, 2007). Recent research from our group
indicated
that
elevated
blood
APP
concentrations are detrimental to growth rates of
cattle (Qiu et al., 2007); therefore, recognition of
management procedures that stimulate the acutephase response, and search for alternatives to
alleviate APP synthesis will benefit beef cattle
productivity.
In Florida’s cow-calf operations, stressful
practices such as weaning, vaccination, and
transportation of calves may occur together or in
a short period of time. Weaning and shipping
have been shown to stimulate the acute-phase
response in cattle (Arthington et al., 2003;
5
Arthington et al., 2005), whereas administration
of vaccines containing adjuvants also increase
blood concentrations of APP (Stokka et al.,
1994). Therefore, calves vaccinated at weaning
could exhibit additive effects on circulating APP
concentrations. In addition, this increase may
vary depending on the individual vaccine
composition.
Diagnostics BCA kit following plasma acidsoluble protein extraction as described by
Nakajima et al., 1982).
Data were analyzed using the PROC MIXED
procedure of SAS (SAS Inst., Inc., Cary, NC).
The model statement contained the effects of
weaning treatment, vaccination treatment, d (for
plasma APP analysis only), and the consequent
interactions. Steer within weaning treatment by
vaccination treatment was classified as the
random variable. Steer was considered the
experimental unit. Results are reported as LS
means, and were separated using PDIFF.
Pearson correlation coefficients among all APP
and ADG were generated using the CORR
procedure of SAS. Significance was set at
P≤0.05, and tendencies were determined if
P>0.05 and ≤0.10. Only significant interactions
are reported.
The objectives of this study was to assess the
APP response of beef calves following
vaccination with two different types of vaccines,
and to determine if this response is additive to
the weaning process.
Materials and Methods
Forty-eight Brahman x British crossbred steers
were randomly allocated to one of the two
weaning treatments: 1) Weaned calves or 2)
Non-weaned calves, where weaned calves were
separated from dams at the beginning of the
study (d 0), whereas non-weaned calves
remained with respective dams throughout the
entire experimental period, with free access to
bahiagrass (Paspalum notatum) pasture. Steers
were further randomly allocated within weaning
treatments, in a 2 x 3 factorial arrangement, to
one of the three vaccination treatments: A) One
Shot® (2 mL subcutaneous; Pfizer Animal
Health, New York, NY), B) UltraBac® 7 (5 mL
subcutaneous; Pfizer Animal Health), or C)
Saline control (5 ml subcutaneous). Vaccination
treatments were also applied on d 0 of the study.
For weaned steers, stargrass (Cynodon
nlemfuensis) hay was offered in amounts to
ensure ad libitum intake together with grainbased supplement (72% TDN, 14% CP; DM
basis), which was offered up to 10 lbs/steer
daily.
Full bodyweight (BW) was obtained on d 0 and
at the end of the study (d 21) for average daily
gain (ADG) calculation. Blood samples were
collected via jugular venipuncture into sodiumheparinized
Vacutainer
tubes
(Beckton
Dickinson, Franklin Lakes, NJ) on d 0, 1, 3, 5, 7,
10, 14, and 21 for plasma collection and
determination of fibrinogen (Sigma diagnostic
procedure n° 880; Sigma Diagnostics, St. Louis,
MO), ceruloplasmin (Demetriou et al., 1974),
haptoglobin (Makimura and Suzuki, 1982), and
acid soluble protein concentrations (ASP; Sigma
Results
Weaned steers had greater (P<0.01) ADG
compared to non-weaned steers (0.94 vs. 0.51
lbs/d, respectively; SEM=0.09). This effect can
be attributed to the fact that weaned steers had
access to free-choice hay and grain-based
supplements, whereas the major source of
nutrients for non-weaned steers was low-quality
pasture and milk. No effects on ADG were
observed among vaccination treatments (Table
1). The present study, however, was mainly
designed to evaluate the APP response of both
vaccination and weaning treatments, and not
growth rates. Steer ADG was calculated using
full BW instead of shrunk BW to avoid the
addition of another stress source. This,
combined to the short duration of the
experimental period (21 d), is not adequate to
have an acceptable assessment of animal growth.
A weaning treatment x day interaction was
detected (P<0.01) for ceruloplasmin (Figure 1)
and haptoglobin (Figure 2). Weaned steers had
greater (P<0.05) ceruloplasmin concentrations
on d 3, and greater haptoglobin concentrations d
3 (P<0.01) and d 5 (P<0.05) compared to nonweaned steers. These results support previous
data from our research group indicating that the
weaning process stimulates the acute-phase
response in beef calves (Arthington et al., 2003;
Arthington et al., 2005).
6
Vaccination treatment x day interactions were
detected (P<0.01), independently of weaning
treatment, for fibrinogen, ASP, and haptoglobin
analysis. Fibrinogen concentrations were greater
(P<0.01; Figure 3) for One Shot® vaccinatedsteers compared to saline control and Ultra Bac®
7 vaccinated-steers on d 1, 3, and 5, and tended
to be greater for One Shot® vaccinated-steers
compared to saline control and Ultra Bac® 7
vaccinated-steers on d 7 (P=0.06 and 0.10,
respectively). Concentrations of ASP were
greater (P<0.01; Figure 4) for One Shot®
vaccinated-steers compared to saline control and
Ultra Bac® 7 vaccinated-steers on d 3, and
tended to be greater for One Shot® vaccinatedsteers compared to saline control and Ultra Bac®
7 vaccinated-steers on d 5 (P=0.07 and 0.10,
respectively). Haptoglobin concentrations were
greater (P<0.01; Figure 5) for One Shot®
vaccinated-steers compared to saline control and
Ultra Bac® 7 vaccinated-steers on d 1 and 3, but
greater for Ultra Bac® 7 vaccinated-steers
compared to saline control (P<0.01) and One
Shot® vaccinated-steers (P<0.05) on d 5. Within
weaned steers only, mean ceruloplasmin
concentrations during the study were greater
(P<0.05) for One Shot® vaccinated-steers
compared to saline control or Ultra Bac® 7
vaccinated-steers (Table 1).
In conclusion, data from this study imply that
steers vaccinated with One Shot® have greater
inflammatory response compared to cohorts
vaccinated with UltraBac® 7 or saline control,
and this response is mainly observed during the
following 5 d after vaccination. Additive effects
between vaccination and weaning were only
observed
for
plasma
ceruloplasmin
concentrations. Furthermore, significant positive
correlations were observed among all APP;
however none was negatively correlated herein
with steer ADG.
Correlation coefficients among concentrations of
ceruloplasmin, fibrinogen, ASP, haptoglobin (all
pooled across d) and ADG were determined
among all steers (n=46) with Pearson correlation
coefficient (Table 2). Significant positive
correlations were observed among all APP.
However, only haptoglobin was significantly
correlated with ADG (P<0.05; Table 2), and this
correlation was positive. Haptoglobin has been
negatively associated with ruminal pH (Gozho et
al., 2005; Gozho et al., 2006). Since ADG is
associated positively with supplement intake
(Vizcarra et al., 1998; Lapierre et al., 2000), and
supplement intake is negatively correlated with
rumen pH (Gozho et al., 2005; Gozho et al.,
2006), it can be speculated that steers with
greater haptoglobin concentrations were those
that consumed more grain-based supplement,
and consequently had lower ruminal pH but
greater ADG.
7
Literature Cited
Arthington et al. 2003. J. Anim. Sci. 83:933-939.
Arthington et al. 2005. J. Anim. Sci. 81:1136-1141.
Carroll and Fosberg, 2007. Vet. Clin. Food. Anim. 23:105-149.
Demetriou et al. 1974. Clinical Chemistry 857-864
Gozho et al. 2005. J. Dairy Sci. 88:1399-1403
Gozho et al. 2006. J. Dairy Sci. 89:4404-4413
Lapierre et al. 2000. J. Anim Sci. 78:1084-1099
Makimura and Suzuki. 1982. Jpn. J. Vet. Sci. 44:15-21.
Stokka et al. 1994. J. Am. Vet. Med. Assoc. 204:415-419.
Vizcarra et al. 1998. J. Anim Sci. 76:927-936
Qiu et al., 2007. J. Anim. Sci. 85:2367-2374
1
R. F. Cooke, Former Graduate Student; D. B. Araujo, Graduate Student; J. D. Arrthington, UFIFAS Range Cattle Research and Education Center, Ona, FL
8
Table 1. Average daily gain (ADG) and plasma ceruloplasmin concentrations of weaned or nonweaned steers, vaccinated with One Shot®, UltraBac® 7 or saline control a.b.
ADG (lbs/d) c
Ceruloplasmin (mg/100mL)
One Shot®
1.03 ± 0.15 a
28.37 ± 1.34 a
UltraBac® 7
0.94 ± 0.15 a
24.18 ± 1.35 b
Saline control
0.85 ± 0.17 a
24.49 ± 1.45 b
One Shot®
0.65 ± 0.17 a
25.80 ± 1.43 a
UltraBac® 7
0.43 ± 0.16 a
26.01 ± 1.44 a
Saline control
0.43 ± 0.15 a
24.13 ± 1.35 a
Weaned steers
Non-weaned steers
a
Values reported as mean ± standard error
Within weaning treatment and variable, values with different letters differ (P < 0.05)
c
Calculated using initial (d 0) and final (d 21) full BW
b
Table 2. Correlations between plasma measurements and ADG of steers a.
Item
Ceruloplasmin Acid soluble protein
Haptoglobin
Acid soluble protein
Fibrinogen
0.27
0.07
Haptoglobin
Fibrinogen
ADG b
a
b
0.45
0.41
< 0.01
< 0.01
0.33
0.35
0.52
< 0.05
< 0.05
< 0.01
- 0.05
0.11
0.31
-0.03
0.72
0.46
< 0.05
0.81
Upper row = correlation coefficients. Lower row = P–values.
Calculated using initial (d 0) and final (d 21) full BW
9
Figure 1. Plasma ceruloplasmin concentrations of weaned and non-weaned steers. A weaning
treatment x day interaction was detected (P < 0.01). Daily comparison between weaning treatments; *
P < 0.05.
40.0
Ceruloplasmin, mg/100mL
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
Weaned
0
1
3
5
7
10
Day of Study
14
Non-weaned
21
Figure 2. Plasma haptoglobin concentrations of weaned or non-weaned steers. A weaning treatment
x day interaction was detected (P < 0.01). Daily comparison between weaning treatments; * P < 0.05,
and ** P < 0.01.
Haptoglobin, Abs @ 450 nm (x 100)
0.06
0.05
0.04
0.03
0.02
0.01
0.00
Weaned
0
1
3
Non-weaned
5
7
10
14
21
Day of Study
10
Figure 3. Plasma fibrinogen concentrations of steers vaccinated with One Shot®, UltraBac® 7, or saline
control. A vaccination treatment x day interaction was detected (P < 0.01). Daily comparison among
vaccination treatments: ** One Shot® vs. Ultra Bac® 7 and saline control (P < 0.01); † One Shot® vs.
Ultra Bac® 7 and saline control (P = 0.06 and 0.10, respectively).
500.0
Fibrinogen, mg/100mL
450.0
400.0
350.0
300.0
250.0
200.0
150.0
100.0
50.0
One Shot®
0
1
3
5
7
UltraBac® 7
10
Saline Control
14
21
Day of Study
11
Figure 4. Plasma acid soluble protein concentrations of steers vaccinated with One Shot®, UltraBac®
7, or saline control. A vaccination treatment x day interaction was detected (P < 0.01). Daily
comparison among vaccination treatments: ** One Shot® vs. Ultra Bac® 7 and saline control (P < 0.01);
† One Shot® vs. Ultra Bac® 7 and saline control (P = 0.07 and 0.10, respectively).
Acid Soluble Protein, mg/100mL
180.0
160.0
140.0
120.0
100.0
80.0
60.0
40.0
20.0
One Shot®
0.0
0
1
3
5
7
UltraBac® 7
10
Saline Control
14
21
Day of Study
Figure 5. Plasma haptoglobin concentrations of steers vaccinated with One Shot®, UltraBac® 7, or saline
control. A vaccination treatment x day interaction was detected (P < 0.01). Daily comparison among
vaccination treatments: ** One Shot® vs. Ultra Bac® 7 and saline control (P < 0.01); * Ultra Bac® 7 vs.
One Shot® and saline control (P < 0.05 and 0.01, respectively).
Haptoglobin, Abs @ 450 nm (x 100)
0.10
0.09
One Shot®
0.08
Saline Control
UltraBac® 7
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
1
3
5
7
10
14
21
Day of Study
12
Effects of Acclimation to Handling on Performance, Reproductive, and
Physiological Responses of Brahman-crossbred Heifers
R. F. Cooke1
B. R. Austin
J. V. Yelich
J. D. Arthington
Acclimation to human handling after weaning hastened the onset of puberty in Brahman-crossbred
heifers.
Summary
The objective of this experiment was to evaluate
the effects of acclimation to human handling on
growth, plasma concentrations of cortisol, and
puberty attainment of Brahman-crossbred
heifers. Over two consecutive yr, 37 Braford and
43 Brahman × Angus heifers were assigned
randomly to receive or not the acclimation
treatment within 30 d after weaning. The
acclimation process consisted of bringing
heifers to the cowpens three times weekly during
four consecutive wk, where heifers were exposed
to common handling practices and returned to
pastures within 2 h. Heifers were maintained in
bahiagrass (Paspalum notatum) pastures and
received a blend of soybean hulls and cottonseed
meal at a daily rate of 6.0 lbs of DM per heifer
during the experiment (d 0 to 130). Blood
samples were collected prior to and at the end of
the acclimation process for determination of
cortisol concentrations. Puberty status was
assessed monthly during the experiment.
Acclimated heifers had decreased (P<0.05)
average daily gain (ADG) compared to control
heifers (1.1 vs. 1.3 lbs/d, respectively).
Attainment of puberty, however, was hastened
(P<0.01) for acclimated heifers. Further,
acclimated heifers had reduced cortisol
concentrations compared to control heifers after
the acclimation period (3.8 vs. 5.1 μg/dL,
respectively). Results from this experiment
indicated that although acclimation decreased
body weight gain, it enhanced the attainment of
puberty in Brahman-crossbred heifers.
Introduction
Age at puberty is influenced by breed type, and
heifers containing Brahman breeding typically
reach puberty after 15 mo of age (Plasse et al.,
1968; Rodrigues et al., 2002). In addition to this
genetic effect, Brahman-crossbred heifers are
often described as temperamental, and this trait
is expected to further negatively influence their
reproductive function (Plasse et al., 1970). Cattle
with
excitable
temperament
experience
stimulated
secretion
and
circulating
concentrations of ACTH and cortisol (Curley et
al., 2008). These hormones directly impair the
mechanisms
responsible
for
puberty
establishment of heifers, such as synthesis and
release of gonadotropins (Li and Wagner, 1983;
Dobson et al., 2000). However, acclimation of
beef females to handling has been reported to
alleviate these negative physiological effects of
temperament on reproduction (Echternkamp,
1984). Based on these previous observations, we
hypothesized that Brahman-crossbred heifers
exposed to handling acclimation procedures
after weaning would experience improved
temperament, alleviated adrenal steroidogenesis,
and enhanced reproductive performance. The
objectives of the present experiment were to
compare growth, temperament, plasma
13
measurements,
puberty
attainment
and
pregnancy rates of Brahman × Angus and
Braford heifers exposed or not to acclimation
procedures.
Diagnostic Products Inc., Los Angeles, CA). All
samples were analyzed in duplicates.
Heifer temperament scores were also obtained
on d 40, following blood collection and
ultrasonography exam, to evaluate treatment
effects. Heifer temperament was assessed by pen
score, chute score, and chute exit velocity. Chute
score was assessed by a single technician based
on a 5-point scale, where 1 = calm, no
movement, and 5 = violent and continuous
struggling. For pen score assessment, heifers
exited the chute and entered a pen containing a
single technician, and were assigned a score on a
5-point scale, where 1 = unalarmed and
unexcited, and 5 = very excited and aggressive
toward the technician in a manner that requires
evasive action to avoid contact between the
technician and heifer. Exit velocity was assessed
by determining the speed of the heifer exiting
the squeeze chute by measuring rate of travel
over a 1.5-m distance with an infrared sensor
(FarmTek Inc., North Wylie, TX). Further,
within each assessment d (d 10 and 40), heifers
were divided in quintiles according to their exit
velocity, and assigned a score from 1 to 5 (exit
score; 1 = slowest heifers; 5 = fastest heifers).
Individual temperament scores were calculated
by averaging heifer chute score, pen score, and
exit score.
Over two consecutive yr, 37 Braford (37.5%
Brahman + 62.5% Hereford) and 43 Brahman ×
Angus (approximately 25% Brahman) heifers
were initially evaluated for puberty status via
trans-rectal ultrasonography (d 0 and 10) and for
temperament by measurements of chute score,
pen score, and exit velocity (d 10) within 30 d
after weaning. On d 10, heifers were stratified
by puberty status, temperament and body weight
(BW), and randomly assigned to control or
acclimation treatment. Heifers were maintained
in bahiagrass (Paspalum notatum) pastures and
received a blend of soybean hulls and cottonseed
meal at a daily rate of 6.0 lbs of DM per heifer
throughout the experimental period (d 0 to 130).
The acclimation process (d 11 to 39) consisted
of bringing heifers to the cowpens three times
weekly, where heifers were exposed to common
handling practices and returned to pastures
within two h. Heifer shrunk (after 16 h of feed
and water restriction) BW was collected on d 1
and 192 for calculation of heifer ADG during
the experiment. Heifer puberty status, evaluated
via plasma progesterone concentrations and
trans-rectal ultrasonography, was assessed on d
40 and 50, d 80 and 90, and d 120 and 130.
Heifers were considered pubertal once a corpus
luteum and plasma progesterone concentrations
greater than 1.5 ng/mL (Cooke et al., 2007) were
concurrently detected in one or both evaluations
performed on a 10-d interval.
Growth, temperament, and physiological data
were analyzed using the MIXED procedure of
SAS (SAS Inst., Inc., Cary, NC). The model
statement contained the effects of treatment,
breed, time variables (when appropriate), and
consequent interactions. Data were analyzed
using heifer(breed × treatment × yr) as random
variable. Results are reported as LS means and
were separated using LSD. Puberty data were
analyzed with the GLM and LOGISTIC
procedure of SAS. The model statement
contained the effects of treatment, breed, time of
estimated puberty establishment, year, and the
appropriate interactions. Significance was set at
P≤0.05 and tendencies were determined if P>
0.05 and ≤0.10.
Blood samples collected prior to (d 10) and at
the end of the acclimation process (d 40) were
also
evaluated
for
plasma
cortisol
concentrations. Blood samples were collected
via jugular venipuncture into commercial blood
collection tubes (Vacutainer, 10 mL; Becton
Dickinson, Franklin Lakes, NJ) containing
sodium heparin, placed on ice immediately, and
centrifuged at 2,400 × g for 30 min for plasma
collection. Plasma was frozen at -20°C on the
same d of collection. Concentrations of
progesterone and cortisol were determined using
Coat-A-Count solid phase 125I RIA kits (DPC
Results
Acclimated heifers had reduced (P<0.01) ADG
compared with control heifers (1.1 vs. 1.3 lbs/d
14
respectively; SEM=0.04). Given that both
treatment groups were provided similar pastures
and supplements during the experiment,
treatment effects on ADG can be attributed to
the additional exercise that acclimated heifers
were exposed to during the acclimation period.
During each acclimation event, heifers had to
walk nearly 1.3 miles in addition to the activity
inside the handling facility, whereas control
heifers remained on their pasture. A treatment
effect was also detected (P<0.05) for puberty
attainment. Although age at puberty in cattle is
highly determined by BW and growth rate
(Schillo et al., 1992), heifers exposed to
acclimation procedures reached puberty sooner
than control heifers despite their reduced ADG
(Figure 1).
mechanisms by which acclimation procedures
hastened puberty attainment regardless of
decreased ADG remain unclear. Based on our
hypothesis, it can be speculated that reduced
cortisol concentrations in acclimated heifers
facilitated the initiation of the physiological
events required for puberty attainment,
particularly the first ovulatory LH surge (Smith
and Dobson, 2002). Although concentrations of
cortisol were only evaluated when heifers were
handled and restrained for blood collection, one
can speculate that acclimated heifers also had
reduced cortisol concentrations compared to
control heifers on a daily basis given that heifers
from both groups were often exposed to brief
human interaction, particularly because of
feeding and traffic of personnel/vehicles within
the research station. Still, additional research
should be conducted to further address these
assumptions.
Acclimated heifers had reduced (P<0.01)
cortisol concentrations compared with control
heifers after the acclimation period (3.8 vs. 5.1
μg/dL; SEM=0.17; Figure 2). Supporting our
results, previous research indicated that
acclimation of cattle to handling procedures was
an alternative to prevent elevated concentrations
of cortisol in response to handling stress
(Crookshank et al., 1979; Andrade et al., 2001;
Curley et al., 2006). However, no treatment
effects were detected for temperament scores
(Table 1), although acclimated heifers had
reduced chute score (P<0.01) compared with
control heifers after the acclimation period
(Table 1). Further, all measurements of
temperament were positively correlated to each
other, and also to cortisol concentrations
(P<0.01; Table 2). The positive correlations
detected among measurements of temperament
and cortisol concentrations reported herein were
also described by others (Stahringer et al. 1990;
Fell et a., 1999; Curley et al., 2006), suggesting
that these three measurements of cattle behavior
during handling can be used as indicators of
temperament and also denote the amount of
stress that the animal is experiencing (Thun et
al., 1998; Sapolsky et al., 2000).
In conclusion, results from this experiment
indicate that acclimation of Brahman-crossbred
heifers to handling procedures and human
interaction reduced ADG because of the
additional exercise that heifers were exposed to,
but alleviated adrenal steroidogenesis and
hastened onset of puberty. Therefore,
acclimation of Brahman × Angus and Braford
replacement heifers to human handling after
weaning may be an alternative to enhance their
reproductive development, and increase the
efficiency of heifer development programs in
cow-calf operations containing Brahmaninfluenced cattle.
Supporting our main hypothesis and rationale,
acclimated heifers in the present experiment had
reduced cortisol concentrations, decreased chute
score, and hastened onset of puberty compared
with non-acclimated cohorts. Nevertheless, the
15
Literature Cited
Andrade et al. 2001. Appl. Anim. Behav. Sci. 71:175-181.
Cooke et al. 2007. J. Anim. Sci. 85:2564-2574.
Crookshank et al. 1979. J. Anim. Sci. 48:430-435.
Curley et al. 2006. J. Anim. Sci. 84:3100-3103.
Curley et al. 2008. Horm. Behav. 53:20-27.
Dobson et al. J. Reprod. Fertil. 120:405-410.
Echternkamp. 1984. Theriogenology 22:305-311.
Fell et al. 1999. Aust. J. Exp. Agric. 39:795-802.
Li and Wagner. 1983. Biol. Reprod 29:25-37.
Plasse et al. 1968. J. Anim. Sci. 27:94-100.
Rodrigues et al. 2002. Biol. Reprod. 66:603-609.
Sapolsky et al. 2000. Endocr. Rev. 21:55-89.
Schillo et al. 1992. J. Anim. Sci. 70:3994-4005.
Smith and Dobson. 2002. Domest. Anim. Endocrinol. 23:75-85.
Stahringer et al. 1990. Theriogenology 34:393-406.
Thun et al. 1998. Reprod. Dom. Anim. 33:255-260.
1
R. F. Cooke, Former Graduate Student; B. R. Austin, Graduate Student; J. V. Yelich, Associate
Professor, UF- IFAS Animal Sciences , Gainesville, FL ; J. D. Arthington, UF-IFAS Range Cattle
Research and Education Center, Ona, FL
16
Table 1. Temperament measurements, obtained after the acclimation period, of heifers exposed or not
(control) to handling acclimation procedures. 1
Item
Acclimated
1
Control
SEM
P-Value
Temperament score
2.46
2.48
0.096
0.93
Chute score
1.37
1.84
0.091
< 0.01
Pen score
2.85
2.72
0.137
0.51
Exit velocity, m/s
2.91
2.74
0.148
0.43
Values reported are covariately adjusted means.
Table 2. Pearson correlation coefficients among measurements of temperament and plasma cortisol
concentrations of heifers. 1
Item
1
Cortisol
Chute score
Chute score
0.44
< 0.01
Exit velocity
0.55
< 0.01
0.46
< 0.01
Pen score
0.48
< 0.01
0.40
< 0.01
Exit velocity
0.69
< 0.01
Upper row = correlation coefficients. Lower row = P–values.
17
100
Acclimated
90
Control
Pubertal heifer, %
80
70
60
50
40
30
20
10
0
d 0 and 10
d 40 and 50
d 80 and 90
d 120 and 130
Figure 1. Puberty attainment of heifers exposed or not (control) to handling acclimation
procedures (d 11 to 39). Heifers were considered pubertal once a corpus luteum and plasma P4
concentrations greater than 1.5 ng/mL were concurrently detected in one or both evaluations
performed on a 10-d interval. A treatment effect was detected (P=0.02; SEM=6.5).
7
Acclimated
Control
Plasma cortisol, μg/dL
6
5
4
3
2
1
0
Pre-acclimation (d 10)
Post-acclimation (d 40)
Figure 2. Plasma cortisol concentrations of heifers exposed or not (control) to handling acclimation
procedures (d 11 to 39). Samples collected on d 10 served as covariate, therefore results reported for d 40
are covariately adjusted least square means. Acclimated heifers had reduced (P<0.01; SEM=0.17)
concentrations of cortisol compared to control heifers on d 40.
18
Effects of Excitable Temperament and its Physiological Consequences on
Reproductive Performance of Brahman-crossbred Cows
R. F. Cooke1
D. B. Araujo
G. C. Lamb
J. D. Arthington
Measurements and physiologic responses associated with cow temperament, acute phase response, and
energy status influence the probability of Brahman-crossbred cows to become pregnant during the
breeding season
Summary
The objective of this experiment was to evaluate
the effects of cow temperament, acute phase
response, and energy status on the probability of
Brahman-crossbred cows to become pregnant
during the breeding season. Over two
consecutive yr, 160 Braford and 235 Brahman ×
British cows were exposed to mature Angus
bulls during a 90-d breeding season. Prior to
the beginning of breeding, cows were evaluated
for body condition score (BCS) and
temperament, while blood samples were
obtained for determination of plasma
concentrations of insulin-like growth factor I
(IGF-I),
cortisol,
ceruloplasmin
and
haptoglobin. During year 1, probability of
pregnancy during the breeding season increased
linearly (P<0.05) as temperament score and
concentrations of ceruloplasmin, haptoglobin,
and cortisol (Braford cows only) decreased,
whereas BCS and IGF-I concentrations affected
the probability of pregnancy quadratically
(P<0.05). During year 2, probability of
pregnancy increased linearly (P<0.05) as
concentrations
of
ceruloplasmin
and
haptoglobin
decreased,
whereas
BCS,
temperament score, and concentrations of
cortisol and IGF - I affected the probability of
pregnancy quadratically (P<0.05).
These
results suggest that measurements and
physiologic
responses
associated
with
temperament, health, and energy status
influence the probability of cows to become
pregnant during the breeding season.
Introduction
The major objective of cow-calf production
systems is to produce one calf per cow annually.
Ovulation of a competent oocyte determines the
length of the postpartum interval and also the
fertility of beef cows during the breeding season
(Short et al., 1990). Follicle size and LH
pulsatility are major factors responsible for a
successful ovulation (Roche, 2006); therefore,
alternatives to stimulate GnRH delivery to the
pituitary, and anticipate/enhance the ovulatory
LH surge are options to maximize reproductive
performance of beef cows (Day, 1994).
Several factors are known to influence GnRH
and gonadotropin synthesis in cattle. Cattle with
excitable temperament often experience
stimulated
secretion
and
circulating
concentrations of ACTH and cortisol (Curley et
al., 2008), and these hormones directly impair
19
synthesis and release of GnRH and
gonadotropins (Li and Wagner, 1983; Dobson et
al., 2000). Animals under inflammatory
processes, such as the acute phase response, may
also
experience
impaired
GnRH
and
gonadotropin production (Peter et al., 1989;
Battaglia et al., 2000; Williams et al., 2001).
Additionally, energy intake and level of body
reserves
directly
modulate
circulating
concentrations of IGF-I (Wettemann et al.,
2003), which in turn may enhance GnRH and
gonadotropin synthesis, and also potentiate the
effects of gonadotropins in the ovary (Spicer and
Stewart, 1996; Wettemann et al., 2003).
Therefore, the objective of this study was to
determine the probability of cows to become
pregnant during the breeding season, according
to BCS, temperament score, and concentrations
of IGF-I, cortisol, and acute phase proteins
assessed at the beginning of breeding.
slowest cows; 5 = fastest cows). Individual
temperament scores were calculated by
averaging cow chute score, pen score, and exit
score.
Blood samples were collected via jugular
venipuncture into commercial blood collection
tubes (Vacutainer, 10 mL; Becton Dickinson,
Franklin Lakes, NJ) containing sodium heparin,
placed on ice immediately, and centrifuged at
2,400 × g for 30 min for plasma collection.
Plasma was frozen at -20°C on the same day of
collection. Concentrations of cortisol were
determined using a Coat-A-Count solid phase
125
I RIA kit (DPC Diagnostic Products Inc., Los
Angeles, CA). A double antibody RIA was used
to determine concentrations and IGF-I (Badinga
et al., 1991; Cooke et al., 2007). Concentrations
of ceruloplasmin were determined according to
procedures described by Demetriou et al. (1974).
Concentrations of haptoglobin were determined
by measuring haptoglobin/hemoglobin complex
by the estimation of differences in peroxidase
activity (Makimura and Suzuki, 1982).
Over two consecutive years, 160 Braford and
235 Brahman × British cows were evaluated for
BCS (emaciated = 1, obese = 9; Wagner et al.,
1988) and plasma concentrations of IGF-I,
cortisol, ceruloplasmin, and haptoglobin at the
beginning of the breeding season. Cows were
exposed to mature Angus bulls for 90-d,
whereas bull to cow ratio was, respectively, 1:20
for both breed types.
The probability of cows to become pregnant
during the breeding season was determined with
the GLM and LOGISTIC procedures of SAS.
The GLM procedure was utilized to determine if
each individual measurement influenced
pregnancy rates linearly, quadratically, and/or
cubically. If multiple continuous order effects
were significant, the effect with the greatest Fvalue was selected. The LOGISTIC procedure
was utilized to determine the intercept and
slope(s) values according to maximum
likelihood estimates from the significant effect
selected, and the probability of pregnancy was
determined according to the equation:
Probability = (e logistic equation) / (1 + e logistic equation).
Logistic curves were constructed according to
the minimum and maximum values detected for
each individual measurement.
Cow temperament was assessed by pen score,
chute score, and exit velocity. Chute score was
assessed by a single technician based on a 5point scale, where 1 = calm, no movement, and
5 = violent and continuous struggling. For pen
score assessment, cows exited the chute and
entered a pen containing a single technician, and
were assigned a score on a 5-point scale, where
1 = unalarmed and unexcited, and 5 = very
excited and aggressive toward the technician in a
manner that requires evasive action to avoid
contact between the technician and cow. Exit
velocity was assessed by determining the speed
of the cow exiting the squeeze chute by
measuring rate of travel over a 1.5-m distance
with an infrared sensor (FarmTek Inc., North
Wylie, TX). Further, cows were divided in
quintiles according to their exit velocity, and
assigned a score from 1 to 5 (exit score; 1 =
Results
The probability of cows to become pregnant,
according to measurements obtained at the
beginning of the breeding season, was evaluated
within each year because mean days post-partum
across breeds at the onset of breeding differed
(P<0.01) from yr 1 to yr 2 (88 vs. 34 d,
20
respectively;
SEM=1.5).
Plasma
IGF-I
concentrations and cow BCS affected
quadratically (P<0.01) the probability of
pregnancy during both yr (Figure 1). These
results indicate that reduced or excessive energy
status is detrimental to reproductive performance
of cattle, as reported by others (Armstrong et al.,
2001; Bilby et al., 2006; Cooke et al., 2008b).
Cow temperament score and plasma cortisol
concentrations affected the probability of
pregnancy linearly (P=0.03) during yr 1, and
quadratically (P<0.01) during yr 2 (Figure 2).
These results suggest that excitable temperament
and consequent elevated cortisol concentrations
(Curley et al., 2008) are detrimental to
reproductive function of cows. Concurring with
our findings, Plasse et al. (1970) reported that
excitable temperament influences negatively the
reproductive performance of beef females.
Additionally, as observed in yr 2, reduced
cortisol concentrations and temperament score
during the early postpartum period may denote
health disorders that negatively affect cattle
reproduction, such as lethargy, lameness
(Sprecher et al., 1997), and immunosuppresion
(Goff, 2006). Plasma concentrations of
ceruloplasmin and haptoglobin affected the
probability of pregnancy linearly during yr 1
(P<0.01 and =0.04, respectively) and yr 2
(P=0.01; Figure 3), suggesting and supporting
previous data indicating that the acute phase
response is detrimental to reproductive function
of livestock (Peter et al., 1989; Battaglia et al.,
2000; Williams et al., 2001).
In conclusion, results from this study indicate
that measurements and physiologic responses
associated with cow temperament, acute phase
response, and energy status influenced the
probability of cows to become pregnant during
the breeding season. Therefore, management
strategies that improve cow disposition, enhance
their immune status, and maintain the cowherd
at adequate levels of nutrition are required for
optimal reproductive performance of Brahmancrossbred cows, and consequent productivity of
cow-calf operations containing these types of
cattle.
21
Literature Cited
Armstrong et al. 2001. Biol. Reprod. 64:1624-1632.
Badinga et al. 1991. J. Anim. Sci. 69:1925-1934.
Battaglia et al. 2000. Biol. Reprod. 62:45-53.
Bilby et al. 2006. J. Dairy Sci. 89:3360-3374.
Cooke and Arthington. 2008. Prof. Anim. Sci. 24:264-268.
Cooke et al. 2007. J. Anim. Sci. 85:2564-2574.
Curley et al. 2008. Horm. Behav. 53:20-27.
Day. 2004. Anim. Reprod. Sci. 82-83:487-494.
Demetriou et al. 1974. Clinical Chemistry 857-864
Dobson et al. J. Reprod. Fertil. 120:405-410.
Goff. 2006. J. Dairy Sci. 89:1292-1301.
Li and Wagner. 1983. Biol. Reprod 29:25-37.
Makimura and Suzuki. 1982. Jpn. J. Vet. Sci. 44:15-21.
Peter el al. 1989. Am. J. Vet. Res. 50:368-373.
Spicer and Stewart. 1996. Biol. Reprod. 54:255-263.
Sprecher et al. 1997. Theriogenology 47:1179-1187.
Wagner et al. 1988. J. Anim. Sci. 66:603-612.
Wettemann et al. 2003. J. Anim. Sci. 81(E. Suppl. 2):E48-E59.
Williams et al. 2001. Endocrinology 142:1915-1922.
1
R. F. Cooke, Former Graduate Student; D. B. Araujo, Graduate Student; G. C. Lamb,
Associate Professor, UF- IFAS North Florida Research and Education Center, Marianna FL;
J. D. Arthington, UF-IFAS Range Cattle Research and Education Center, Ona, FL
22
100
Year 1
90
Year 2
80
70
60
50
40
Probability of pregnancy, %
30
20
10
0
1
2
3
4
5
6
7
8
9
BCS
100
Year 1
90
Year 2
80
70
60
50
40
30
20
10
0
0
50
100
150
200
250
300
350
Plasma IGF-I, ng/mL
Figure 1. Effects of BCS (emaciated = 1, obese = 9; Wagner et al., 1988) and plasma IGF-I concentrations,
assessed at the beginning of the breeding season, on the probability of Brahman-crossbred cows
to become pregnant. A quadratic effect was detected during yr 1 and 2 for BCS (P<0.01) and
plasma IGF-I (P=0.02 and <0.01, respectively).
23
100
90
80
70
60
50
40
30
20
10
Year 1
Year 2
0
1
2
3
Temperament Score
4
5
100
90
80
70
60
50
40
30
20
10
Year 1
0
0
Figure 2
1
2
Year 2
3
4
5
6
Plasma cortisol, μg/dL
7
8
9
Effects of temperament score and plasma cortisol concentrations, assessed at the beginning of the
breeding season, on the probability of Brahman × British and Braford cows to become pregnant.
For temperament score, a linear effect (P=0.03) and a quadratic effect (P<0.01) were detected for
both breeds during yr 1 and 2, respectively. For plasma cortisol, a linear effect was detected
(P=0.04) for Braford cows during yr 1, whereas a quadratic effect was detected (P=0.02) for both
breeds during yr 2.
24
100
90
80
70
60
50
40
30
20
10
Year 1
0
0
5
Year 2
10
15
20
25
30
35
40
Plasma ceruloplasmin, mg/dL
100
90
80
70
60
50
40
30
20
10
Year 1
0
0
1
2
Year 2
3
4
5
6
7
8
9
10
Plasma haptoglobin, 450 nm × 100
Figure 3. Effects of plasma ceruloplasmin and haptoglobin concentrations, assessed at the beginning of
the breeding season, on the probability of Brahman-crossbred cows to become pregnant. A
linear effect was detected during yr 1 and 2 for plasma ceruloplasmin (P<0.01 and =0.01,
respectively) and haptoglobin (P=0.04 and =0.01, respectively).
25
26
Effects of Day of Cycle at Initiation of a Select Synch/CIDR + Timed-artificial
Insemination Protocol in Suckled Angus and Brangus Cows
Regina Esterman1
Brad Austin
Steaven Woodall
Erin McKinniss
Joel Yelich
In anestrous cows, synchronized pregnancy rates were similar for Angus and Brangus cows, as well as for
cows that ovulated to GnRH on d 0 and cows that failed to ovulate to GnRH on d 0. In estrous cycling
cows, day of the estrous cycle at initiation of the Select Synch/CIDR + timed-artificial insemination
protocol affected ovulation rate and ovulatory follicle sizes on d 0, estrous response, conception rate,
timed-AI pregnancy rate, and synchronized pregnancy rate. Synchronized pregnancy rates were similar
for both anestrous and estrous cycling cows, regardless of whether they ovulated to GnRH on d 0 or failed
to ovulate to GnRH on d 0 of the synchronization protocol.
Summary
Postpartum Angus (n=37) and Brangus (n=37)
cows were used to evaluate cycling status and
day of estrous cycle (DOC) effects at initiation
of a Select Synch/CIDR + timed artificial
insemination (AI) protocol on ovulation rate,
follicle development, and pregnancy rates. The
experiment was conducted in two phases (phase
1=anestrous, phase 2=estrous cycling).
Anestrous cows were selected to have either
ovulated to GnRH on d 0 (n=6 Angus, n=6
Brangus) or not ovulated to GnRH on d 0 (n=6
Angus, n=6 Brangus). Estrous cycling cows
were pre-synchronized to be d 2, 6, 10, 14, and
18 DOC on d 0 of synchronization (Angus=5;
Brangus=5 per DOC group). In phase 1,
anestrous cows had similar (P>0.05) ovulatory
follicle sizes for Angus (12.7 ± 0.7 mm) and
Brangus (13.7 ± 0.7 mm). Total ovulation rate
following PGF2α was similar (P>0.05) for Angus
(83.3%) and Brangus (91.7%), as well as for
cows that ovulated to GnRH (91.7%) and failed
to ovulate to GnRH (83.8%). Estrous response
(ER) tended (P=0.17) to be greater for Brangus
(41.7%) compared to Angus (16.7%). Cows
that ovulated to GnRH also tended (P=0.17) to
have a greater ER compared to cows that failed
to ovulated to GnRH (16.7%). Conception rate
(CR) was similar (P>0.05) for Angus (50.0%)
and Brangus (40.0%) cows, but cows that
ovulated to GnRH (60.0%) tended (P=0.09) to
have a greater CR compared to cows that failed
to ovulate to GnRH (0.0%).
Timed-AI
pregnancy rate (TAIPR) was similar (P>0.05)
for Angus (30.0%) and Brangus (42.9%), but
TAIPR tended (P=0.11) to be greater for cows
that failed to ovulate to GnRH (50.0%)
compared to cows that ovulated to GnRH
(14.3%). Synchronized pregnancy rates were
similar (P>0.05) for both Angus (33.3%) and
Brangus (41.7%), as well as for cows that
ovulated to GnRH (33.3%) and failed to ovulate
to GnRH (41.7%). In phase 2, breed had no
effect (P>0.05) on ovulation rate to GnRH
(Angus=56%; Brangus=52%) and ovulatory
follicle size on d 0 (Angus=13.9 ± 1.8 mm;
Brangus=14.1 ± 2.4 mm). Day of cycle affected
(P<0.05) ovulation rate to GnRH and ovulatory
follicle size. Estrous response was greater
(P<0.05) for Brangus (48%) compared to Angus
(28%), but CR, TAIPR, and SPR were similar
(P>0.05) for Angus and Brangus. However,
DOC affected (P<0.05) ER, CR, TAIPR, and
27
SPR for DOC groups.
Materials & Methods
The experiment was conducted from March to
June of 2007 at the University of Florida,
Department of Animal Sciences, Santa Fe Beef
Research Unit in two phases (phase 1=anestrous,
phase 2=estrous cycling). Postpartum lactating
Angus (n=37) and Brangus (n=37) cows were
utilized. For the first phase of the experiment,
on d -12 and -2 blood samples were collected for
the evaluation of progesterone concentrations to
determine estrous cycling status. A cow was
deemed to have estrous cycles (cycling) if either
sample had progesterone concentrations ≥ 1
ng/mL, and anestrous (noncycling) if
progesterone concentrations were < 1 ng/mL at
both samples. Only cows determined to be
anestrous were utilized for the first phase of the
experiment. Day 0 was designated as the start of
the synchronization protocol. At the start of
phase 1 synchronization, Angus and Brangus
cows, respectively, were 2 yr of age, body
weight 1,038 ± 31 lb and 1,025 ± 31 lb, body
condition score (1=emaciated, 9=obese) 5.0 ±
0.1 and 5.2 ± 0.1, and 72.0 ± 4.6 d and 61.5 ±
4.6 d. For phase 2, Angus and Brangus cows,
respectively, were 5.3 ± 2.4 y and 3.6 ± 1.1 y of
age, body weight 1,192 ± 95 lb and 1,188 ± 139
lb, body condition score 5.3 ± 0.4 and 5.4 ± 0.5,
and d postpartum 59.2 ± 2.4 d and 54.7 ± 11.1 d.
Introduction
Inclusion of GnRH at the start of a
synchronization protocol causes ovulation of
follicles greater than 10 mm in diameter. By
ovulating the largest follicle present, the cow
will begin a new wave of follicle growth. With
a new wave of follicle growth, follicle
development can be better synchronized within a
group of cows. By synchronizing both follicle
development and luteal lifespan (using PGF2α), a
more synchronous estrus can be achieved
following PGF2α administration.
Due to differences in a cow’s length of estrous
cycle and number of follicular waves, predicting
when GnRH will be most effective can be a
challenge. GnRH is effective once a dominant
follicle reaches 10 mm in diameter and
continues until the follicle either ovulates on its
own or becomes atretic and regresses in
preparation for the next follicular wave. Across
all stages of the estrous cycle, it is estimated that
60 to 70% of Bos taurus cows will ovulate to
GnRH. Cattle of Bos indicus breeding are
known to frequently have a greater number of
follicular waves and more variability to their
length of estrous cycle. With greater numbers of
follicular waves, the windows of opportunity for
GnRH to be effective are shortened. However,
recent research from our lab would suggest that
ovulation rates in cattle of Bos indicus breeding
are at or slightly below that of Bos taurus cattle.
In phase 1 (anestrous cows), on d 0 of the
experiment, all cows received GnRH (100 µg;
i.m., Cystorelin®, Merial) and a new CIDR (1.38
g; Eazi-Breed™ CIDR®, Pfizer Animal Health).
On d 2, ovulation status to GnRH was evaluated
and cows that ovulated to GnRH (n=6) and cows
that failed to ovulate to GnRH (n=6) within each
breed group were selected to continue on the
experiment. On d 7, the CIDR was removed
and cows received PGF2α (25 mg, i.m.,
Lutalyse , Pfizer Animal Health).
Therefore, the objectives of this experiment
were to: 1) evaluate follicle development
following ovulation or no ovulation to GnRH in
anestrous Angus and Brangus cows, 2) evaluate
luteolysis, estrous characteristics, and pregnancy
rates following ovulation or no ovulation to
GnRH in anestrous Angus and Brangus cows, 3)
determine ovulation rates to GnRH in cycling
Angus and Brangus cows known to be on d 2, 6,
10, 14, & 18 of their estrous cycles, and 4)
evaluate luteolysis, estrous characteristics, and
pregnancy rates
following the
Select
Synch/CIDR + timed-AI protocol in cycling
Angus and Brangus cows known to be on d 2, 6,
10, 14, & 18 of their estrous cycles.
In phase 2 (estrous cycling cows), cows were
pre-synchronized using a 7 d CIDR with PGF2α
on d 7 to be on either d 2, 6, 10, 14, or 18 of
their estrous cycle (DOC) at the start of
synchronization. Following PGF2α in the presynchronization, estrous was detected visually
with the aid of estrous detection patches
(Estrotect™, Rockway, Inc.) and the day each
cow displayed estrus was determined to be d 0
28
of that cow’s estrous cycle. Pre-synchronization
groups were staggered over several weeks prior
to the synchronization in order for all cows to
began the synchronization on the same day. On
d 0 of synchronization, all cows received GnRH
and a new CIDR. On d 7, the CIDR was
removed and cows received PGF2α.
PGF2α to the onset of estrus was similar
(P>0.05) for Angus and Brangus cows.
However, cows that ovulated to GnRH on d 0
had a greater (P<0.05) interval from PGF2α to
the onset of estrus compared to cows that did not
ovulate to GnRH on d 0. Duration of estrus
tended (P=0.06) to be longer for Angus cows
compared to Brangus cows, but duration of
estrus was similar (P>0.05) whether cows
ovulated or did not ovulate to GnRH on d 0.
The number of mounts received during estrus
was similar (P>0.05) for Angus and Brangus
cows. Cows that ovulated to GnRH on d 0
tended (P=0.13) to receive more mounts (34.2)
compared to cows that did not ovulate to GnRH
(21.5).
Following PGF2α in both phases, estrus was
monitored using electronic heat detection
monitors (HeatWatch®, DDx) for 3 d. Cows
were inseminated by a single AI technician 8 to
12 h after declared in estrus by the HeatWatch®
system. Cows were inseminated using frozenthawed semen from multiple sires.
The GENMOD procedure of SAS (SAS Inst.
Inc.) was used for the statistical analysis of
categorical data. The effect of breed, DOC, and
their interaction were evaluated for ovulation
rate to GnRH, estrous response, conception rate,
timed-AI pregnancy rate, and synchronized
pregnancy rate, while cow age, DPP, BCS, and
interval from PGF2α to the onset of estrus were
included as covariates. The effect of ovulation
or no ovulation to GnRH, breed, and interaction
were evaluated for estrous response, conception
rate, timed-AI pregnancy rate, and synchronized
pregnancy rate, while cow age, DPP, BCS, and
included as covariates. When covariates were
significant (P < 0.05) they were treated as
independent variables. The effect of breed,
DOC, and the interaction on follicle diameters
were analyzed using GLM procedure of SAS.
Conception rate was similar (P>0.05) for Angus
and Brangus cows (Table 2).
Cows that
ovulated to GnRH on d 0 tended (P=0.09) to
have a greater conception rate (60.0%; 3/5)
compared to cows that did not ovulate to GnRH
on d 0 (0%; 2/2). Timed-AI pregnancy rate was
similar (P>0.05) for Angus and Brangus cows
(Table 2), but cows that ovulated to GnRH on d
0 tended (P=0.11) to have a lower timed-AI
pregnancy rate compared to cows that did not
ovulate to GnRH on d 0 (14.3%; 1/7 and 50.0%;
5/5, respectively). Synchronized pregnancy rate
was similar (P>0.05) for Angus and Brangus
cows, as well as for cows that ovulated or failed
to ovulate to GnRH on d 0 (Table 2).
In phase 2 (estrous cycling), ovulation rate to
GnRH on d 0 was similar (P>0.05) between
Angus and Brangus cows (Table 3). Day of the
estrous cycle effected (P<0.05) ovulation rate to
GnRH. No cows (0/10) that were on d 2 of their
estrous cycle at the start of synchronization
ovulated to GnRH on d 0. Cows on d 6, 10, 14,
& 18 of their estrous cycles had ovulation rates
to GnRH of 100, 30, 70 and 70%, respectively.
Size of the follicle ovulated to GnRH on d 0 was
similar (P>0.05) for Angus (13.9 mm) and
Brangus (14.1 mm) cows. However, cows on
DOC 6 and 14 ovulated smaller (P<0.05)
follicles to GnRH compared to cows on DOC 10
or 18.
Results
In phase 1 (anestrous cows), ovulatory follicle
size in response to GnRH on d 0 for cows that
ovulated was 13.2 ± 0.5 mm. Ovulatory follicle
size was similar (P>0.05) for Angus (12.7 ± 0.7
mm) and Brangus (13.7 ± 0.7 mm) cows.
Luteal regression was 100% for both Angus and
Brangus and cows, as well as 100% for cows
that ovulated to GnRH on d 0. Estrous response
tended (P=0.17) to be greater for Brangus
compared to Angus (Table 1). Estrous response
also tended (P=0.17) to be greater for cows that
ovulated to GnRH on d 0 compared to cows that
did not ovulate to GnRH on d 0. Interval from
29
Luteal regression following PGF2α was similar
(P>0.05) for both Angus (92.0%; 23/25) and
Brangus (92.0%; 23/25) cows. Luteolysis was
100% for cows DOC 10, 14, and 18, but was
lower (P<0.05) for cows DOC 2 and 6 (both
80%). Ovulation rate following PGF2α was
similar (P>0.05) for Angus (88.0%; 22/25) and
Brangus (92.0%; 23/25).
Ovulation rate
following PGF2α tended (P=0.12) to be different
between DOC groups with ovulation rates of
70.0, 90.0, 90.0, 100.0, and 100.0% for cows
DOC 2, 6, 10, 14, and 18, respectively.
Ovulatory follicle size following PGF2α was
similar (P>0.05) for Angus (15.0 ± 0.6 mm) and
Brangus (15.3 ± 0.6 mm) cows. However, DOC
tended (P=0.06) to effect ovulatory follicle size
following PGF2α.
Ovulatory follicle size
following PGF2α was similar (P>0.05) for DOC
2 (13.6 ± 0.9 mm), 6 (14.1 ± 0.8 mm), 10 (15.0
± 0.8 mm), and 14 (15.4 ± 0.8 mm). Ovulatory
follicle size was greater (P<0.05) for DOC 18
(16.9 ± 0.8 mm) compared to DOC 2 and 4, but
was similar (P>0.05) to DOC 10 and 14.
Cows that ovulated to GnRH on d 0 (47.4%;
9/19) had similar (P>0.05) conception rates
compared to cows that failed to ovulate to
GnRH on d 0 (57.1%; 4/7). Conception rates
were similar (P>0.05) for Angus compared to
Brangus cows (Table 5). Conception rate was
effected (P<0.05) by DOC.
Timed-AI
pregnancy rates were similar (P>0.05) for
Angus and Brangus cows. Timed-AI pregnancy
rate was effected (P<0.05) by DOC. Cows that
failed to ovulate to GnRH on d 0 (42.9%; 12/28)
tended (P=0.09) to have a greater timed-AI
pregnancy rate compared to cows that ovulated
to GnRH on d 0 (20.0; 4/20). Synchronized
pregnancy rate was similar (P>0.05) for Angus
and Brangus cows. Cows 2, 6, and 18 DOC had
similar (P>0.05) synchronized pregnancy rates,
but were lower (P<0.05) compared to cows 10
and 14 DOC. However, cows 10, 14, and 18
DOC were similar (P>0.05) to each other.
Synchronized pregnancy rates were similar
(P>0.05) for cows that ovulated to GnRH on d 0
(33.3%; 13/39) and cows that failed to ovulate to
GnRH on d 0 (45.7%; 16/35).
Estrous response was greater (P<0.05) for cows
that ovulated to GnRH on d 0 (48.7%; 19/39)
compared to cows that failed to ovulate to
GnRH on d 0 (20.0%; 7/35). Estrous response
was greater (P=0.05) for Brangus compared to
Angus cows (Table 4). Estrous response was
different (P<0.05) for DOC groups.
Interval
from PGF2α to the onset of estrus was similar
(P>0.05) for Angus and Brangus cows, but
tended (P=0.11) to be different for DOC groups.
Duration of estrus tended (P=0.12) to be greater
for Brangus cows (11 h 15 m) compared to
Angus cows (8 h 46 m). Duration of estrus was
similar (P>0.05) for DOC groups. Brangus
cows received a greater (P<0.05) number of
mounts during estrus (53.9) compared to Angus
cows (20.3). Number of mounts received during
estrus was similar (P>0.05) for DOC groups.
In conclusion, DOC when a Select Synch/CIDR
+ timed-AI synchronization protocol is initiated
affected ovulation rates to GnRH and ovulatory
follicle size to GnRH on d 0. Cows that
ovulated to GnRH on d 0 and cows that failed to
ovulate to GnRH on d 0 had similar
synchronized pregnancy rates. Estrous response,
conception rate, timed-AI pregnancy rate, and
synchronized pregnancy rate were influenced by
DOC.
1
Regina Esterman, Graduate Student; Brad Austin, Graduate Student; Steaven Woodall, Former
Graduate Student; Erin McKinniss, Graduate Student; Joel Yelich; Associate Professor, UF-IFA,
Department of Animal Sciences, Gainesville, FL
30
Table 1. Effect of breed and ovulation status to GnRH on d 0 (OVGnRH) on estrous characteristics
following PGF2 in anestrous Angus and Brangus cows synchronized with a Select Synch + CIDR and
timed-AI synchronization protocol.a
Variable
n
Estrous
response, %b
Angus
12
16.7 (12)
49 h 5 m ± 3 h
44 m
16 h 20 m ± 3 h
53 m
32 ± 7.6
12
41.7 (12)
49 h 6 m ± 2 h
21 m
5 h 21 m ± 2 h
27 m
30 ± 4.8
OV to
GnRH
12
41.7 (12)
51 h 16 m ± 1 h
30 m
6h8m±3h
1m
34.2 ± 3.8
No OV to
GnRH
12
16.7 (12)
43 h 40 m ± 2 h
22 m
14 h 20 m ± 4 h
46 m
21.5 ± 6.0
Breed
P = 0.17
P > 0.05
P = 0.06
P > 0.05
OVGnRH
P = 0.17
P = 0.04
P > 0.05
P = 0.13
Breed
P > 0.05
P > 0.05
P = 0.04
P > 0.05
Brangus
Interval from
PGF2 to onset of
estrus (hr, min)c
Duration of
estrus (hr, min)d
Total mounts
during estruse
P values
OVGnRH
a
All cows received GnRH at initiation of the 7 d CIDR treatment, with PGF 2 administered at the time of
CIDR removal. Estrus was detected for 3 d, and cows that exhibited estrus were AI approximately 8 to 12
h later. Cows which had not displayed estrus were timed-AI at 76 to 80 h and given GnRH.
b
Percentage of cows displaying estrus 3 d after PGF2 of the total treated.
c
Time from PGF2 administration to the first mount of estrus, as determined by HeatWatch®.
d
Time from the first mount of estrus to the last mount of estrus, as determined by HeatWatch®
e
Total mounting events which occurred during estrus, as determined by HeatWatch®.
.
31
Table 2. Effect of breed and ovulation status to GnRH on d 0 (OVGnRH) on estrous response,
conception, timed-AI pregnancy, and synchronized pregnancy rates following PGF2 in anestrous
Angus and Brangus cows synchronized with a Select Synch + CIDR and timed-AI synchronization
protocol.a
Variable
n
Estrous
response, %b
Angus
12
16.7 (12)
50.0 (12)
30.0 (10)
33.3 (12)
OV to
GnRH
6
16.7 (6)
100.0 (1)
0.0 (5)
16.7 (6)
No OV to
GnRH
6
16.7 (6)
0.0 (1)
60.0 (5)
50.0 (6)
12
41.7 (12)
40.0 (5)
42.9 (7)
41.7 (12)
OV to
GnRH
6
66.7 (6)
50.0 (4)
50.0 (2)
50.0 (6)
No OV to
GnRH
6
16.7 (6)
0.0 (1)
40.0 (5)
33.3 (6)
Breed
P = 0.17
P > 0.05
P > 0.05
P > 0.05
OVGnRH
P = 0.17
P = 0.09
P = 0.11
P > 0.05
Breed
P > 0.05
P > 0.05
P = 0.06
P = 0.19
Brangus
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Synchronized
pregnancy rate,
%e
P values
OVGnRH
a
All cows received GnRH at initiation of the 7 d CIDR treatment, with PGF2 administered at the time of
CIDR removal. Estrus was detected for 3 d, and cows that exhibited estrus were AI approximately 8 to 12
h later. Cows which had not displayed estrus were timed-AI at 76 to 80 h and given GnRH.
b
Percentage of cows displaying estrus 3 d after PGF2 of total treated.
c
Percentage of cows pregnant to AI of the total that exhibited estrus and were AI.
d
Percentage of cows pregnant to timed-AI of the total that were timed-AI.
e
Percentage of cows pregnant during the synchronized breeding of the total treated.
32
Table 3. Effect of breed and day of estrous cycle on ovulation rates to GnRH and ovulatory follicle
size (LS mean SE) in estrous cycling Angus and Brangus cows synchronized with a Select Synch +
CIDR and timed-AI synchronization protocol.a
Variable
n
Follicles ovulating to GnRH,
%b
Angus
25
56.0 (25)
13.9 ± 0.6 (11 to 17)
25
52.0 (25)
14.1 ± 0.6 (10 to 18)
d2
10
0.0 (10)
.
d6
10
100.0 (10)
13.2 ± 0.6 (11 to 17)d
d 10
10
30.0 (10)
15.7 ± 1.0 (14 to 17)e
d 14
10
70.0 (10)
12.7 ± 0.7 (10 to 14)d
d 18
10
70.0 (10)
15.6 ± 0.7 (14 to 18)e
P > 0.05
P > 0.05
Brangus
Ovulatory follicle size, mm,
(range)c
P values
Breed
DOC
P < 0.05
P < 0.05
CIDR removal. Estrus was detected for 3 d, and cows that exhibited estrus were AI approximately 8 to
12 h later. Cows which had not displayed estrus were timed-AI at 76 to 80 h and given GnRH.
a
b
Percentage of cows that ovulated to GnRH on d 11 divided by the total treated.
c
Size of the largest follicle on d 0 that ovulated by 48 h later.
d,e
Means without a common superscript within a column differ (P<0.05).
33
Table 4. Effect of breed and day of estrous cycle on estrous characteristics as determined by
HeatWatch of estrous cycling Angus and Brangus cows synchronized with a Select Synch + CIDR
and timed-AI synchronization protocol.a With the exception of estrous response estrous characteristics
are presented as LS means SE.a
Variable
n
Estrous
response, %b
Angus
25
28.0 (25)
49 h 2 m ±
3h 39 m
8 h 46 m ±
1 h 14 m
20.3 ± 10.4
25
48.0 (25)
54 h 26 m ±
2h 47 m
11 h 15 m ±
57 m
53.9 ± 8.0
d2
10
0.0 (10)f
.
.
.
d6
10
10.0 (10)g
64 h 24 m ±
8h 48 mf,g
12 h 15 m ±
3 h 28 m
30.0 ± 31.8
d 10
10
30.0 (10)g,h
62 h 20 m ±
5h 5 mf
11 h 38 m ±
2h0m
61.7 ± 18.3
d 14
10
60.0 (10)h,i
50 h 2 m ±
3h 35 mf,g
11 h 18 m ±
1 h 25 m
49.7 ± 13.0
d 18
10
90.0 (10)i
49 h 26 m ±
2h 56 mg
9h3m±
1h9m
30.7 ± 10.6
Breed
P = 0.05
P > 0.05
P = 0.12
P < 0.05
DOC
P < 0.01
P = 0.11
P > 0.05
P > 0.05
Brangus
Interval from
PGF2 to onset of
estrus (hr, min)c
Duration of
estrus (hr,
min)d
Total mounts
during estruse
P values
a
CIDR removal. Estrus was detected for 3 d, and cows that exhibited estrus were AI approximately 8 to 12 h
later. Cows which had not displayed estrus were timed-AI at 76 to 80 h and given GnRH.
b
Percentage of cows displaying estrus 3 d after PGF2 of the total treated.
c
Time from PGF2 administration to the first mount of estrus, as determined by HeatWatch®.
d
Time from the first mount of estrus to the last mount of estrus, as determined by HeatWatch®.
e
Total mounting events which occurred during estrus, as determined by HeatWatch®.
f,g,h,i
34
Table 5. Effect of breed and day of estrous cycle on estrous response and pregnancy rates in cycling
Angus and Brangus cows synchronized with a Select Synch + CIDR and timed-AI synchronization
protocol.a
Variable
n
Estrous response,
%b
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Synchronized
pregnancy rate,
%e
Angus
25
28.0 (25)
57.1 (7)
38.9 (18)
44.0 (25)
Brangus
25
48.0 (25)
50.0 (12)
23.1 (13)
36.0 (25)
d2
10
0.0 (10)
0.0 (0)
10.0 (10)
10.0 (10)f
d6
10
10.0 (10)
100.0 (1)
11.1 (9)
20.0 (10)f
d 10
10
30.0 (10)
100.0 (3)
57.1 (7)
70.0 (10)g
d 14
10
60.0 (10)
33.3 (6)
100.0 (4)
60.0 (10)g
d 18
10
90.0 (10)
44.4 (9)
0.0 (1)
40.0 (10)f,g
P = 0.14
P > 0.05
P > 0.05
P > 0.05
P values
Breed
DOC
P < 0.05
P < 0.05
P < 0.05
P < 0.05
CIDR removal. Estrus was detected for 3 d, and cows that exhibited estrus were AI approximately 8 to
12 h later. Cows which had not displayed estrus were timed-AI at 76 to 80 h and given GnRH.
a
b
Percentage of cows displaying estrus 3 d after PGF2 of total treated.
c
d
e
f,g
35
36
Evaluation of a New or Once-used CIDR and Two Different Prostaglandin F2
Treatments to Synchronize Suckled Bos indicus  Bos taurus Cows
Regina D. Esterman1
Brad R. Austin
Steaven A. Woodall
Gary R. Hansen
Matt Hersom
Joel V. Yelich
Suckled Bos indicus  Bos taurus cows achieved similar pregnancy rates when synchronized with CIDR
inserts and two PGF2α types. Greater synchronized pregnancy rates were observed with a 3 d estrous
detection and clean-up timed artificial insemination compared to a 5 d estrous detection following
PGF2α. Days from calving had a strong influence on response to synchronization protocol.
Summary
Multiparous suckled Bos indicus  Bos taurus
cows were used in two experiments to evaluate
the Select Synch and Select Synch + timed
artificial insemination (TAI) synchronization
protocols combined with a controlled
intravaginal progesterone device (CIDR). Both
experiments were conducted as 2  2 factorial
designs with the main effects being CIDR type
(new vs once-used) and PGF2α type
(cloprostenol
sodium
vs
dinoprost
tromethamine).
Cows in both experiments
received GnRH and either a new CIDR or onceused CIDR on d 0, followed by CIDR removal
and either cloprostenol sodium or dinoprost
tromethamine on d 7. In Exp. 1, estrus was
detected for 5 d following PGF2α and cows were
AI 8 to 12 h after observed in estrus. In Exp. 2,
estrus was detected for 3 d following PGF2α and
cows were AI 8 to 12 h after observed in estrus.
Cows not exhibiting estrus by 72 h after PGF2α
were timed-AI between 76 to 80 h and received
GnRH. In Exp. 1, estrous response, conception,
and synchronized pregnancy rates were similar
(P>0.05) for both new and once-used CIDR, as
well as cloprostenol sodium and dinoprost
tromethamine. Interval from PGF2α to onset of
estrus influenced (P<0.05) conception rates.
Cows displaying estrus ≤ 84 h after PGF2α had
greater (P<0.05) conception rates compared to
cows exhibiting estrus ≥ 96 h after PGF2α. In
Exp. 2, estrous response, conception, timed-AI,
and synchronized pregnancy rates were similar
(P>0.05) for new and once-used CIDR, as well
as cloprostenol sodium and dinoprost
tromethamine. In both experiments, estrous
response, conception, and pregnancy rates
increased (P<0.05) as days from calving
increased. In summary, CIDR (new vs onceused) and PGF2α (cloprostenol sodium vs
dinoprost tromethamine) types resulted in
similar responses when used in the Select Synch
protocol and the response to synchronization
treatment increased as days from calving
increased in suckled Bos indicus  Bos taurus
cows.
Introduction
Estrous synchronization allows for more cows to
display estrus and ovulate over a period of
several days. This allows for either a reduction
of daily estrous detection over a 21 d estrous
cycle to 1 to 5 d, or elimination of estrous
detection and insemination of all cows at a predetermined time known as timed-AI.
A
frequently used and effective synchronization
protocol in Bos taurus cattle is administration of
GnRH followed 7 d later with PGF2α. However,
a common problem with the GnRH + PGF2α
37
synchronization protocols in suckled Bos indicus
 Bos taurus cows.
protocol is that some cattle express estrus
several days before PGF2α, which requires
additional estrous detection. This problem can
be eliminated with addition of a progestogen
between the GnRH and PGF2α treatments. An
added benefit of the progestogen is that it can
induce estrous cycles in some anestrous cows.
Limited research has been conducted using the
GnRH + PGF2α protocols in Bos indicus  Bos
taurus cattle either with or without a
progestogen and that research was met with
limited success. The reason(s) for the less than
acceptable results are unclear, but may be due to
a decreased synchronized estrous response,
which may be influenced by decreased luteolytic
actions of PGF2α.
Two experiments were conducted from January
to March during two successive years at the Bar
L Ranch in Marianna, FL. In Experiment 1,
multiparous, suckled Bos indicus  Bos taurus
cows (n = 284) were used. Mean ( SD) cow
age was 5.7 ± 1.9 yr, days postpartum (DPP)
was 58.0 ± 12.5 d, body weight (BW) was 1098
± 106 lbs, and body condition score was 5.2 ±
0.5 (BCS: 1 = emaciated, 9 = obese). The
percentage of Bos indicus breeding ranged from
approximately 10 to 38% with the remainder
being Bos taurus breeding. The experiment was
a 2  2 factorial design. At the start of the
experiment (d 0), cows were equally distributed
by DPP and cow age to one of two progesterone
treatments, which included a new CIDR (1.38 g;
Eazi-Breed™ CIDR®, Pfizer Animal Health)
and a once-used CIDR (new CIDR used once
and autoclaved before the second use). All cows
received GnRH (100 µg i.m.; Fertagyl®,
Intervet) at CIDR insertion and BCS were
recorded. On d 7, CIDR were removed and
cows within each CIDR treatment were equally
distributed by DPP, BCS, and cow age to
receive either cloprostenol sodium (cloprostenol;
500 µg i.m.; Estrumate®, Schering-Plough
Veterinary Corp.) or dinoprost tromethamine
(dinoprost; 25 mg i.m.; Prostamate®, Agrilabs).
All cows received an Estrotect™ estrous
detection patch (Estrotect™, Rockway, Inc.) at
CIDR removal to aid in estrous detection.
Several studies have reported similar responses
in Bos taurus cattle synchronized with
synchronization
systems
that
compared
cloprostenol sodium to dinoprost tromethamine,
but limited work has been done in Bos indicus 
Bos taurus cows.
The CIDR is an effective synchronization agent
that induces estrus in some anestrous cattle. A
new CIDR (1.9 g progesterone) maintains
circulating progesterone concentrations > 1
ng/mL for at least 15 d after insertion,
suggesting that a CIDR could be used for two
consecutive 7 d treatments and still suppress
estrus. Furthermore, autoclaving a once-used
CIDR brings more progesterone to the surface
making more available for absorption in the
vagina, as well as decreasing the possibility of
disease transmission. Re-use of the CIDR could
help producers decrease the cost of
synchronizing cattle, but it must be
accomplished without a reduction in AI
pregnancy rates. Evaluation of a once-used
CIDR has not been conducted in suckled Bos
indicus  Bos taurus cows.
Estrus was visually detected three times daily at
0700, 1200, and 1700 h for 5 d following PGF2α.
Estrus was defined as a cow standing to be
mounted by another cow and/or a half to full red
Estrotect™ patch. Cows were AI 8 to 12 h after
observed in estrus. Frozen-thawed semen from
a single sire of known fertility was used and
cows were inseminated by two AI technicians.
Seven d after the last cow was inseminated, bulls
were placed with cows.
Pregnancy was
diagnosed approximately 55 d after AI using a
real-time B-mode ultrasonography machine
Therefore, the objectives of these experiments
were to evaluate the effectiveness of a new
CIDR compared to a once-used CIDR and
cloprostenol sodium compared to dinoprost
tromethamine in two GnRH + PGF2α
38
(Aloka 500V, Corometrics Medical Systems)
with a 5.0 MHz transducer. Because there
was a 7-d period where cows were neither
inseminated nor exposed to bulls, differences in
fetal size were used to determine whether a
pregnancy resulted from the synchronized
breeding or clean-up bull.
(80.1%) treatment.
Days post partum effected (P<0.05) estrous
response, conception, and synchronized
pregnancy rates (Table 2). Cows that were long
(≥ 70 d) postpartum had a greater (P<0.05)
estrous response compared to cows that were
short (≤ 50 d) and medium (50 to 69 d)
postpartum, which were similar (P>0.05).
Conception rates were similar (P>0.05) for cows
that were medium and long postpartum, both of
which were greater (P<0.05) compared to short
postpartum cows. Synchronized pregnancy rates
were greater (P<0.05) for cows that were long
postpartum compared to short and medium
postpartum cows, which were different (P<0.05)
from each other. Thirty-day pregnancy rates
were greater (P<0.05) for cows that were
medium (79.1%) and long (87.8%) postpartum
compared to cows that were short (71.6%)
postpartum. Cows that were medium and short
postpartum had similar (P>0.05) thirty-day
pregnancy rates.
In Experiment 2, multiparous suckled Bos
indicus  Bos taurus cows (n = 259) were used.
Mean ( SD) cow age was 6.9 ± 1.9 yr, DPP
was 48.5 ± 12.8 d, and BCS was 5.1 ± 0.5. The
experiment was a 2  2 factorial design and
animals were assigned to the same
synchronization treatments as Experiment 1.
Estrus was detected for 72 h following PGF2α as
described in Experiment 1. Cows were AI 8 to
12 h after observed in estrus. All cows that had
not displayed estrus by 73 h after PGF2α were
timed-AI and received GnRH between 76 and 80
h after PGF2α. Cows were inseminated by a
single AI technician with frozen-thawed semen
from five sires that were pre-assigned to cows
before AI by the co-operating producer. Seven
days after the last cow was inseminated, bulls
were placed with cows and pregnancy was
diagnosed as described in Experiment 1. The
GENMOD procedure of SAS (SAS Inst. Inc.)
was used for the statistical analysis. The main
effects of CIDR and PGF2α treatments, and
CIDR  PGF2α were evaluated for estrous
response, conception, synchronized pregnancy,
and thirty-day pregnancy rates. Cow age, DPP,
BCS, and interval from PGF2α to the onset of
estrus were included as covariates. When
covariates were significant (P < 0.05), they were
treated as independent variables.
No cows were detected in estrus until 48 h after
PGF2 for any of the four treatments. The mean
interval from PGF2 to onset of estrus (64.4 ±
16.0 h) was not influenced (P>0.05) by main or
simple treatment effects. Interestingly, there
was an effect (P < 0.01) of interval from PGF2α
to onset of estrus on conception rate (Figure 1).
Cows which displayed estrus 48, 60, 72, and 84
h after PGF2α had similar (P>0.05) conception
rates, but cows which displayed estrus at 48, 60,
and 72 h had greater (P<0.05) conception rates
compared to cows that displayed estrus 96 h
after PGF2α. Cows that displayed estrus at 84 h
had similar (P>0.05) conception rates compared
to cows which displayed estrus at 96 h. Cow
age and BCS did not affect (P>0.05) estrous
response, conception rate, synchronized
pregnancy, or 30-d pregnancy rates when
included as covariates for main and simple
treatment effects.
Results
In Experiment 1, estrous response, conception
rate, and synchronized pregnancy rates were
similar (P>0.05) for main effects of CIDR and
PGF2α treatments, as well as the simple
treatment effects (Table 1).
Thirty-day
pregnancy rates were similar (P>0.05) for the
new (78.0%) compared to the once-used
(79.4%) CIDR treatment and for the
cloprostenol (77.3%) compared to the dinoprost
In Experiment 2, estrous response, conception
rate, timed-AI pregnancy, and synchronized
pregnancy rates were similar (P>0.05) for main
39
effects of CIDR and PGF2α treatments (Table
3). Thirty-day pregnancy rates were similar
(P>0.05) for the new (83.2%) compared to the
once-used (76.9%) CIDR treatment and for the
cloprostenol (76.7%) compared to the dinoprost
(83.3%) treatment.
day pregnancy rate was greater (P<0.05) for
long (94.5%) postpartum cows compared to
short (70.3%) and medium (76.9%) postpartum
cows, which were similar (P>0.05) to each
other. Body condition score did not (P>0.05)
affect estrous response, timed-AI pregnancy, or
synchronized pregnancy rates, but did affect
conception and 30-d pregnancy rates when
included as a covariate for the main and simple
treatment effects. Cows with a BCS ≥ 5 (64.5%)
tended (P=0.10) to have a greater conception
rate compared to cows with a BCS < 5 (48.6%).
Cows with a BCS ≥ 5 (84.3%) had a greater
(P<0.05) 30-d pregnancy rate compared to cows
with a BCS < 5 (68.6%). Cow age did not affect
(P>0.05) estrous response, conception rate,
timed-AI pregnancy, synchronized pregnancy,
or 30-d pregnancy rates when included as a
covariate for main and simple treatment effects.
The CIDR treatment tended (P=0.10) to
influence conception rate as 14.1% more cows
that received a new CIDR became pregnant
compared to cows that received a once-used
CIDR (Table 3). The interval from PGF2α to
onset of estrus was not (P>0.05) affected by
treatment, with a mean interval of 58.6 ± 10.3 h
across the four treatments. Interval from PGF2α
to onset of estrus did not (P>0.05) effect
conception rates. Conception rates for cows that
exhibited estrus 48, 60 and 72 h after PGF2α
were 61.8 (n=55), 57.6 (n=33), and 60.0%
(n=40), respectively.
In conclusion, synchronized pregnancy rates
were similar between cloprostenol sodium and
dinoprost tromethamine treatments in Select
Synch + CIDR protocols. The decreased estrous
response of the Select Synch + CIDR protocol
compromises the protocols overall effectiveness,
but synchronized pregnancy rates are improved
with addition of a timed-AI after 3 d of estrous
detection. The overall effectiveness of Select
Synch protocols are significantly influenced by
days postpartum at the start of treatment and
producers need to pay particular attention to
when
synchronization
protocols
are
implemented in relation to calving in suckled
Bos indicus  Bos taurus cattle.
Days postpartum affected (P<0.05) estrous
response, conception rate, timed-AI pregnancy,
and synchronized pregnancy rates (Table 4).
Estrous response was greater (P<0.05) for long
(≥ 60 d) compared to short (< 40 d) and medium
(40 to 59 d) postpartum cows, which were
similar (P>0.05) to each other. Conception and
timed-AI pregnancy rates were greater (P<0.05)
for long compared to short postpartum cows, but
were similar (P>0.05) to medium postpartum
cows. Short postpartum cows had similar
(P>0.05) conception and timed-AI pregnancy
rates compared to medium postpartum cows.
Synchronized pregnancy rates were greater
(P<0.05) for long postpartum cows compared to
medium and short postpartum cows (P<0.05)
while the medium postpartum cows had greater
(P<0.05)
synchronized
pregnancy
rates
compared to the short postpartum cows. Thirty-
1
Regina D. Esterman, Graduate Student; Brad R. Austin, Former Graduate Student; Steaven A. Woodall,
Former Graduate Student; Gary R. Hansen, Former Assistant Professor, UF-IFAS North Florida Research
and Education Center, Marianna, FL; Matt Hersom, Assistant Professor; UF-IFAS, Animal Sciences,
Gainesville, FL; Joel V. Yelich, Associate Professor, UF-IFAS Animal Sciences, Gainesville, FL
40
Table 1. Main treatment effects for estrous response, conception rate, and synchronized pregnancy
rate of suckled Bos indicus  Bos taurus cows synchronized with controlled intravaginal progesteronereleasing device (CIDR; new vs once-used) and prostaglandin F2 [(cloprostenol sodium (cloprostenol)
vs dinoprost tromethamine (dinoprost)] treatments (Experiment 1).a
Estrous
response, % (n)b
Conception
rate, % (n)c
Synchronized
pregnancy rate, % (n)d
New CIDR
70.9 (141)
45.0 (100)
31.9 (141)
Once-used CIDR
66.0 (141)
50.5 (93)
33.3 (141)
P-value
P > 0.05
P > 0.05
P > 0.05
Cloprostenol
68.8 (141)
48.5 (97)
33.3 (141)
Dinoprost
68.1 (141)
46.9 (96)
31.9 (141)
P > 0.05
P > 0.05
P > 0.05
Variable
Main effects
P-value
a
All cows received GnRH (100 g) at the initiation of either a 7 d new or once-used CIDR. Cows
received either cloprostenol sodium (500 μg) or dinoprost tromethamine (25 mg) at CIDR removal.
Estrus was detected for 5 d and cows that exhibited estrus were inseminated 8 to 12 h later.
b
Percentage of cows displaying estrus 5 d after prostaglandin F2 of total treated.
c
d
41
Table 2. Effect of days postpartum (DPP) at the initiation of controlled intravaginal progesteronereleasing device (CIDR) and prostaglandin F2 treatments on estrous response, conception rate, and
synchronized pregnancy rates of suckled Bos indicus  Bos taurus cows (Experiment 1).a
DPP
Estrous
response, % (n)b
Conception
rate, % (n)c
Synchronized pregnancy
rate, % (n)d
≤ 50
57.8 (109) e
27.0 (63) e
15.6 (109) e
51-69
64.8 (91) e
49.2 (59) f
31.9 (91) f
≥ 70
86.6 (82) f
64.8 (71) f
56.1 (82) g
a
Estrus was detected for 5 d and cows that exhibited estrus were inseminated 8 to 12 h later.
b
c
d
e,f,g
Means without a common superscript within a column differ (P<0.05)
42
Table 3. Main treatment effects for estrous response, conception rate, timed-AI pregnancy rate, and
synchronized pregnancy rate of suckled Bos indicus  Bos taurus cows synchronized with controlled
intravaginal progesterone-releasing device (CIDR; new vs once-used) and prostaglandin F2
[(cloprostenol sodium (cloprostenol) vs dinoprost tromethamine - (dinoprost)] treatments (Experiment
2).a
Estrous
response, %
(n)b
Conception
rate, % (n)c
Timed-AI
pregnancy
rate, % (n)d
Synchronized
pregnancy rate,
% (n)e
New CIDR
51.2 (125)
67.2 (64)
32.8 (61)
50.4 (125)
Once-used CIDR
49.2 (130)
53.1 (64)
31.8 (66)
42.3 (130)
P > 0.05
P = 0.10
P > 0.05
P > 0.05
Cloprostenol
53.5 (129)
59.4 (69)
28.3 (60)
45.0 (129)
Dinoprost
46.8 (126)
61.0 (59)
35.8 (67)
47.6 (126)
P > 0.05
P > 0.05
P > 0.05
P > 0.05
Variable
Main effects
P-value
P-value
a
Estrus was detected for 3 d and cows exhibiting estrus were AI 8 to 12 h later. Cows not displaying
estrus were timed-AI and received GnRH 76 to 80 h after prostaglandin F2.
b
c
d
e
43
Table 4. Effect of days postpartum (DPP) at the initiation of controlled intravaginal progesteronereleasing device (CIDR) treatments and prostaglandin F2 treatments on estrous response, conception
rate, and pregnancy rates of suckled Bos indicus  Bos taurus cows (Experiment 2).a
DPP
Estrous
Response,
% (n)b
Conception
rate %, (n)c
Timed-AI
pregnancy rate
%, (n)d
Synchronized
pregnancy
rate, % (n)e
< 40
39.2 (74) f
44.8 (29) f
20.0 (45) f
29.7 (74) f
40-59
45.4 (108) f
57.1 (49) f,g
33.9 (59) f,g
44.4 (108) g
≥ 60
68.5 (73) g
72.0 (50) g
52.2 (23) g
65.8 (73) h
a
Estrus was detected for 3 d and cows exhibiting estrus were AI 8 to 12 h later. Cows not displaying
estrus were timed-AI and received GnRH 76 to 80 h after prostaglandin F2.
b
c
d
e
f,g,h
44
100
90
Conception rate, %
80
70
60
50
63.6
50.0
48.9
40
28.6
30
18.2
20
10
0
48
60
72
84
96
Figure 1. Effect of interval from PGF2α to the onset of estrus on conception rates in suckled Bos
indicus  Bos taurus cows synchronized with controlled intravaginal progesterone-releasing device
(CIDR) and prostaglandin F2 treatments. Means between columns without a common letter differ
(P<0.05). Numbers in parenthesis indicate the number of cows inseminated within each category
(Experiment 1).
45
46
Comparison of a Select Synch/CIDR + Timed Artificial Insemination vs a
Modified Co-Synch/CIDR Estrous Synchronization Protocol in Suckled Bos
Indicus Х Bos Taurus Cows
Regina Esterman1
Brad Austin
Erin McKinniss
Joel Yelich
Suckled Bos indicus  Bos taurus cows achieved similar synchronized pregnancy rates when
synchronized with a Select Synch/CIDR + timed artificial insemination (49.4%) vs a modified
Co-Synch/CIDR protocol (47.1%) in a large field trial with 5 groups (n=659).
Summary
Suckled Bos indicus  Bos taurus cows were
used to compare a Select Synch/CIDR + timed
artificial insemination (AI) protocol (SSC) vs a
modified Co-Synch/CIDR protocol (COS). Five
groups of suckled Bos indicus  Bos taurus cows
were evaluated (n=659). Cows received GnRH
and a CIDR on d 0. On d 7, SSC cows had their
CIDR removed and received prostaglandin F2α
(PGF2α), whereas COS cows had their CIDR
removed and received PGF2α on d 7.5. Estrus
was detected for 3 d following PGF2α and SSC
cows were AI 8 to 12 h after observed in estrus.
Cows on the SSC protocol not exhibiting estrus
by 72 h after PGF2α were timed-AI between 76
to 80 h and received GnRH. Estrus was
detected on COS cows, but all COS cows were
timed-AI at 66 h after PGF2α and received
GnRH, regardless of whether they displayed
estrus or not. Similar (P>0.05) synchronized
pregnancy rates were achieved with the SSC
(49.4%; 164/332) and COS (47.1%; 154/327)
protocols. Differences (P<0.05) in estrous
response, timed-AI pregnancy, and synchronized
pregnancy rates were observed between groups.
Days postpartum influenced (P<0.05) timed-AI
pregnancy and synchronized pregnancy rates,
with longer postpartum cows achieving greater
pregnancy rates.
Cycling status did not
(P>0.05) influence synchronized pregnancy
rates. In summary, this field trial suggests that
similar pregnancy rates can be achieved using a
straight timed-AI synchronization protocol
(COS) compared to a heat detection + cleanup
timed-AI protocol (SSC).
Introduction
Development of an estrous synchronization
protocol that achieves acceptable pregnancy
rates in cattle of Bos indicus breeding is
particularly important to producers in
subtropical regions, such as Florida. While there
are many common synchronization protocols,
nearly all of them were developed for Bos taurus
cattle.
A frequently used and effective
synchronization protocol in Bos taurus cattle is
administration of GnRH followed 7 d later with
PGF2α. However, a common problem with the
GnRH + PGF2α protocol is expression of estrus
several days before PGF2α, which can be
eliminated with addition of a progestogen
concomitant with GnRH and removed at PGF2α.
Addition of progestogen can also increase the
percentage of anestrous cows that exhibit estrus.
However, limited research has employed this
protocol in Bos indicus  Bos taurus cattle. The
unpredictability of these synchronization
protocols in cattle of Bos indicus breeding
makes it difficult to utilize a timed-AI program.
Behavioral differences are also apparent in cattle
of Bos indicus breeding, including a shorter, less
evident estrus and increased occurrence of
‘silent estrus’. Due to the difficultly of detecting
47
estrus in these cattle, if a timed-AI protocol
could be refined to produce acceptable
pregnancy rates, the need for estrous detection
would be minimized.
received PGF2α. All cows received an estrous
detection patch (Estrotect™, Rockway, Inc.) at
CIDR removal to aid in estrous detection.
Estrus was visually detected in both treatments
two times daily at 0700 and 1700 h for 3 d
following PGF2α. Estrus was defined as a cow
standing to be mounted by another cow and/or a
half to fully rubbed Estrotect™ patch. Cows in
the SSC treatment were AI 8 to 12 h after
observed in estrus through 72 h post-PGF2α.
Cows in the SSC that had not displayed estrus
by 0800 h, 73 h after PGF2α, were timed-AI and
administered GnRH between 76 and 80 h after
PGF2α. Cows in the COS treatment were all
timed-AI at 66 h after PGF2α and administered
GnRH.
The objective of these experiments were to
evaluate the effectiveness of a Select
Synch/CIDR synchronization protocol followed
by either 3 d of estrous detection with a cleanup
timed-AI at 75 to 80 h or a straight timed-AI at
66 h in postpartum lactating Bos indicus  Bos
taurus cows.
This experiment was conducted from January to
May, 2008 at the Bar L Ranch, Marianna, FL
and the University of Florida Beef Research
Unit, Gainesville, FL.
Five groups of
primiparous and multiparous postpartum
lactating Bos indicus  Bos taurus cows (n=659)
were used. Groups were pre-selected by the
location and initiated the synchronization
protocol once they reached > 45 days
postpartum. Mean ( SD) cow age was 5.3 ±
2.4 yr, DPP was 69.2 ± 15.0 d, body weight
(BW) was 1181 ± 154 lb, and body condition
score was 5.3 ± 0.6 (Table 1; BCS: 1 =
emaciated, 9 = obese). Cycling status, BCS, and
DPP for each group is described in Table 1. The
degree of Bos indicus breeding ranged from
approximately 10 to 75% with the remainder
being Bos taurus breeding. Three groups of
cows were started on the experiment protocol in
three consecutive wk at Bar L Ranch and two
groups were started on the experimental protocol
three wk apart at the Beef Research Unit. On d
0, BW and BCS were evaluated and on d 0 and
10 blood samples were collected for
determination of cycling status. At the start of
the synchronization (d 10), cows were equally
distributed by cow age, DPP, and BCS to one of
two treatments, which included Select
Synch/CIDR + timed-AI (SSC) and a modified
Co-Synch/CIDR (COS) protocol. All cows
received GnRH (100 µg i.m.; Cystorelin®,
Merial) at CIDR (1.38 g progesterone; EaziBreed™ CIDR®, Pfizer Animal Health)
insertion. On d 7, SSC cows’ CIDR were
removed and cows received PGF2α (25 mg i.m.;
Lutalyse®, Pfizer Animal Health). On d 7.5,
COS cows’ CIDR were removed and cows
Frozen-thawed semen from multiple AI sires
was used and cows were inseminated by four AI
technicians. In four of the five groups, 7 d after
the last cow was inseminated, clean-up bulls
were placed with cows. In the remaining group,
estrous detection continued for 30 d and cows
displaying estrus were inseminated a second
time. Pregnancy was diagnosed approximately
55 d after AI using a real-time B-mode
ultrasonography machine
(Aloka
500V,
Corometrics Medical Systems) with a 5.0 MHz
transducer. Due to the 7 d period in which no
cows were inseminated or bred by the clean-up
bull, differences in fetal size were used to
determine whether a pregnancy resulted from
the synchronized breeding or clean-up bull.
Inc.) was used for the statistical analysis of this
experiment. The effects of treatment, group, and
their interaction, were evaluated for estrous
response, conception, timed-AI pregnancy,
synchronized pregnancy, and thirty-day
pregnancy rates. Cow age, DPP, BCS, and
included as covariates. When covariates were
significant (P < 0.05) they were treated as
independent variables.
Results
Estrous response over 3 d following PGF2α for
the SSC cows was 50.6% (168/332) and estrous
response for the 2.5 d following PGF2α for the
48
COS cows was 52.6% (172/327; Table 2).
Estrous response was different (P<0.05) for
groups (data not shown). Estrous response was
influenced (P<0.05) by cycling status at the start
of synchronization (Table 2), with a greater
percent of noncycling cows displaying estrus
(58.2%; 170/292) compared to cycling cows
(46.3%; 170/367). Days postpartum effected
(P<0.05) estrous response (Table 3). Cows that
were ≤ 55 DPP had a lower (P<0.05) estrous
response compared to cows that were ≥ 56 DPP.
Cows that were 56 to 65 DPP had a lower
(P<0.05) estrous response compared to cows
that were 66 to 75 DPP, but were similar
(P>0.05) to cows ≥ 76 DPP. Cows 66 to 75
DPP and ≥ 76 DPP had a similar (P>0.05)
estrous response.
Body condition score
influenced (P<0.05) estrous response (Table 4).
Cows with a BCS ≤ 4.5 had a lower (P<0.05)
estrous response compared to cows with 5 to 5.5
BCS or ≥ 6 BCS. Cows with a BCS of 5 to 5.5
or ≥ 6 had a similar (P>0.05) estrous response.
There were no (P>0.05) effects of age on estrous
response. In SSC cows that displayed estrus, the
interval from PGF2α to the onset of estrus was
59.1 ± 0.7 h. In COS cows that displayed estrus,
the interval from PGF2α to the onset of estrus
was 51.0 ± 0.7 h.
cows that were 56 to 65 DPP and 66 to 75 DPP,
but were similar to cows ≥ 76 DPP. Cows 56 to
65 DPP and 66 to 75 DPP had similar (P>0.05)
timed-AI pregnancy rates, but were both greater
(P<0.05) than cows that were ≥ 76 DPP.
Timed-AI pregnancy rate was not (P>0.05)
effected by cycling status, age, or BCS.
Synchronized pregnancy rates were similar
(P>0.05) for SSC (49.4%; 164/332) and COS
(47.1%; 154/327) treatments (Table 2). Groups
differed (P<0.05) in synchronized pregnancy
rates (data not shown). Cycling status did not
(P>0.05) influence overall synchronized
pregnancy rates. Days postpartum influenced
(P<0.05) synchronized pregnancy rates (Table
3). Cows that were ≤ 55 DPP had lower
(P<0.05)
synchronized
pregnancy
rates
compared to cows that were 56 to 65 DPP and
66 to 75 DPP, but were similar (P>0.05) to cows
that were ≥ 76 DPP. Cows 56 to 65 DPP and 66
to 75 DPP had similar (P>0.05) synchronized
pregnancy rates, as did cows that were 65 to 75
DPP and ≥ 76 DPP. Cows that were 66 to 75
DPP and ≥ 76 DPP had similar (P>0.05)
synchronized pregnancy rates. Body condition
score influenced (P<0.05) synchronized
pregnancy rates (Table 4). Cows with a BCS ≤
4.5 (39.0; 46/118) had lower (P<0.05)
synchronized pregnancy rates compared to cows
with 5 to 5.5 BCS (48.8%; 183/375) or ≥ 6 BCS
(53.6%; 89/166). Cows with a BCS of 5 to 5.5
or ≥ 6 had similar (P>0.05) synchronized
pregnancy rates. Synchronized pregnancy rate
was not (P>0.05) influenced by cow age.
The conception rate for SSC cows was 66.1%
(111/168; Table 2). Conception rate was not
(P>0.05) effected by group. Cycling status, age,
and DPP did not (P>0.05) effect conception rate
in SSC cows.
In SSC cows that did not display estrous and
were timed-AI, timed-AI pregnancy rate
averaged 32.3% (53/164) across all groups
(Table 2). In COS cows, all cows were timedAI and the timed-AI pregnancy rate averaged
47.1% (154/327) across all groups. Timed-AI
pregnancy rates differed (P<0.05) between
groups (data not shown). Days postpartum
influenced (P<0.05) timed-AI pregnancy rate
(Table 3). Cows that were ≤ 55 DPP had lower
(P<0.05) timed-AI pregnancy rates compared to
In summary, similar synchronized pregnancy
rates were achieved using the SSC and COS
synchronization protocols.
Differences in
estrous response, timed-AI pregnancy, and
synchronized pregnancy rates were observed
between groups.
Cycling status did not
influence pregnancy rates, however DPP did
effect pregnancy rates.
1
Regina Esterman; Graduate Student; Brad Austin, Graduate Student; Erin McKinniss; Graduate
Student; Joel Yelich Associate Professor, UF-IFAS Animal Sciences, Gainesville, FL
49
Table 1 General description of Bos indicus  Bos taurus cows synchronized with either a Select
Synch/CIDR + TAI or modified Co-Synch/CIDR synchronization protocol by group.a
Group
n
1
173
2
152
3
193
4
94
5
47
Cycling Status
(%)
Approx. %
Brahman breeding
(%)
Body condition
score, 1-9, (range)
Days postpartum,
(range)
59.0 (173)
10 - 38
5.4 ± 0.05
(3.5 - 7.0)
74.0 ± 1.1
(48 - 128)
38.2 (152)
10 - 38
5.2 ± 0.05
(4.0 - 7.0)
75.4 ± 1.2
(47 - 102)
59.6 (193)
10 - 38
5.5 ± 0.05
(4.0 - 7.0)
62.8 ± 1.0
(54 - 99)
64.9 (94)
25 - 75
5.1 ± 0.1
(3.5 - 6.5)
71.3 ± 1.4
(50 - 99)
66.0 (47)
25 - 75
5.1 ± 0.1
(3.5 - 6.5)
53.8 ± 2.0
(41 - 69)
a
All cows received GnRH at initiation of the 7 d CIDR treatment, with PGF2 administered at the time of
CIDR removal. For Select Synch/CIDR + TAI cows, estrus was detected for 3 d, and cows that exhibited
estrus were AI approximately 8 to 12 h later. Cows which had not displayed estrus were timed-AI at 76 to
80 h and given GnRH. All modified Co-Synch/CIDR cows were fixed TAI at 66 h after PGF2.
50
Table 2 Effect of synchronization protocol (Select Synch/CIDR + timed-AI (SCC) or modified CoSynch/CIDR (COS)) and cycling status on estrous response, conception, timed-AI pregnancy, and
synchronized pregnancy rates following PGF2 in Bos indicus  Bos taurus cows.a
n
Estrous
response, %b
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Synchronized
pregnancy rate,
%e
332
50 .6 (332)
66.1 (168)
32.3 (164)
49.4 (332)
185
48.8 (185)
66.7 (81)
40.4 (104)
51.9 (185)
147
59.2 (147)
65.5 (87)
18.3 (60)
46.3 (147)
327
52.6 (327)
.
47.1 (327)
47.1 (327)
182
48.9 (182)
.
45.1 (182)
45.1 (182)
145
57.2 (145)
.
49.7 (145)
49.7 (145)
Treatment
P > 0.05
.
.
P > 0.05
Cycling Status
P < 0.05
P > 0.05
P > 0.05
P > 0.05
Treatment  Cycling
P > 0.05
.
.
P > 0.05
Treatment
SSC
Cycling
Non-cycling
COS
Cycling
Non-cycling
P Values
a
b
Percentage of cows displaying estrus 3 d after PGF2 of total treated.
c
d
e
51
Table 3 Effect of days postpartum (DPP) on estrous response, conception, timed-AI pregnancy, and
synchronized pregnancy rates following PGF2 in Bos indicus  Bos taurus cows synchronized with
either a Select Synch/CIDR + timed-AI (SCC) or modified Co-Synch/CIDR (COS) synchronization
protocol.a
DPP
n
Estrous
response, %b
≤ 55 d
96
35.4 (96)f
70.6 (17)
31.6 (79)f,h
38.5 (96)f
228
50.4 (228)g
70.4 (54)
47.7 (174)g
53.1 (228)g
148
60.1 (148)h
56.5 (46)
50.0 (102)g
52.0 (148)g,h
136
54.6 (187)g,h
68.6 (51)
35.3 (136)h
44.4 (187)f,h
P < 0.05
P > 0.05
P < 0.05
P < 0.05
56 - 65
66 - 75
≥ 76 d
P Values
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Synchronized
pregnancy rate,
%e
a
b
c
d
e
f,g,h
52
Table 4 Effect of body condition score (BCS) on estrous response, conception, timed-AI pregnancy,
and synchronized pregnancy rates following PGF2 in Bos indicus  Bos taurus cows synchronized
with either a Select Synch/CIDR + timed-AI (SCC) or modified Co-Synch/CIDR (COS)
synchronization protocol.a
BCS
n
Estrous
response, %b
≤ 4.5
118
41.5 (118)f
54.6 (22)
35.4 (96)
39.0 (118)f
375
53.6 (375)g
63.7 (102)
43.2 (273)
48.8 (375)g
166
54.2 (166)g
77.3 (44)
45.1 (122)
53.6 (166)g
P = 0.05
P > 0.05
P > 0.05
P < 0.05
5 - 5.5
≥6
P Values
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Synchronized
pregnancy rate,
%e
a
b
c
d
e
f,g
53
54
Comparison of Two Progestogen Based Estrous Synchronization Protocols
and Cloprostenol Sodium vs. Dinoprost Tromethamine in Suckled Post
Partum Cows and Yearling Heifers of Bos Indicus × Bos Taurus Breeding
Erin McKinniss1
Regina Esterman
Steaven Woodall
Brad Austin
Joel Yelich
Synch/CIDR+timed-AI had increased conception and synchronized pregnancy rates compared to the
7-10 treatment in suckled cows of Bos indicus × Bos taurus breeding. Body condition score and
days postpartum influenced the effectiveness of the synchronization treatments. There were no
synchronization or prostaglandin treatment effects on any of the reproductive responses measured in
the yearling heifers of Bos indicus × Bos taurus breeding.
Summary
Bos indicus × Bos taurus suckled postpartum
cows (n=324) and yearling heifers were utilized
over two breeding seasons (n=218 and 137) in
an experiment comparing two progestogen
based synchronization protocols and two
prostaglandins. On d 0, the 7-10 treatment
received an autoclaved once used Eazi breed
CIDR progesterone insert (CIDR) that was
removed on d 7 concomitant with Dinoprost
tromethamine (Prostamate) followed by
gonadotropin releasing hormone (GnRH) on d
10. On d 17, 7-10 treatment received one of two
prostaglandins, Prostamate or Cloprostenol
sodium (Estrumate). Also on d 10, the Select
Synch/CIDR+timed-artificial insemination (AI)
treatment received a new CIDR concomitant
with GnRH with CIDR removal on d 17 where
cows received either Prostamate or Estrumate.
Estrus was visually detected twice daily (0700
and 1600 h) for 72 h after prostaglandin F2α
(PGF2α) and cows were AI 6 to 12 h after a
detected estrus. Non-responders were timed-AI
+ GnRH 72 to 76 h post PGF2a.
Synch/CIDR+timed-AI and 7-10 treatments,
respectively. As body condition score (BCS)
increased from ≤ 4.5 to ≥ 5.5, estrous response,
conception rate, synchronized pregnancy rate,
and 30-d pregnancy rates increased (P < 0.05).
For the heifers, estrous response, conception
rate, timed-AI pregnancy rates, synchronized
pregnancy rate, and 30-d pregnancy rates were
similar (P > 0.05) between the synchronization
and PGF2α treatments, with the mean estrous
response, conception rate, timed-AI pregnancy
rates, synchronized pregnancy rate, and 30 d
pregnancy rates being 66.8, 65.0, 16.1, 48.7,
and 76.3%, respectively.
Introduction
One of the most consistent synchronization
protocols in suckled cows and yearling heifers of
Bos taurus breeding includes administration of a
7 d Eazi-Breed™ CIDR® with GnRH at CIDR
insertion and PGF2α at CIDR removal, followed
by 3 d of estrous detection and AI with a timedAI plus GnRH for cattle not exhibiting estrus by
72 h after PGF2α. This protocol is known as the
Select
Synch/CIDR+timed-AI
protocol.
Previous reports indicated pregnancy rates were
similar for suckled cows and yearling heifers of
Bos indicus × Bos taurus breeding compared to
For the cows, estrous response, conception rate,
and synchronized pregnancy rate synchronized
pregnancy rate were affected (P < 0.05) by
synchronization treatment but not (P > 0.05)
PGF2 treatment. The synchronized pregnancy
rates were 45.5% and 31.2 for the Select
55
cattle of Bos taurus breeding.
Therefore,
additional experiments are needed in cattle of
Bos indicus × Bos taurus breeding to evaluate
CIDR synchronizations treatments when GnRH
is administered at CIDR insertion and at timedAI for induction of ovulation in cows not
expressing estrus.
were to evaluate the effectiveness of Prostamate
compared to Estrumate when used in a modified
7-11 protocol and a Select Synch/CIDR+timedAI protocol in yearling heifers and suckled cows
of Bos indicus × Bos taurus breeding.
Procedure
Suckled cows of Bos indicus × Bos taurus (n =
324) in 2007, and yearling heifers in 2006 and
2007(n = 218 and 137) from Bar-L Ranch in
Marianna, FL, were used for the experiments.
Genotypes for the animals utilized ranged from
approximately 7 to 38% Bos indicus with the
remainder being Bos taurus genotype.
The 7-11 synchronization protocol is another
short-term progestogen synchronization protocol
that is frequently used in cattle of Bos taurus
breeding. The 7-11 protocol consists of a 7 d
melengestrol acetate (MGA) treatment with
PGF2α on the last day of MGA followed by
GnRH 4 d later. Seven-d after GnRH, PGF2α is
administered to synchronize estrus. The 7-11
synchronization protocol is effective in Bos
taurus cattle but no research has been conducted
to evaluate the effectiveness of the 7-11 protocol
in yearling heifers of Bos indicus × Bos taurus
breeding and one study has been conducted in
suckled cows of Bos indicus × Bos taurus
breeding.
At the start of the experiment (d 0), cows were
equally distributed by body condition score
(BCS; 1 = emaciated, 5 = moderate, 9 = very fat)
and days post partum (DPP) to one of two
progestogen based synchronization treatments
and one of two PGF2α treatments (Figure 1).
The synchronization treatments included a
modified 7-11 treatment, (7-10) and the Select
Synch/CIDR+timed-AI treatment. Within each
synchronization treatment, half the cows
received one of two PGF2α treatments:
Prostamate (25 mg i.m.; Agrilabs) or Estrumate
(500 µg i.m.; Schering-Plough Veterinary
Corp.). On d 0, the 7-10 treatment received an
autoclaved once-used CIDR (Eazi-Breed™
CIDR®, 1.38 g progesterone, Pfizer Animal
Health) that was removed on d 7 concomitant
with Prostamate followed by GnRH (500 µg;
Cystorelin®, Merial Animal Health) on d10. The
once-used autoclaved CIDR was used in place of
MGA to test its effectiveness as a low cost
alternative progestogen source in the 7-10
protocol. On d17, 7-10 cows received either
Prostamate or Estrumate. Also on d 10, the
Select
Synch/CIDR+timed-AI
treatment
received a new CIDR concomitant with GnRH
followed by CIDR removal on d 17 where cows
received either Prostamate or Estrumate.
As production costs increase, producers seek to
implement new management practices that either
reduce their operating costs and (or) increase
productivity.
Therefore, there has been
considerable interest in using a once-used CIDR
in estrous synchronization protocols. Previous
reports indicate utilization of a once-used CIDR
for 7 d suppresses estrus in beef females and
autoclaving a once-used CIDR increases
circulating
progesterone
concentrations
compared to a non-autoclaved once-used CIDR.
Autoclaving also reduces the risk of disease
transmission. Therefore, there appears to be
potential for incorporating a once-used CIDR
into some estrous synchronization protocols.
Additionally, a minimal amount of research has
been conducted evaluating the effectiveness of
prostaglandin type; Prostamate compared to
Estrumate, when used in GnRH+PGF2α estrous
synchronization protocols in cattle of Bos
indicus × Bos taurus breeding. Additionally, no
direct comparisons have been made between
Prostamate and Estrumate in yearling Bos
indicus × Bos taurus heifers synchronized with
GnRH+PGF 2α synchronization protocols.
To aid in estrous detection, all cows received
Estrotect™ estrous detection patches (Rockway,
Inc.) on d 18 of the experiment. Estrus was
visually detected twice daily (0700 and 1600 h)
for 72 h after PGF2α and cows were inseminated
56
6 to 12 h after detection of estrus. Nonresponders were timed-AI + GnRH 72 to 76 h
post PGF2α. Seven-d after the timed-AI, natural
service sires were placed with cows. Pregnancy
was diagnosed approximately 55 d after AI by
transrectal ultrasonography.
In both years, heifers had similar (P > 0.05)
estrous response, conception rate, timed-AI
pregnancy rate, synchronized pregnancy rate,
and 30 d pregnancy rate between 7-10 vs. Select
Synch/CIDR+timed-AI (Table 2) and Estrumate
vs.Prostamate (Table 3). Across treatments, the
mean estrous response, conception rate, timedAI pregnancy rate, synchronized pregnancy rate
and 30 d pregnancy rate were 66.8, 65.0, 16.1,
48.7, and 76.3% respectively.
The mean
synchronized pregnancy rate for the Prostamate
and Estrumate treatments were 45.5 and 52.0%,
respectively. At 48 h after PGF2α, treatments
had a similar (P > 0.05) conception rate. At 60
h, Select Synch/CIDR+timed-AI treatment
tended (P = 0.10) to have a decreased
conception rate. Inversely, at 72 h, Select
Synch/CIDR+timed-AI treatment had an
increased (P < 0.05) conception rate compared
to the 7-10 treatment.
Estrous response was defined as the number of
cows displaying estrus for 3 d after
prostaglandin and AI divided by the total
number of cows treated. Conception rate was
defined as the number of cows that became
pregnant to AI divided by the number of cows
that displayed estrus and were AI. Timed-AI
pregnancy rate was the number of cows that
failed to display estrus, were timed-AI, and
became pregnant divided by the total number of
cows that were timed-AI.
Synchronized
pregnancy rate was the number of cows pregnant
to AI divided by the total number of cows
treated. Thirty-d pregnancy rate was the number
of cows pregnant during the first 30 d of the
breeding season divided by the total number of
cows treated.
In summary, the Select Synch/CIDR+timed-AI
had increased conception and synchronized
pregnancy rates compared to the 7-10 treatment
in suckled cows of Bos indicus × Bos taurus
breeding. The effectiveness of the treatment
was influenced by BCS, as BCS increased, the
estrous response, conception rate, and
synchronized pregnancy rates increased. Days
postpartum also influenced effectiveness of the
synchronization treatments, as time from calving
to start of synchronization increased,
synchronized pregnancy rates increased. There
was no effect of prostaglandin treatment on
estrous response, conception rate, timed-AI
pregnancy rate, synchronized pregnancy rate, or
30 d pregnancy rate.
There were no
synchronization or prostaglandin treatment
effects on any of the reproductive responses
measured in the yearling heifers of Bos indicus
× Bos taurus breeding for either year.
Yearling heifers were randomly assigned to the
same treatments and estrous detection and AI
were administered in the same manner as for the
cows.
Results and Discussion
For the cows, estrous response, conception rate,
and synchronized pregnancy rate was affected
(P < 0.05) by synchronization treatment (Table
1). Body condition score also affected (P <
0.05) estrous response, conception rate, and
synchronized pregnancy rate, and 30 d
pregnancy rates. Days postpartum tended to (P
= 0.1) effect timed-AI pregnancy rate and had an
effect (P < 0.05) on synchronized pregnancy
rate. Prostaglandin treatments were similar (P >
0.05) for estrous response, conception rate,
timed-AI
pregnancy
rate,
synchronized
pregnancy rate, and 30 d pregnancy rate (Table
1).
1
Erin McKinniss, Graduate Student; Regina Esterman, Graduate Student; Steaven Woodall, Former
Graduate Student; Brad Austin, Graduate Student, Department of Animal Sciences, Gainesville, FL;
Joel Yelich, Professor, UF-IFAS Department of Animal Sciences, UF, Gainesville, FL
57
a) 7-10 treatment with Prostamate or Estrumate PGF2α on d 17
Prostamate
Prostamate or
Estrumate
GnRH
Once-used CIDR
GnRH +
timed-AI
Estrus detect & AI
b) Select Synch/CIDR+timed-AI treatment with Prostamate or Estrumate PGF2α on d 17
Prostamate or
Estrumate
GnRH
New CIDR
0
Figure 1.
7
10
Day of experiment
GnRH +
timed-AI
Estrus detect & AI
17
20
Experimental design evaluating the effects of two progestogen and two PGF2α treatments in Bos
indicus × Bos taurus suckled cows and yearling heifers a) 7-10 treatment: on d 0 received a onceused CIDR that was removed on d 7 concomitant with Prostamate (25 mg i.m.) followed by
GnRH (500 µg i.m.) on d 10. On d 17, females received either Prostomate or Estrumate (500 µg
i.m.). b) Select Synch/CIDR+timed-AI treatment: on d 10 received a new CIDR (1.38 g)
concomitant with GnRH. Day 17 CIDR was removed and females received either Prostomate or
Estrumate. For all four treatments estrus was detected for 3 d and females were inseminated 6 to
12 h after detected estrus. Females not exhibiting estrus by 72 h were timed-AI and received
GnRH.
58
Table 1. Effect of synchronization treatment and prostaglandin treatment on estrous response,
conception rates and pregnancy rates in suckled cows of Bos indicus × Bos taurus breeding
synchronized with either a modified 7-11 (7-10) or Select Synch/CIDR+timed-AI (SSC+TAI)
treatment with either Estrumate or Prostamate.a
Estrous
response, %b
Conception
rate, %c
Timed-AI
pregnancy rate,
%d
7-10
49.0 (77/157)
45.5 (35/77)
17.5 (14/80)
31.2 (49/157)
SSC+TAI
59.9 (100/167)
62.0 (62/100)
20.9 (14/67)
45.5 (76/167)
P-value
< 0.05
< 0.05
> 0.05
< 0.05
Estrumate
57.0 (94/165)
48.9 (46/94)
23.9 (17/71)
38.2 (63/165)
Prostamate
52.2 (83/159)
61.5 (51/83)
14.5 (11/76)
39.0 (62/159)
P-value
> 0.05
> 0.05
> 0.05
> 0.05
Variable
Synchronized
pregnancy rate, %e
Synchronization
Prostaglandin
a
See Figure 3-1 for details of treatments.
b
Percentage of cows displaying estrus 72 h after PGF2 of the total treated.
c
d
e
59
Table 2. Estrous response, conception, and pregnancy rates by synchronization treatment of yearling
heifers of Bos indicus × Bos taurus genotype synchronized with either a modified 7-11 (7-10) or Select
Synch/CIDR+timed-AI (SSC+TAI) treatment with either Estrumate or Prostamate for years 1 and 2.a
Estrous response,
%b
Conception rate,
%c
Timed-AI
pregnancy rate %d
Synchronized
pregnancy rate, %e
7-10
65.2 (116/178)
62.1 (72/116)
14.5 (9/62)
45.5 (81/178)
Yr 1
71.6 (78/109)
65.4 (51/78)
9.68 (3/31)
49.5 (54/109)
Yr 2
55.1 (38/69)
55.3 (21/38)
19.4 (6/31)
39.1 (27/69)
SSC+TAI
68.4 (121/177)
67.8 (82/121)
17.9 (10/56)
52.0 (92/177)
Yr 1
64.2 (70/109)
71.4 (50/70)
20.5 (8/39)
53.2 (58/109)
Yr 2
75.0 (51/68)
62.7 (32/51)
11.8 (2/17)
50.0 (34/68)
Sync
> 0.05
> 0.05
> 0.05
> 0.05
Yr
> 0.05
> 0.05
> 0.05
> 0.05
Sync ×Yr
< 0.05
> 0.05
> 0.05
> 0.05
Variable
P-value
a
b
Percentage of heifers displaying estrus 72 h after PGF2 of the total treated.
c
Percentage of heifers pregnant to AI of the total that exhibited estrus and were AI.
d
Percentage of heifers pregnant to timed-AI of the total that were timed-AI.
e
Percentage of heifers pregnant during the synchronized breeding of the total treated.
60
Table 3. Estrous response, conception and pregnancy rates by prostaglandin treatment of yearling
heifers of Bos indicus × Bos taurus genotype synchronized with either a modified 7-11 (7-10) or Select
Synch/CIDR + timed-AI (SSC+TAI) treatment with either Estrumate or Prostamate for yr 1 and 2.a
Variable
Estrous
response, %b
Conception rate,
%c
Timed-AI
pregnancy rate,
%d
Estrumate
68.7 (123/179)
67.5 (83/123)
17.9 (10/56)
52.0 (93/179)
Yr 1
70.6 (77/109)
71.4 (55/77)
18.8 (6/32)
56.0 (61/109)
Yr 2
65.7 (46/70)
60.9 (38/46)
16.7 (4/24)
45.7 (32/70)
Prostamate
64.8 (114/176)
62.3(71/114)
14.5 (9/62)
45.4 (80/176)
Yr 1
65.1 (71/109)
64.8 (46/710
13.2 (5/38)
46.8 (51/109)
Yr 2
64.2 (43/67)
58.1 (25/43)
16.7 (4/24)
43.3 (29/67)
Prostaglandin
> 0.05
> 0.05
> 0.05
> 0.05
Yr
> 0.05
> 0.05
> 0.05
> 0.05
Prostaglandin ×
Yr
> 0.05
> 0.05
> 0.05
> 0.05
Synchronized
pregnancy rate, %e
P-value
a
b
Percentage of heifers displaying estrus 72 h after PGF2 of the total treated.
c
d
Percentage of heifers pregnant to timed-AI of the total that were timed-AI.
e
Percentage of heifers pregnant during the synchronized breeding of the total treated.
61
62
Effectiveness of Cloprostenol Sodium vs. Dinoprost Tromethamine in a
GnRH/CIDR + PGF2α Synchronization Protocol in Angus, Brahmans, and
Brahman  Angus Cows
Regina Esterman1
Brad Austin
Steaven Woodall
Erin McKinniss
Joel Yelich
Suckled Bos taurus, Bos indicus, and Bos indicus  Bos taurus cows had similar estrous responses,
conception, timed-AI pregnancy, and synchronized pregnancy rates when synchronized with a Select
Synch/CIDR + timed artificial insemination protocol with two PGF2α types. The cloprostenol sodium
PGF2α treatment tended to yield greater estrous response, timed-AI pregnancy, and synchronized
pregnancy rates compared to dinoprost tromethamine.
Summary
Suckled Bos taurus, Bos indicus, and Bos
indicus  Bos taurus cows were used to evaluate
the
Select
Synch/CIDR
(intravaginal
progesterone releasing device) + timed artificial
insemination (TAI) synchronization protocol
with two prostaglandin F2α (PGF2α) types
(cloprostenol
sodium
vs.
dinoprost
tromethamine). Cows received GnRH and a
CIDR on d 0, followed by CIDR removal and
either cloprostenol sodium or dinoprost
tromethamine on d 7. Estrus was detected for 3
d following PGF2α and cows were AI 8 to 12 h
after observed in estrus. Cows not exhibiting
estrus by 72 h after PGF2α were timed-AI
between 76 to 80 h and received GnRH. Six
breeds were evaluated, including: Angus, ¾
Angus ¼ Brahman, ⅝ Angus ⅜ Brahman
(Brangus), ½ Angus ½ Brahman, ¼ Angus ¾
Brahman, and Brahman. Cloprostenol treated
cows tended to have a greater estrous response
(P=0.17), timed-AI pregnancy rate (P=0.09),
and synchronized pregnancy rate (P=0.15).
Breed of the cow did not (P>0.05) influence
estrous response, conception rate, or timed-AI
pregnancy rate, but tended (P=0.15) to
influence synchronized pregnancy rate. Year of
replication effected conception rate and
synchronized pregnancy rate, but only tended to
influence estrous response (P=0.07) and timedAI pregnancy rate (P=0.14). In summary, the
PGF2α treatment of cloprostenol sodium tended
to yield greater responses compared to
dinoprost tromethamine when used in the Select
Synch + timed-AI protocol and the response to
synchronization treatment was similar among
Bos taurus, Bos indicus, and Bos indicus  Bos
taurus breeds.
Introduction
Cattle of Bos indicus breeding are commonly
used by producers in tropical and subtropical
regions of the world due to their superior
tolerance to high temperatures, humidity,
parasites, and utilization of low quality forages
compared to Bos taurus cattle.
Slight
differences in the reproductive physiology of
Bos indicus compared to Bos taurus cattle
include a reduced capacity for luteinizing
hormone (LH) secretion, an earlier LH surge and
ovulation relative to the onset of estrus, and a
greater sensitivity to exogenous gonadotrophins.
Behavioral differences are also apparent in Bos
indicus cattle, including a shorter, less evident
estrus and increased occurrence of ‘silent
estrus’.
Utilization of the estrous synchronization
protocol of GnRH followed 7 d later by PGF2α is
commonly used in Bos taurus cows. A common
problem with the GnRH + PGF2α system is
63
expression of estrus several days prior to PGF2α,
which can be prevented with the addition of a
progestogen between the GnRH and PGF2α
treatments. Addition of a progestogen like
melengestrol acetate or the intravaginal
progesterone releasing device (CIDR) to the
GnRH + PGF2α system can also have a
beneficial effect by increasing the number of
anestrous cows that exhibit estrous cycles.
Studies using the GnRH + PGF2α systems with
or without a progestogen have been conducted in
Bos indicus  Bos taurus cattle with limited
success.
¾ Brahman. On d 0, all cows received GnRH
(100 µg i.m.; Fertagyl®, Intervet) and a new
CIDR (1.38 g progesterone; Eazi-Breed™
CIDR®, Pfizer Animal Health). On d 7, CIDR
was removed and cows were equally distributed
by breed and DPP to receive either of two PGF2α
treatments, which included cloprostenol sodium
(500 µg i.m.; Estrumate®, Schering-Plough
Veterinary Corp.) or dinoprost tromethamine (25
mg i.m.; Lutalyse®, Pfizer Animal Health). All
cows also received an Estrotect™ estrous
detection patch (Estrotect™, Rockway, Inc.).
Estrus was visually detected three times daily at
0700, 1200, and 1700 h for 3 d following PGF2α.
Estrus was defined as a cow standing to be
mounted by another cow and/or a half to full red
Estrotect™ patch.
Cows were artificially
inseminated (AI) 8 to 12 h after an observed
estrus. All cows that had not displayed estrus by
0800 h, 73 h after PGF2α were timed-AI and
administered GnRH between 76 and 80 h after
PGF2α.
The effectiveness of prostaglandins like
cloprostenol
sodium
and
dinoprost
tromethamine to synchronize estrus has been
well documented in Bos taurus cattle, but only
one comparison in cattle of Bos indicus breeding
has been conducted.
was to evaluate the effectiveness of two PGF2α
treatments, cloprostenol sodium and dinoprost
tromethamine, in a GnRH + PGF2α
synchronization program combined with a CIDR
for synchronizing heifers and postpartum
lactating cows, and to evaluate breed effects for
cows of Angus (Bos taurus), Brahman (Bos
indicus), and Brahman  Angus breeding for
responses to the GnRH + PGF2α synchronization
program.
Cows were inseminated using frozen-thawed
semen from multiple pre-assigned sires and were
inseminated by three AI technicians. Pregnancy
was diagnosed approximately 29 d after
insemination using a real-time B-mode
ultrasound (Aloka 500V, Corometrics Medical
Systems) with a 5.0 MHz transducer.
Inc.) was used for the statistical analysis. The
effects of PGF2α treatment, breed, year, and all
appropriate interactions were evaluated for
estrous
response,
conception,
timed-AI
pregnancy, and synchronized pregnancy rates.
Days postpartum, BCS and cow age were
included as covariates for the evaluation of
estrous
response,
conception,
timed-AI
pregnancy, and synchronized pregnancy rates.
This experiment was conducted over a three year
period from February to May of 2005 to 2007 at
the University of Florida, Department of Animal
Sciences Beef Research Unit. Multiparous,
postpartum, lactating cows of varying degrees of
Brahman (Bos indicus) and Angus (Bos taurus)
breeding (n=504) were used. Cows had a mean
(± SD) age of 5.1 ± 2.4 yr, days postpartum
(DPP) of 65.5 ± 16.2 d, body weight (BW) of
1,208 ± 139 lb, and body condition score (BCS)
of 5.2 ± 0.6 (1 = emaciated, 9 = obese). Breed
types represented included Angus, Brahman, and
different percentages of Brahman  Angus
breeding. The Brahman  Angus cows were ¾
Angus ¼ Brahman, ⅝ Angus ⅜ Brahman
(Brangus), ½ Angus ½ Brahman, and ¼ Angus
Results
Estrous response tended (P=0.17) to be greater
for cloprostenol treated cows compared to
dinoprost treated cows (Table 1). Estrous
response tended (P=0.07) to differ between
years of replication (Table 2), but estrous
response was not influenced (P>0.05) by breed
64
by yr of replication (Table 2). Breed did not
(P>0.05) effect timed-AI pregnancy rate (Table
3). There were no PGF2α treatment  breed,
PGF2α treatment  year, breed  year, or PGF2α
treatment  year  breed effects (P>0.05) on
timed-AI pregnancy rate. Cow age and DPP did
not (P>0.05) influence timed-AI pregnancy rate.
(Table 3). There were no PGF2α treatment 
breed, PGF2α treatment  year, or breed  year
effects (P>0.05) on estrous response. Cow age
affected (P<0.05) estrous response. Three-year
old cows (44.4%) had a decreased (P<0.05)
estrous response compared to cows that were 4
to 5 yr (57.1%), 6 to 7 yr (59.2%), and 8 to 16 yr
(59.7%), which had similar (P>0.05) estrous
responses.
Days postpartum also tended
(P=0.06) to affect estrous response. Short (≤ 55
d) DPP cows had a lower (P<0.05) estrous
response (45.4%) than medium (56 to 74 d) DPP
cows (58.3%), but were similar (P>0.05) to long
(≥ 75 d) postpartum cows (54.6%). Medium
DPP cows had a similar (P>0.05) estrous
response compared to long DPP cows. Body
condition score did not (P>0.05) influence
estrous response. The average interval from
PGF2α to the onset of estrus was not effected
(P>0.05) by PGF2α treatment or breed of cow,
nor did it effect (P>0.05) conception rates. For
cows that exhibited estrus, the average interval
from PGF2α to the onset of estrus was 54.7 ± 9.4
h.
Synchronized pregnancy rate tended (P=0.15) to
be effected by PGF2α treatment (Table 1).
Cloprostenol treated cows tended (P=0.15) to
have greater synchronized pregnancy rates
compared to dinoprost treated cows (Table 1).
Synchronized pregnancy rates were greater
(P<0.05) for yr 1 compared to yr 2 and 3, which
were similar (P>0.05) to each other (Table 2).
Breed tended (P=0.15) to effect overall
synchronized pregnancy rates (Table 3). There
were no PGF2α treatment  breed, PGF2α
treatment  year, breed  year, or PGF2α
treatment  year  breed effects (P>0.05) on
synchronized pregnancy rate. Synchronized
pregnancy rates were greater (P < 0.01) for yr 1
compared to yr 2 (Table 2). Age did not
(P>0.05) influence synchronized pregnancy.
Synchronized pregnancy rate was greater
(P<0.05) for medium (54.0%) and long (54.6%)
DPP cows compared to short (40.8%) DPP
cows. Long DPP cows had similar (P>0.05)
synchronized pregnancy rates to medium DPP
cows.
Conception rate was similar (P>0.05) between
PGF2α treatments (Table 1) and breed of cow
(Table 3). However, each year of replication
had different (P<0.05) conception rates from the
other years (Table 2). There were no PGF2α
treatment  breed, PGF2α treatment  year, breed
 year, or PGF2α treatment  year  breed effects
(P>0.05) on conception rate. Days postpartum
influenced (P<0.05) conception rate. Long
(70.8%) and medium (61.8%) DPP cows had a
similar (P>0.05) conception rate, which was a
greater (P<0.05) compared to short (49.2%)
DPP cows. Short DPP cows had a similar
(P>0.05) conception rate compared to medium
DPP cows. Cow age and BCS did not (P>0.05)
influence conception rate.
The overall estrous response, conception rate,
timed-AI pregnancy rate, and synchronized
pregnancy rate pooled across both PGF2α
treatments were 53.8, 62.0, 37.8, and 50.8%,
respectively. Breed of cow did not influence
(P>0.05) estrous response, conception rate, or
timed-AI pregnancy rates, but tended (P=0.15)
to influence synchronized pregnancy rates.
Timed-AI pregnancy rates tended (P=0.09) to be
greater for cloprostenol treated cows compared
to dinoprost treated cows (Table 1). Timed-AI
pregnancy rate tended (P=0.14) to be influenced
1
Regina Esterman, Graduate Student; Brad Austin, Graduate Student; Steaven Woodall, Former
Graduate Student; Erin McKinniss, Graduate Student; Joel Yelich; Associate Professor, UF-IFA,
Department of Animal Sciences, Gainesville, FL
65
Table 1 Estrous, conception, and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos
taurus cows synchronized with a 7 d CIDR treatment with two different prostaglandin F2 (PGF2)
treatments administered at CIDR removal.a
N
3 d Estrous
Response
(%)b
Conception
Rate
(%)c
Timed-AI
Pregnancy
Rate (%)d
Synchronized
Pregnancy
Rate (%)e
Cloprostenol
250
56.8 (250)
62.0 (142)
43.5 (108)
54.0 (250)
Dinoprost
254
50.8 (254)
62.0 (129)
32.8 (125)
47.6 (254)
= 0.17
> 0.05
= 0.09
= 0.15
Treatments
P-values
a
All cows received GnRH (100 µg) at initiation of the 7 d CIDR treatment, with either Estrumate (500 μg)
or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8-12 h later and
all cows not exhibiting estrus by the third day after PGF2 received GnRH and were timed-AI 72-80 h after
PGF2 injection. Results presented as mean (total).
b
Percentage of cows displaying estrus during the 3 d after PGF2 of the total treated.
c
d
e
Percentage of cows pregnant during the 3 d synchronized breeding of the total treated.
66
Table 2 Estrous, conception and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos
treatments administered at CIDR removal by treatment (TRT), year, and a treatment by year interaction
(TRT*YEAR).a
N
3 d Estrous
Response
(%)b
Conception
Rate
(%)c
Timed-AI
Pregnancy
Rate (%)d
Synchronized
Pregnancy
Rate (%)e
YEAR 1
157
52.9 (157)
77.1 (83)
46.0 (74)
62.4 (157)
Cloprostenol
78
57.7 (78)
82.2 (45)
54.6 (33)
70.5 (78)
Dinoprost
79
48.1 (79)
71.1 (38)
39.0 (41)
54.4 (79)
YEAR 2
178
48.3 (178)
47.7 (86)
37.0 (92)
42.1 (178)
Cloprostenol
88
51.1 (88)
46.7 (45)
44.2 (43)
45.5 (88)
Dinoprost
90
45.6 (90)
48.8 (41)
30.6 (49)
38.9 (90)
YEAR 3
169
60.4 (169)
61.8 (102)
29.9 (67)
49.1 (169)
Cloprostenol
84
61.9 (84)
57.7 (52)
31.3 (32)
47.6 (84)
Dinoprost
85
58.8 (85)
66.0 (50)
28.6 (35)
50.6 (85)
TRT
P = 0.17
P > 0.05
P = 0.09
P = 0.15
YEAR
P = 0.07
P < 0.05
P = 0.14
P < 0.05
TRT*YEAR
> 0.05
> 0.05
> 0.05
> 0.05
Treatments
a
All cows received GnRH (100 µg) at initiation of the 7 d CIDR treatment, with either Estrumate (500 μg)
or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8-12 h later and
all cows not exhibiting estrus by the third day after PGF2 received GnRH and were timed-AI 72-80 h after
PGF2 injection. Results presented as mean (total).
b
c
d
e
67
Table 3 Estrous, conception and pregnancy rates of Bos taurus, Bos indicus, and Bos indicus x Bos
treatments administered at CIDR removal by breed.a
Breed Group
N
3 d Estrous
Response
(%)b
Angus (AN)
106
58.5 (106)
64.5 (62)
34.1 (44)
51.9 (106)
¾ AN ¼ BR
106
51.9 (106)
54.6 (55)
43.1 (51)
49.1 (106)
⅝ AN ⅜ BR
57
63.2 (57)
55.6 (36)
38.1 (21)
49.1 (57)
½ AN ½ BR
135
51.9 (135)
72.9 (70)
44.6 (65)
59.3 (135)
¾ BR ¼ AN
50
44.0 (50)
54.6 (22)
28.6 (28)
40.0 (50)
Brahman (BR)
50
52.0 (50)
57.7 (26)
25.0 (24)
42.0 (50)
> 0.05
> 0.05
> 0.05
= 0.15
P-value
Conception
Rate
(%)c
Timed-AI
Pregnancy
Rate (%)d
Synchronized
Pregnancy
Rate (%)e
a
All cows received GnRH (100 µg) at initiation of the 7 d CIDR treatment, with either Estrumate (500
μg) or Lutalyse (25 mg) at CIDR removal. Cows that exhibited estrus were AI approximately 8-12 h later
and all cows not exhibiting estrus by the third day after PGF2 received GnRH and were timed-AI 72-80 h
after PGF2 injection. Results presented as mean (total).
b
c
d
e
68
Presynchronization of Suckled Beef Cows with Human Chorionic
Gonadotropin (hCG) 7 days prior to Initiation of a Fixed-time Artificial
Insemination Protocol Fails to Enhance Fertility
Guilherme Marquezini1
Carl Dahlen1
G. Cliff Lamb1
Administration of human chorionic gonadotropin 7 d before initiating the CO-Synch + CIDR estrous
synchronization protocol failed to enhance pregnancy rates. When replacing gonadotropin releasing
hormone with human chorionic gonadotropin at the time of insemination, pregnancy rates to fixed-time
artificial insemination may be reduced.
Summary
Two experiments were conducted to evaluate
whether hCG administered 7 d before initiating
the CO-Synch + CIDR estrous synchronization
protocol (Exp. 1 and 2), or replacing
gonadotropin releasing hormone (GnRH) with
human chorionic gonadotropin (hCG) at the
time of insemination (Exp. 1), would alter
pregnancy rate to a fixed-time artificial
insemination (TAI) in suckled beef cows. In
Exp. 1, cows were stratified by days postpartum,
age, and parity and randomly assigned to one of
four treatments: 1) Cows received GnRH at
CIDR insertion (d -7) and 25 mg of
prostaglandin F2 (PG) at CIDR removal (d 0),
followed in 64 to 68 hr by a TAI with second
injection of GnRH at the time of insemination
(CG; n=29); 2) same as CG but the second
injection of GnRH at the time of insemination
was replaced by hCG (CH; n=28); 3) same as
GG, but cows received hCG7 d (d -14) priorto
CIDR insertion (HG; n=29); and 4) sameas GH,
but cows received hCG 7 d (d -14) priorto CIDR
insertion (HH; n=29). Pregnancy rates were
52%, 41%, 59%, and 38% for GG, GH, HG, and
HH, respectively. Cows receiving hCG(39%) in
place of GnRH at TAI tended (P = 0.06) to have
poorer pregnancy rates than those receiving
GnRH (56%). In Exp. 2, cows were stratified
based on days postpartum, body condition score
(BCS), breed type, and calf sex and then
assigned to the CG (n = 102) or HG (n
= 103) treatments. Overall pregnancy rates
were 51%, but no differences in pregnancy rates
were detected between treatments, breed, days
postpartum, or calf sex. We concluded that
presynchronization with hCG 7d prior to
initiation of the CO-Synch + CIDR protocol
failed to enhance pregnancy rates, but replacing
GnRH with hCG at the time of AI may reduce
pregnancy rates.
Introduction
Producers are continually seeking to improve
reproductive efficiency in cattle. One method of
enhancing reproductive efficiency is to utilize
estrous synchronization (ES) and AI. Effective
TAI systems have been developed (Larson et al.,
2006) that reduce the amount of time and labor
associated with estrous synchronization and
TAI. To ensure the greatest response to ES and
AI, increasing the percentage of cows cycling at
the beginning of the breeding season is
paramount.
Therefore,
the
use
of
presynchronization to initiate estrous cycles in
noncycling cows may enhance the response to
the ES and AI protocol. Presynchronization
protocols have been developed to increase the
rate of ovulation by the first administration of
GnRH in a GnRH-PG-GnRH protocol (Busch et
al., 2007). Presynchronization of estrus with 2
injections of PG administered 14 d apart, prior to
initiating a TAI protocol enhanced pregnancy
69
= 103) treatments from Experiment 1 (Figure 1).
Mean BCS was 5.5 and days postpartum was 70
d. Pregnancy was diagnosed by transrectal
ultrasonography on d 29 after TAI.
rates in cows (Moreira et al., 2001; Navanukraw
et al., 2004). The improvement of the response
of the GnRH is believed to be causedby an
increased proportion of cows in early to middiestrus when the first GnRH injection of the
timed
AI protocol was administered,
(Vasconcelos et al., 1999; Moreira et al., 2000).
The use of hCG induces potent LH activity on
ovarian cells, which can even lead to ovulation
throughout the estrous cycle.
Results
Experiment 1.
Incidence of cycling, concentrations of
progesterone, and pregnancy rates did not differ
among the four treatments, but when evaluated
as a 2 x 2 factorial differences were detected.
Cows receiving no pretreatment (control) or
hCG on d -14 are illustrated in Table 1, whereas
comparisons between cows treated with GnRH
or hCG at TAI (d 3) are illustrated in Table 2.
Overall, 55% of cows were cycling by d -14 and
did not differ between treatments; however, the
percentage of cycling cows tended (P = 0.10) to
increase by d -7 after receiving hCG (78.9%)
compared to untreated controls (64.9%).
Subsequently,
the
concentrations
of
progesterone (P4) tended (P = 0.13) to be
greater at the time of CIDR insertion (d -7) in
cows receiving hCG compared to untreated
controls. The enhanced incidence of more cows
with a corpus luteum on d -7 did not appear to
enhance fertility. Overall pregnancy rates were
47.4% and were not altered by pretreatment with
hCG. However, pregnancy rates tended (P =
0.06) to be reduced in cows receiving hCG at
TAI compared to those receiving GnRH.
Our objectives were: 1) to evaluate whether hCG
administered 7 d before initiating a TAI estrous
synchronization protocol would enhance
pregnancy rates; and 2) whether replacing
GnRH with hCG at the time of insemination
would alter pregnancy rate to TAI.
Experiment 1.
One hundred fifteen cows were stratified by
days postpartum, age, and parity before being
assigned to one of four treatments in a 2 x 2
factorial arrangement (Figure 1): 1) cows
received a 100 µg injection of GnRH (OvaCyst;
IVX Animal Health) and a CIDR containing
1.38 g of progesterone (Pfizer Animal Health)
on d -7 and 25 mg of PG (Lutalyse, dinoprost
tromethamine, Pfizer Animal Health) at CIDR
removal (d 0), followed in 67 hr by a TAI with
second injection of GnRH at the time of
insemination (Control GnRH; CG; n=29); 2)
same as CG but a second injection of GnRH at
the time of insemination was replaced by 1,000
IU of hCG (CH; n=28); 3) same as CG, but
cows received 1,000 IU of hCG administered 7 d
(d-14) before CIDR insertion (HG; n=29); and
4) same as CH, but cows received 1,000 IU of
hCG on d -14 (HH; n=29). Blood samples were
collected on d -24, -14,-7, 0, 3, 10 and 16 to
harvest serum for analysis of concentration of
progesterone. Progesterone concentration was
used to determine cycling status. Pregnancy was
diagnosed by transrectal ultrasonography 31 d
after TAI.
We conclude that hCG appeared to influence the
percentage of cows with a corpus luteum on d -7
but failed to enhance fertility when administered
7 d prior to initiation of ES. In addition,
replacing GnRH with hCG at TAI appeared to
suppress pregnancy rates.
Experiment 2.
Overall pregnancy rates were 51% and did not
differ among treatments. In addition, breed, sex
of offspring, days postpartum, and parity did not
appear to influence pregnancy rates (Table 3).
Therefore, we conclude that presynchronization
with hCG 7 d prior to initiating the CO-Synch +
CIDR protocol, did not enhance pregnancy rates.
Experiment 2.
Two hundred and five cows were stratified
based on days postpartum, BCS, breed type
(British or Crossbreed), and calf sex (male or
female) and assigned to CG (n= 102) and HG (n
70
Acknowledgements
We thank Pfizer Animal Health (New York, NY) for contributions of prostaglandin F2 (Lutalyse) and
CIDR inserts and IVX Animal Health (St. Joseph, MO) for donation of gonadotropin-releasing hormone
(OvaCyst). Appreciation also is expressed to S. Bird, R. Irurtia, A. Martins, Jr., Olivia Helms, Don
Jones, Mary Maddox, Todd Matthews, Harvey Standland, and David Thomas for their assistance with
data collection and laboratory analysis.
LITERATURE CITED
Busch et al. 2007. J. Anim. Sci. 85: 1933.
Larson et al. 2006. J. Anim. Sci. 84:332.
Moreira et al. 2001. J. Dairy Sci. 84:1646.
Moreira et al. 2000. J. Anim. Sci. 78:1568.
Navanukraw et al. 2004. J. Dairy Sci. 87:1551.
Vasconcelos et al. 1999. Theriogenology 52:1067.
1
Guilherme Marquezini, Graduate Student, UF/IFAS, NFREC, Marianna, FL; Carl Dahlen, Graduate
Student, University of Minnesota, NWROC, Crookston, MN; G. Cliff Lamb, Associate Professor,
UF/IFAS, NFREC, Marianna, FL
71
Figure 1. Schematic of experimental design for cows treated with PG, CIDR, and GnRH or hCG in
Exp. 1 (CG, CH, HG, and HH) and Exp. 2 (CG and HG).
72
Table 1. Concentrations of progesterone (P4), percentage of cycling, and pregnancy rates in
cows receiving either control or hCG treatment on d -14 (Exp. 1).
Treatment on d -14a
Item
Control (CG and CH)
hCG (HG and HH)
----------ng/ml---------P4 on d -14, ng/ml
1.6 ± 0.2
1.5 ± 0.2
P4 on d -7, ng/ml
1.9 ± 0.4
2.7 ± 0.4
P4 on d 0, ng/ml
2.5 ± 0.3
3.1 ± 0.3
----------no./no. (%)---------Cycling cows on d -14b
31/57 (54.4)
32/57 (56.1)
Cycling cows on d -7 c
37/57 (64.9)w
45/57 (78.9)x
Cows with >1 ng/ml P4 on d -14d
26/57 (45.6)
27/57 (47.4)
Cows with >1 ng/ml P4 on d -7d
23/57 (40.4)y
36/57 (63.2)z
Pregnancy rates
26/57 (45.6)
28/57 (49.1)
a
Cows were assigned to receive no treatment or hCG on d -14.
Number and percentage of cows cycling on d -14 based on two blood samples taken on d d -25
and -14.
c
Number and percentage of cows cycling on d -7 based on three blood samples taken on d d -25, 14, and -7.
d
Cows with concentrations of P4 >1 ng/ml on d-14 or -7.
w,x
Percentages differ (P = 0.10).
y,z
Percentages differ (P < 0.05).
b
73
Table 2. Concentrations of progesterone (P4) and pregnancy rates in cows receiving either
GnRH or hCGat TAI on d 3 (Exp. 1).
Treatment on d 3a
Item
GnRH (CG and HG)
hCG (CH and HH)
----------ng/ml---------P4 on d 3, ng/ml
0.1 ± 0.2
0.2 ± 0.2
P4 on d 10, ng/ml
2.4 ± 0.2
2.3 ± 0.2
P4 on d 16, ng/ml
3.4 ± 0.3
3.4 ± 0.3
P4 on d 29, ng/ml
2.8 ± 0.4
2.6 ± 0.4
----------no./no. (%)---------Pregnancy rates
a
32/57 (56.1)x
22/57 (38.6)y
Cows were assigned to receive GnRH or hCG on d 3 (at the time of TAI).
Percentages differ (P = 0.06).
x,y
74
Table 3. Pregnancy rates of cows assigned to receive control or hCG treatment on d -14 (Exp.2).
Treatmentsa
Item
CG
HG
----------no./no. (%)----------
Breed
Bos taurus
16/37 (43.2)
24/45 (53.3)
Bos indicus crossbred
35/63 (55.6)
26/55 (47.3)
Female
22/43 (51.1)
22/42 (52.4)
Male
28/55 (50.9)
24/53 (45.3)
<60 d
12/25 (48.0)
11/27 (40.7)
>60 d
40/76 (52.6)
39/74 (52.7)
Primiparous
10/20 (50.0)
9/25 (36.0)
Multiparous
42/81 (51.9)
41/76 (53.9)
Calf sex
Days postpartum
Parity
a
Cows were assigned to receive no treatment or hCG on d -14.
75
76
Effect of Optaflexx® 45 (Ractopamine-HCl) on Live and Carcass Performance
when Fed to Steers During the Final 28 Days of Feeding
John Michael Gonzalez1
Dwain Johnson
Todd Thrift
Jesse Savell
Supplementation with 200 mg•hd-1•d-1of Optaflexx® 45 (Ractopamine-HCl) to steers during the final 28
d of feeding prior to harvest did not affect live performance and minimally affected carcass
characteristics. In addition, Optaflexx® did not affect muscle weights, dimensions or tenderness of four
muscles of beef cattle.
Summary
The goal of this study was to evaluate the effects
of Optaflexx® supplementation to steers during
the final 28 d of feeding on live and carcass
performance. Thirty-four steers were separated
into four harvest groups and fed at the
University of Florida Beef Teaching Unit.
Within each harvest group, the steers were
separated into two pens. Both pens were fed a
control diet of 85% corn, 7.5% cottonseed hulls,
and 7.5% commercially produced protein pellet.
When pens were visually 28 d from reaching a
pen average of 0.4 inch of backfat, pens were
supplemented with a top dress that contained 0
and 200 mg•hd-1•d-1of Optaflexx®. After d 28 of
supplementation for each harvest group, steers
were transported to the University of Florida
Meats Laboratory and harvested under Federal
inspection. A University employee collected
carcass data 48 h postmortem. 72 h postmortem,
the strip loin and top round were removed from
the right side of each carcass.
The
Semimembranosus, Adductor, and Gracilis were
separated from the top round and the
Longissimus dorsi was separated from the strip
loin. Commodity weight, denuded weight, and
muscle dimensions were collected on all muscles
of interest. Whole denuded muscles were then
vacuum packaged, wet aged until d 13
postmortem, and cut into 1 inch steaks for
tenderness evaluation by Warner-Bratzler shear
force. The inclusion of Optaflexx® during the
final 28 d of feeding did not have an effect (P >
0.05) on live performance characteristics. In
addition, most carcass characteristics were
unaffected (P > 0.05) by supplementation except
dressing percentage (P < 0.20), lean maturity (P
< 0.05), marbling score (P < 0.05), and muscle
firmness (P < 0.20). The muscle weights
and dimensions of the adductor and
semimembranosus were unaffected (P > 0.05)
by Optaflexx® supplementation. Only the width
and minimum depth of the longissimus dorsi and
gracilis were improved by Optaflexx®. Finally,
tenderness of steaks from all four muscles as
evaluated by Warner-Bratzler shear force was
unaffected by Optaflexx®.
Introduction
The supplement Optaflexx® 45 (RactopamineHydrochloride) belongs to a class of compounds
called beta-adrenergic agonists. Beta-adrenergic
agonists increase skeletal muscle accretion by
redirecting dietary nutrients away from adipose
tissue accretion to skeletal muscle growth.
Because of this, these compounds are classified
as “repartiontiong agents” (Mersmann, 1979).
Currently, the FDA approves the use of
ractopamine in both swine (Paylean® in 1999)
77
and cattle (Optaflexx® in 2003). The FDA
approves the use of Optaflexx® for cattle fed in
confinement during the last 24 to 42 d of feeding
before slaughter. Since Elanco Animal Health
commercially introduced Optaflexx® in 2004, an
increase in the number of studies published
evaluating the effects of Optaflexx® on beef
cattle indicates a renewed interest in research
evaluating the effects of beta-adrenergic agonists
on live performance and carcass quality.
Numerous studies with swine and emerging data
with cattle indicate ractopamine elicits positive
effects on both live and carcass performance
parameters.
separated into four harvest groups based on time
till the cattle will reach a harvest endpoint of 0.4
inch of backfat. All cattle followed the same
implantation program consisting of a Ralgro
(Intervet, Millsbooro, DE) implant followed by a
Revalor-S (Intervet, Millsbooro, DE) implant.
Within each harvest group, steers were stratified
by weight and visual backfat thickness into two
pens. Steers were fed daily at 6 p.m. in concrete
bunks that provided 2.25 feet per head of bunk
space. Steers were fed a concentrate diet
consisting of 85% corn, 7.5% cottonseed hulls,
and 7.5% commercially produced protein pellet.
When pens were visually 28 d from reaching a
pen average of 0.4 inch of backfat, pens were
supplemented with a top dress that contained 0
and 200 mg•hd-1•d-1of Optaflexx® (Elanco,
Greenfield, IN). Approximately two wk before
the beginning of the 28 d Optaflexx®
supplementation period, both the control and
treatment pens were top dressed with a blank top
dress at a rate of 1 lb•hd- 1•d-1 to allow the steers
time to adjust to the top dress. Once the
supplementation period began, the control pen
continued to receive the blank top dress at a rate
of 2 lb•hd- 1•d-1. The treatment pens received 2
lb•hd- 1•d-1 of top dress designed to provide 200
mg•hd-1•d-1 of Optaflexx®. All top dressings
were hand mixed into the ration daily.
Beta-adrenergic agonists, including ractopamine,
commonly improve live performance by
increasing average daily gain, average daily feed
intake, and feed to gain ratio. In addition to the
live performance benefits, at the carcass level,
ractopamine can increase hot carcass weight and
ribeye area, decrease fat, and increase dressing
percentage by as much as 3.6% (Schroeder et al.,
2005; Winterholler et al., 2007). While a
majority of the published data on ractopamine
documents its effects on whole carcass
parameters, little data exists on yields from
muscles throughout the carcass. Currently, the
only data published indicates that another betaagonist, zilpaterol, increased the percentages of
the knuckle, skirt, neck, and inside round in
cattle (Plascencia et al., 1999). Optaflexx® may
have the ability to also increase yields from
individual muscles of supplemented carcasses.
In today‟s market conditions of high corn and
feed prices, the use of ractopamine to improve
average daily gain, gain to feed ratio, and
carcass characteristics becomes an attractive
option for producers as a means to lower the cost
of beef production. Therefore, the objective of
our study was to further investigate the
effectiveness of Optaflexx® on traditional live
and carcass performance, while also evaluating
its effect on whole muscle yields from the
carcass.
Carcass and Muscle Data Collection
On d 28 of supplementation, steers were
transported to the University of Florida Meats
Laboratory for harvesting.
Steers were
harvested in a common USDA federally
inspected manner. During harvesting, weights of
the head, pluck, viscera, feet, and hide were
collected. Following a 48 h chill period,
carcasses were ribbed and an experienced
university employee collected carcass data.
Seventy-two h postmortem, the bone-in strip
loin and top round were excised from the right
side of each carcass. The Longissimus dorsi
muscle was separated from the bone-in strip
loin.
Similarly,
the
Semimembranosus,
Adductor, and Gracilis were separated from the
top round. After separation, each muscle was
trimmed to one tenth of an inch of fat and the
commodity weight was taken. Muscles were
then trimmed of all visible fat and epimysium
connective tissue, and a denuded weight was
Animals and Dietary Treatments
Thirty-four steers were selected from steers
housed at the University of Florida Beef
Teaching Unit. Upon selection, steers were
78
feed ration due to Optaflexx® supplementation.
They also reported that Optaflexx® can
significantly improve total gain by 6 %. Live
performance data are presented in Table 1. At
the beginning of the 28 d supplementation
period, both treatment groups‟ body weights
were not significantly different (P > 0.05).
During the 28 d supplementation period both
treatment groups had similar (P > 0.05) dry
matter intake (DMI), and at the end of the trial
period body, weights for both treatment groups
were not significantly different (P > 0.05). Data
from this study does not agree with most of the
published data because all live performance
variables measured were not significantly (P >
0.05) improved by the inclusion of Optaflexx®
in the diet. However, ADG and gain to feed
ratio (G:F) were increased numerically by 10
and 7%, respectively. Overall gain data is the
most encouraging data from the live
performance data. Published studies indicate
that Optaflexx® can increase gain significantly
by 6%, while in the current study; gain was
increased by 9%.
taken. Finally, using a measuring tape, muscle
length, width, maximum depth, and minimum
depth measurements were taken on each muscle.
Following the collection of muscle dimension
data, muscles were vacuum packaged and stored
at 35 ± 3°F until 13 d postmortem.
On d 13 postmortem, one inch steaks were cut
from the center of each muscle perpendicular to
the orientation of the muscle fibers for WarnerBratzler shear force analysis. Steaks were once
again vacuum packaged and stored at -40°F until
Warner-Bratzler shear force analysis could be
conducted. When ready for analysis, steaks
were thawed at 37 ± 3°F for 24 h, and cooked on
Hamilton Beach open top grills to an internal
temperature of 160°F. Steaks were turned once
at 80°F. Cooked steaks were then chilled at 37
± 3°F for 24 h. Once chilled, six one-half inch
cores were obtained from each steak parallel to
the orientation of the muscle fibers. Each core
was sheared once through the center using an
Instron Universal Testing Machine with a
Warner-Bratzler head.
Statistics
Live performance and carcass data was analyzed
as a randomized complete block design with
harvest group as the blocking factor and
treatment as the fixed effect. All measured
variables were analyzed with the PROC MIXED
procedure of SAS (SAS Inst. Inc., Carry, NC,
2002). Muscle data was analyzed as a split-plot
design with treatment considered the whole plot
and muscle considered the sub-plot. Pair-wise
comparisons between the least square means of
the factor levels were computed by using the
PDIFF option of the LSMEANS statement.
Differences were considered significant at an
alpha = 0.05 and tendencies at an alpha = 0.15.
Carcass Performance
Inedible offal weights and carcass data are
presented in Table 1.
The weights and
percentage of total body weight of the head,
pluck, viscera, feet, and hide were not
significantly (P > 0.05) affected by the inclusion
of Optaflexx® in the diet. Important carcass
measurements that indicate increased muscling,
including hot carcass weight, longissimus
muscle area, and longissimus muscle area per
100 pounds were unaffected (P > 0.05) by
Optaflexx® supplementation.
This could
indicate that Optaflexx® fed at 200 mg•hd-1•d-1
does not effectively increase muscling when fed
in this manner. However, Optaflexx® tended (P
< 0.15) to increase dressing percentage which
could be beneficial to a producer. Carcass lean
quality parameters including color and texture
scores were unaffected (P > 0.05) by Optaflexx®
supplementation. Lean maturity of Optaflexx®
supplemented animals appeared (P < 0.05)
physiologically older, but these values were still
within the A maturity range. Optaflexx® also
tended (P < 0.15) to soften the firmness of the
lean of supplemented animals.
Results
Live Performance
As mentioned earlier, because numerous reports
indicate that Optaflexx® increases average daily
gain, ADG gain to feed ratio, and overall gain, a
producer may use Optaflexx® in their feeding
program to keep the costs of gain down.
Winterholler
et
al.
(2007)
reported
improvements in average daily gain and gain to
79
When feeding Optaflexx® to the cattle,
producers are often concerned about is its effect
on fat deposition, specifically marbling.
Marbling score was significantly (P < 0.05)
affected by Optaflexx® supplementation.
Concern about this effect should be minimal
since supplemented steers were still in the same
„Slight‟ category as the non-supplemented steers
and quality grade was unaffected (P > 0.05).
Other carcass fat measurements, namely 12th rib
fat thickness and kidney heart and pelvic fat,
were not affected (P > 0.05) by Optaflexx®
supplementation. Therefore, this resulted in
both treatment groups having similar (P > 0.05)
yield grades.
Optaflexx® increases muscling often causes
problems with meat tenderness. In the current
study, Optaflexx® did not significantly (P >
0.05) affect any of the muscles observed. All
muscles, regardless of treatment group, were
considered acceptable tender when analyzed by
Warner-Bratzler shear force.
Data from the current study indicates that
feeding Optaflexx® at 200 mg•hd-1•d-1 for the
final 28 d before slaughter has little or no effect
on live, carcass, and individual muscle
performance. While some of the live gain data
was promising, a producer should consider
employing a different feeding strategy (greater
dosage or feeding time) than the one followed in
this study to elicit more beneficial effects from
feeding Optaflexx®.
Commodity weights, denuded weights, muscle
dimensions, and Warner-Bratzler shear force
values are presented in Table 2. Muscle weights
and dimensions were measured with the hope of
demonstrating the ability of Optaflexx® to
improve muscling of steers.
However,
®
Optaflexx did not significantly (P > 0.05)
affect the muscle weights or dimensions of most
of the muscles analyzed.
Optaflexx® did
significantly (P < 0.05) increase the width of the
Gracilis, and tended (P < 0.15) to increase the
width of the Longissimus dorsi. Optaflexx® also
tended (P < 0.15) to increase the minimum
depth of the Gracilis. These findings indicate
that Optaflexx® has a limited ability to increase
muscling in the muscles of the top round and
strip loin. The mechanism with which
Literature Cited
Mersmann, Harry J. 1998. J. Anim. Sci. 76:160-172.
Plascencia et al. 1999. Proceedings, Western Section, American Society of Animal
Science. 50:331-334.
Schroeder et al. 2005. J Anim. Sci. 83(Suppl. 1):111(Abstr.).
Winterholler et al. 2007. J. Anim. Sci. 85:413-419.
1
John Michael Gonzalez, Graduate Student; Dwain Johnson, Professor; Todd Thrift, Associate
Professor; Jesse Savell, UF-IFAS, Animal Sciences, Gainesville, FL
80
Table 1. Live, offal, and carcass performance of steers supplemented with and without
Optaflexx®
Item
Control
Ractopamine, 200 mg•hd-1•d-1
Live Performance
Initial BW, lb
1,171
1,152
Final BW, lb
1,244
1,231
DMI, lb/pen/d
86.29
87.50
Gain, lb
72.05
78.53
ADG, lb/d
2.65
2.89
G:F
0.128
0.138
Offal Weights
Head, lb
30.82
31.20
Head Percentage1
2.49
2.53
Feet, lb
22.80
22.88
Feet Percentage1
1.84
1.86
Pluck, lb
16.73
16.36
Pluck Percentage1
1.35
1.33
Empty Rumen, lb
124.05
121.36
Empty Rumen
9.94
9.85
Percentage1
Hide, lb
92.18
92.24
1
Hide Percentage
7.42
7.52
Carcass Performance
HCW, lb
758.59
761.59
Dressing Percent2
60.92x
61.86y
3
a
Lean Maturity
145.29
156.47b
3
Bone Maturity
150.79
148.44
4
a
Marbling Score
335.88
324.12b
5
Color Score
3.20
3.48
Texture Score6
3.36
3.53
Firmness Score7
2.06x
2.47y
12th rib fat, in
0.92
0.93
LM area, in2
13.18
13.54
KPH
2.17
2.28
Yield Grade
2.61
2.60
Quality Grade9
16.35
16.11
a-b
Means within a row without common superscript significantly differ (P < 0.05).
SEM
22.75
23.66
5.47
5.07
0.20
0.01
0.97
0.06
0.57
0.04
0.57
0.04
6.00
0.43
3.48
0.28
16.69
0.98
3.96
5.93
4.40
0.25
0.23
0.20
0.14
0.51
0.10
0.19
0.35
x-y
Means within a row without common superscript tend to differ (P < 0.15).
1
Percentage of live weight.
2
Dressing Percentage = (HCW/ Final BW)* 100.
3
100 = A; 200 = B; 300 = C; 400 = D; 500 = E.
4
100 Practically Devoid; 200 = Traces; 300 = Slight; 400 = Small.
5
1 = Bright Cherry Red; 8 = Extremely Dark Red.
6
1 = Very Fine; 7 = Extremely Course.
7
1 = Very Firm; 7 = Extremely Soft.
9
13-15 = Standard; 16-18 Select; 19-21 Choice; 22-24 Prime.
81
Table 2. Muscle weights, dimensions and Warner-Bratzler shear force values from four muscles of cattle fed
with and without Optaflexx®
Item
Adductor
CON1
3.88
0.51
3.46
0.46
8.37
5.85
0.84
Gracilis
RAC1
3.68
0.49
3.31
0.44
8.20
5.71
0.78
Longissimus
dorsi
CON
RAC
13.07
12.76
1.73
1.68
8.69
9.08
1.14
1.19
15.70
15.48
6.31x
6.73y
1.20
1.23
CON
RAC
Commodity, lb
4.74
4.98
Percent HCW2
0.62
0.65
Denuded, lb
2.33
2.36
2
Percent HCW
0.31
0.31
Length, in
12.68
12.34
Width, in
7.14a
7.69b
x
Minimum Depth, in
0.50
0.62y
Maximum Depth,
3.61
3.55
1.16
1.18
2.46
2.52
in
3
WBS , lb
7.17
7.72
8.33
7.30
7.69
7.08
a-b
Means within a row without common superscript significantly differ (P < 0.05).
Semimembranosus
SEM
CON
12.24
1.61
10.98
1.44
13.42
7.85
0.80
RAC
12.19
1.60
10.96
1.43
13.55
7.59
0.85
0.42
0.04
0.26
0.02
0.31
0.17
0.17
4.59
4.64
0.07
9.13
8.47
0.55
x-y
Means within a row without common superscript tend to differ (P < 0.15).
1
CON = control treatment; RAC = Ractopamine treatment.
2
Muscle weight percentage of hot carcass weight.
3
Warner-Bratzler shear force values.
82
Evaluation of Whole, In-shell Peanuts as a Supplement Feed for Beef Cows
Bob Myer1
Gary Hill
Gary Hansen
Dan Gorbet
Results indicated that raw, whole in-shell peanuts may have potential as an energy and protein
supplement feed for mature beef cows.
Summary
A cow feeding trial and a digestion trial were
conducted to evaluate the suitability of using
whole, in-shell raw peanuts (WP) as an energy
and protein supplement feed for beef cattle. The
digestion trial utilized 18 growing beef steers
(584 lb avg. initial wt.). The steers were fed
bermudagrass free choice plus one of three
supplement treatments: 1) corn and cottonseed
meal mix (50:50; CCSM; control), 2) corn and
WP mix (50:50; CWP), or 3) WP. Hay and diet
dry matter (DM) consumption, and apparent
digestibility of DM, acid detergent fiber (ADF),
and neutral detergent fiber NDF were slightly
reduced (P<0.05) for steers on the WP
treatment compared to CCSM and CWP
treatments; CCSM and CWP were similar.
Digestibility of crude protein (CP) of WP
treatment was similar to CCSM. The cow
feeding trial utilized 80 mature late gestating
cows (1,210 lb avg. initial wt.). The cows were
fed bermudagrass hay free choice and fed either
CCSM (50:50) or WP as a supplement feed 3x
weekly that provided an average of 2.5 lb/d per
head. Supplement treatment did not affect cow
body condition (BCS), but body weight (BW)
gain over the 84 d trials tended to be lower for
WP vs. CCSM supplement treatment (P=0.09).
Subsequent calf birth wt, survival rate and
weaning wt, and subsequent cow AI conception
rate were not affected by supplement treatment.
Results indicate that WP may be a suitable, easy
to feed energy and protein supplement for
wintering mature beef cows; however, as noted
from the steer digestibility trial, some decrease
in total diet digestibility may occur.
Introduction
Peanut (Arachis hypogaea L.) is a legume crop
commonly grown in the southeastern USA for
pod/seed production for human consumption.
Changes in the U.S. peanut program have
resulted in decreased peanut prices. Those
peanuts not suitable for human consumption (i.e.
“oil stock” peanuts) may offer a convenient,
easy to use energy and protein supplement for
beef cattle when fed whole. These peanuts,
which are about 10 to 20% shell by weight,
contain about 20% CP, 40% fat (oil) and 6%
moisture. Previous research with other intact
whole oil seeds, such as sunflower seeds (Banta
et al., 2006), raw soybeans (Long et al., 2008)
and whole cottonseed (Hill et al., 2008) have
shown these oilseeds to be a simple, convenient
way to provide supplemental energy and protein
for beef cattle (Funston, 2004). The high oil
content of raw, whole in-shell peanuts would be
an effective way to increase diet energy density.
We are not aware of any published reports on
using whole in-shell peanuts in beef cattle
feeding, but field observations have noted that
mature beef cattle will consume in-shell peanuts.
Thus, our objective was to evaluate raw whole,
in-shell peanuts as a supplement feed for beef
83
cattle, in particular as a supplement feed for
mature beef cows.
were then computed for DM, CP, ADF and
NDF. Individual steer DMI was computed as
the difference between daily feed intake and
refusals.
Procedures
Two experiments were conducted – a
digestibility trial conducted at the University of
Georgia, CPES Tifton located in south central
Georgia, and a beef cow feeding trial conducted
at the University of Florida, NFREC Marianna
located in northwest Florida. Both trials were
conducted in accordance with approvals of both
universities animal use committees.
Beef cow trial
The cow feeding trial was a comparison of two
supplement treatments: CCSM (50:50; control)
and WP fed to mature, wintering beef cows fed
grass hay. Trial was conducted during the 20042005 and 2005-2006 winter seasons. For each
year, 40 mature beef cows (primarily Angus and
Brangus), were divided into two blocks of 20
cows each based on body condition: a low BCS
(avg. = 4.8) and a high BCS (avg. = 5.9) block.
The cows averaged 1,158 ± 145 lb for the first
year and 1,262 ± 145 kg for the second yr, and
were 3 to 11 yr of age. Within the low and high
blocks, the cows were further divided into
treatment groups based on BW, age and genetic
background, which resulted in four groups of 10
cows per yr (two groups of ten of low BCS and
two groups of ten of high BCS cows per
treatment per year). The cattle were divided into
low and high BCS groups to better target
nutritional needs of the cows. Within yr and
within BSC group (block), supplement treatment
was assigned at random.
The assignment
process was repeated for the second yr, thus,
cows had an equal chance of being assigned to
another treatment the second yr. The high BCS
groups were fed 2 lb/d of supplement per head
and the low groups, 3 lb/d per head. The
supplements were fed three times weekly –
Monday, Wednesday and Friday mornings
(0730 to 0830 h). All cows received hay
(„Tifton 85‟ bermudagrass) and a cattle mineral
supplement free choice.
The cows were
maintained as four groups of ten on four 3.2 ac
dormant warm season bahiagrass pastures. The
cows had free access to water and shade.
Although hay was provided, the cows had access
to dormant bahiagrass. Ample feed bunk space
was provided such that all cows in a group were
able to consume supplement at one time. For
each year, the trial lasted for 84 d from midNovember to early February.
Digestion trial
The digestion trial utilized 18 growing beef
steers (avg. initial weight of 584 ± 26 lb; 9 mo.
of age) of Angus, Angus cross, or Polled
Hereford breeding. The steers were randomly
assigned to three supplement treatments (six per
treatment). The supplement treatments were: 1)
corn and cottonseed meal mix (50:50; CCSM;
control), 2) corn and whole peanuts (50:50;
CWP), and 3) whole peanuts (WP).
All
supplements were fed at 3 lb/head/d.
Bermudagrass hay („Tifton 85‟) was fed freechoice, and steers had free-choice access to both
water and a mineral supplement.
The whole peanuts were processed (ground)
before feeding using a hammer mill. The
peanuts were only ground to the extent of
breaking shells, leaving approximately 95% of
the peanut kernels unbroken. Processing was
done to insure intake of the peanuts by the
growing steers. Previous experience at the Tifton
station has noted that growing cattle will not
readily consume whole peanuts. This is contrary
to anecdotal evidence that suggests that mature
cattle will readily consume whole peanuts.
The steers were fed treatment supplements once
daily at 0800 hr. Digestibility was determined
using chromic oxide. Chromic oxide (10 g/steer
daily) was fed with supplements from d 8 to d
17. Fecal samples (12/steer) were collected 3
times daily from d 14 to d 18. Individual steer
fecal samples were dried, ground (1 mm), and
composited over time for each steer. Samples of
hay, corn, peanuts, and fecal samples were
chemically analyzed for DM, CP, ADF and
NDF, and fecal samples were additionally
analyzed for Cr. Apparent digestion coefficients
Individual cow BW and BCS were determined at
the start and end, and every 28 d during the
trials. Weights were determined after a 16 hr
84
In the steer digestion trial, the dietary
supplements were formulated to mimic expected
usage of the raw, whole, in-shell peanuts as a
supplement feed for beef cattle. The CWP
treatment was a simple 50:50 mixture which
may be a logical choice for some producers.
Dietary CP intake varied because of the varied
CP of the supplements (total diet CP, including
hay, was 17.8, 13.1 and 15.4% for the CCSM,
CWP, and WP treatments, respectively). All
diet CP levels exceed NRC (2000)
recommended levels of CP for growing beef
steers. Hay used in the digestibility trial would
be considered good quality based on analyses
(Table 1).
withdrawal from feed and water.
Body
condition scores (1 through 9; 1 = emaciated, 9
obese) were assigned by the same two
individuals throughout the trials.
The peanuts used in the cow trial were “oil
stock” peanuts obtained from the peanut
breeding program at NFREC Marianna. The
bermudagrass hay was grown and harvested at
the center. Representative samples of the
peanuts and hay used were analyzed for nutrient
composition by a commercial feed analysis
laboratory.
Subsequent calf data were collected which
included birth wt, weaning wt and adjusted 210
d calf weaning wt. Calving was from early
February to mid-April each year. All calves
were weaned in early September.
Hay DMI and total diet DMI were reduced
(P<0.02) for steers receiving the WP supplement
compared with the CCSM and CWP treatments
(Table 3). Apparent digestibility coefficients
obtained were relatively high, about 10% higher
than anticipated. Differences due to supplement
treatment were noted. Apparent digestibility of
DM, ADF and NDF were reduced (P<0.01;
Table 3) from steers on the WP treatment
compared to the CCSM and CWP treatments.
The lower intake and digestibility‟s may be the
result of the peanut hulls and (or) relatively high
fat (oil) concentration of the WP. Peanut hulls
are high in fiber and lignin, and are poorly
utilized by beef cattle (Hill, 2002). However,
the hulls would only comprise about 5% of the
total diet. On the other hand, the estimated ether
extract (fat) level of the total diet (WP + hay)
was 13% (DM basis). The estimated ether
extract level of the CWP diet was 7%, just above
the level (6 %) above which interference with
fiber digestion and DM intake can be expected
(Moore et al., 1986; Coppock and Wilks, 1991;
Funston, 2004). In spite of the estimated 7% fat
level, digestibility of DM, ADF and NDF of the
CWP treatment were similar (P>0.10) to those
of the control (CCSM).
Statistical
The steer intake and apparent digestibility data
were statistically analyzed using Proc MIXED
(SAS, 2002). Steer DMI and apparent digestion
coefficients for DM, CP, ADF and NDF were
analyzed as a completely random design, since
steers were individually fed supplement
treatments. Steer DMI and apparent digestion
data were adjusted for initial BW as a covariate.
Data collected from the cow trial included cow
body wt and BCS changes, and subsequent calf
performance. Since the cows were group fed,
the experimental unit was the group of ten cows.
The data were analyzed as a RCB using Proc
MIXED (SAS, 2002) with treatment as fixed
and year as a random effect; BCS group was
treated as a block.
Results
The nutritional analysis of the raw whole, inshell peanuts indicated that peanuts can be a
good source of energy and protein when used as
a supplement feed for beef cattle (Tables 1 and
2). For example, when fed at 2 lb/d per head
along with medium quality grass hay (~ 54%
TDN, 8% CP), the resulting total daily diet for a
1,200 lb beef cow would be about 58% TDN
and 9% CP, more than adequate for a mature
gestating beef cow in good body condition
(NRC, 2000).
In the mature beef cow trial, the feeding of WP
did not (P>0.10) influence BCS at the end of the
84 d feeding phases during late gestation when
compared to control CCSM supplement
treatment (Table 4). Cow body wt gain,
however, tended to be lower for WP vs. CCSM
(P = 0.09; Table 4). Subsequent calf birth wt,
85
calf wt gain and weaning wt were not affected
(P>0.10) by supplement treatment. Subsequent
AI conception rate was not affected by
treatment, however, only a total of 40 cows were
used per treatment.
Results indicated that whole in-shell peanuts can
be a suitable feed supplement for mature beef
cows. These peanuts were readily consumed by
the mature cows. However, it took nearly all
day for the peanuts to be consumed. As noted in
the steer digestibility trial, some decrease in
DMI and total diet digestibility may occur if WP
is fed to cows. The slightly lowered weight gain
noted for the WP treatment in the cow trial may
be a reflection of these effects. Banta et al.
(2006) also noted some decrease in cow weight
change upon interval feeding of whole
sunflower seeds which contain about 40% fat
(oil) that were fed at 3.6 lb/d per head.
Implications
Results indicated that raw, whole in-shell
peanuts could be an easy to use energy and
protein supplement feed for mature beef cows.
However, poor intakes have been noted with
growing beef cattle (Hill, unpublished results).
Some processing (i.e. coarse grinding) and
blending with another feedstuff (i.e. corn) would
be needed to insure intake by growing cattle.
Also, like any high fat feed, caution should be
taken to insure that total diet fat content is not
excessive (i.e. above 6 to 8%).
86
Literature Cited
Banta et al. 2006. J. Anim. Sci. 84:2410-2417.
Funston R. N. 2004. J. Anim. Sci. 82(E. Suppl.):E154-E161.
Hill, G. M. 2002. Peanut By-products Fed to Cattle. In Alternative Feeds for Beef Cattle. The
Veterinary Clinics of North America: Food Animal Practice, v 18. pp. 295-315.
Hill et al. 2008. Proc. 19th Annual Florida Ruminant Nutrition Symp., Dept. of Animal Sciences,
University of Florida, Gainesville. pp. 98-115.
Long et al. 2008. Prof. Anim. Sci. (in press).
Moore et al. 1986. J. Anim. Sci. 63:1267-1273.
NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. (2000 update). Nat‟l. Acad.
Press, Washington, DC.
SAS. 2002. SAS/C OnlineDOC™, Ver. 8.2. SAS Institute, Inc., Cary, NC.
Acknowlegement
This study was supported by funding from the Florida Peanut Producers Association, and the Florida
and Georgia Peanut Check-Offs. The assistance of Mary Chambliss, Harvey Standland, Don
Jones, Todd Matthews, and Brook Hand is gratefully acknowledged.
1
Bob Myer; Professor, Gary Hansen; former Assistant Professor, Dan Gorbert; Professor
Emeritus, UF-IFAS, North Florida Research and Education Center, Marianna, FL; Gary Hill;
Professor, University of Georgia, Coastal Plain Experiment Station, Tifton, Georgia.
87
Table 1. Composition (%) of supplements and hay fed to steers in the digestion triala.
Item
DM
CCSMb
89
c
CWP
90
WPd
92
Corn
89
e
Hay
92
a
Percent DM basis.
b
Corn and cottonseed meal (50:50 mix).
c
Corn and whole, raw peanuts (50:50 mix).
d
Whole, raw in-shell peanuts.
e
'Tifton 85' bermudagrass.
CP
33
16
23
9
12
ADF
6
15
28
2
39
NDF
9
26
41
10
79
Table 2. Nutritional composition of raw whole, in-shell peanuts and hay used in the mature beef
cow triala.
Whole peanuts
Item
Year 1
Year 2
Year 1
Moisture
4.2
7.1
13.9
Crude protein
23.0
20.6
7.8
Crude fat
45
40
NDc
Crude fiber
22
33
31
ADF
24
26
40
NDF
32
37
72
TDN
121
109
57
Ash
2.8
2.8
5.5
Ca
0.28
0.18
0.32
P
0.36
0.34
0.25
a
Analyses done by a commercial laboratory; values are on an as-fed basis.
b
'Tifton 85' bermudagrass.
c
Not determined.
88
Hayb
Year 2
12.9
7.8
ND
36
46
79
56
6.1
0.34
0.26
Table 3. Dietary intake of hay and apparent digestibility coefficients of total diet (supplement +
hay) for the growing steer digestion trial.
Hay DMI,a
Supplement
lb/d
DM
b
f
CCSM
7.7
86.8h
CWPc
7.9f
85.6h
d
g
WP
6.6
81.6i
SEe
0.31
0.68
a
Dry matter intake.
b
Corn and cottonseed meal (50:50 mix).
c
Corn and whole peanuts (50:50 mix).
d
Whole peanuts.
e
Standard error; n = 6.
f,g
P<0.02.
h,i
P<0.01.
% digestibility
CP
ADF
h
86.7
85.3h
82.7i
84.0h
h
84.9
79.4i
0.77
0.81
NDF
87.2f
86.4f
83.2g
0.81
Table 4. Mean performance parameters of wintering mature gestating beef cows fed hay and
supplement, and effects on subsequent calf crop and cow reproductiona.
Supplement treatment
CCSMb
WPc
SEd
P-value
5.5
5.5
+79
79
542
468
95
68
0.05
0.06
7.9
0.3
12.8
12.3
1.8
6.2
NS
NS
0.09
NS
0.23
0.16
0.18
NS
Item
Body condition scoree:
Start
5.5
End
5.5
Cow body wt. change, lb
+108
Calf birth wt., lb
79
Calf weaning wt., 1b
515
Calf wt. gain, lb
436
Calf survival rate, %
100
f
Cow conception rate , %
70
a
Two year study, 40 cows per yr (10 cows per paddock).
b
Rolled corn-cottonseed meal mix (50:50).
c
Whole peanuts.
d
n = 4.
e
Scores of 1 to 9 with 1 = very thin and 9 = obese.
f
Subsequent breeding via AI.
89
90
Co-product and Rumen Degradable Protein Supplementation of Beef Steers
Fed Bahiagrass Forage
Jacqueline Wahrmund1
Matt Hersom
Growing beef cattle consuming bahiagrass hay require supplemental dietary crude protein to maintain
performance and promote ADG. Supplements of dried distillers grains or soybeans hulls can may be
useful supplements. Additional degradable protein may not be beneficial.
Summary
An experiment was conducted to evaluate the
effects of feeding co-products with Optigen® II
on animal performance and blood metabolites in
growing beef calves. Angus steers were allowed
ad libitum access to bahiagrass hay and were
supplemented for 42 d via Calan gates.
Treatments included 1) dried distillers grains; 2)
dried distillers grains + Optigen; 3) soybean
hulls; 4) soybean hulls + Optigen. Amounts of
dried distillers grains and soybean hulls were
formulated to be isonitrogenous. On d 42, there
were no treatment differences for steer
bodyweight (BW), average daily gain (ADG), or
blood glucose concentrations. Across all days,
steers offered only dried distillers grains had
greater plasma urea nitrogen concentrations
than steers offered soybean hulls. On d 14, 28,
and 42, Optigen-supplemented steers had
greater plasma urea nitrogen concentrations
compared to those that were not. Beef cattle
consuming bahiagrass hay require additional
dietary crude protein to maintain performance
and promote ADG. However, when sources of
natural protein are fed, additional rumen
degradable protein may not be necessary.
performance. Bahiagrass in Florida generally
does not contain enough protein to meet growing
cattle requirements. This makes growing calves
particularly susceptible to protein deficiencies
on low-quality forage-based diets, because they
require high levels of protein to support tissue
growth, are.
Dried distillers grains (DDG) are a co-product of
the corn-derived ethanol fuel industry. As
ethanol fuel production continues to increase in
the United States, DDG will become more
available to cattle producers for animal
consumption. Dried distiller grains are high in
crude protein (CP) but relatively low in rumen
degradable protein (RDP; 31.6% CP, 27.9%
RDP, as a % CP). Soybean hulls (SBH) are
another co-product which are relatively low in
total RDP (12.6% CP, 58% RDP, as a % CP).
For growing cattle a small amount of additional
RDP may optimize performance when added to
co-product supplements. Optigen® II (Opt;
Alltech, Inc., Nicholasville, KY) is a urea
product which has slow-release properties that
should result in N availability from urea that is
better synchronized with the energy availability
provided by forage or supplements. A trial was
conducted to evaluate the use of DDG or SBH
with or without additional RDP to background
growing beef steers.
Introduction
Bahiagrass is the most common type of forage
utilized in Florida (Chambliss and Sollenberger,
1991); however, cattle are not able to consume
enough bahiagrass to meet their nutrient
requirements at certain points of the production
cycle. Therefore, supplementation programs
must be developed to optimize beef cattle
Animals and Diets
Fifty-six Angus steers were blocked by
91
bodyweight (BW; mean = 544 ± 57 lb) and
randomly assigned to one of four treatments and
one of seven pens. Treatments included: 1)
DDG (2.62 lb of DM); 2) DDG+Opt (2.62 lb of
DDG, 0.10 lb Optigen® II); 3) SBH (5.79 lb of
DM); 4) SBH+Opt (5.79 lb of SBH, 0.10 lb
Optigen® II). Basal supplements (DDG and
SBH) were formulated to be isonitrogenous
(0.80 lb CP); the addition of Optigen® II
provided 0.10 lb of supplemental RDP. Steers
were offered basal supplements daily beginning
five d prior to the initiation of the experiment.
Bahiagrass hay was offered in each pen, ad
libitum, as large round bales. Fresh bales were
offered each wk, and each bale was weighed and
core-sampled for analysis of chemical
composition.
Steers were individually
supplemented at approximately 0700 via a Calan
gate system. Approximately 0.13 lb of a
vitamin/mineral supplement was included in the
daily supplements.
Because hay was fed as large round bales within
each pen, mean daily hay dry matter intake
(DMI) was calculated using the NRC (2000)
equation:
SBW = 13.91 * RE0.9116 * EQSBW-0.6837
where:
SBW = shrunk body weight
RE = retained energy
EQSBW = equivalent shrunk body
weight,
assuming a 4% shrink, and that RE is
equal to net energy for gain (NEg).
Statistical analysis.
The experiment was designed as a completely
randomized design, with supplement treatment
as the fixed effect (Littell et al., 2006), steer
within treatment as the random effect and
individual steer was the experimental unit. Data
were analyzed using the Mixed procedure of
SAS v9.1. Means were calculated using least
squares means, and means were separated using
the P-diff option when the overall F-value was
<0.10.
Sampling and Analysis
Steers were fed for 42 d, unshrunk BW were
taken on two consecutive days at the initiation (d
-1, 0) and termination of the trial (d 42, 43).
Interim BW were obtained on d 14 and 28. The
two-d mean of BW was utilized to determine
initial and final BW and to determine ADG.
Blood samples were collected for analysis of
plasma urea nitrogen (PUN) and glucose
concentrations. On each of the sampling dates,
spot urine samples were obtained from steers
and creatinine concentrations were determined.
Creatinine concentrations were used to
determine total daily urine output based on the
principle that cattle excrete 883 µmol of
creatinine •(kg BW0.75)-1•d-1 (Chen et al., 1992).
Bodyweight measurements, blood, and urine
samples were obtained approximately two h
after supplements were offered.
Results
Steer performance and intake.
At the initiation of the trial, steer BW averaged
521 lb (Table 1), with no differences (P=0.97)
among treatments.
No differences were
observed in ADG during any two-wk sampling
period (P>0.14). While the addition of Optigen®
II had no effect on overall ADG (P=0.30), steers
offered SBH gained approximately 0.15 lb/d
more (P=0.05) compared to steers offered DDG.
The changes observed in steer BW from d 0 to
14 were approximately 2.4 times greater
compared to the period between d 14 and 28.
The dramatic decline in ADG between the first
two collection periods was likely due to
compensatory gain observed during the first 14
d. Two wk prior to the initiation of the trial,
steers consumed a restricted diet consisting of
only limited amounts of a grain-based feed with
molasses. The purpose of this diet was to induce
hunger to enhance the steers’ willingness to
learn to use the Calan gates. During the two wk
training period, steer BW gain was minimal,
with some steers losing BW. The ADG of all
Weekly hay samples were collected from each
pen and composited for analysis of chemical
composition.
Hay and supplement total
digestible nutrients (TDN) concentrations were
determined using the equation (Fike et al.,
2002):
%TDN = [(% IVDMD * 0.59) + 32.2] *
organic matter concentration.
92
steers was 0.20 lb/d during the three weeks prior
to d 0. The ADG from d -22 to 14 (restriction
through compensation) was nearly equal to the
BW gains observed through the remainder of the
trial (d 14 – 42) for each treatment, indicating
that the steers likely compensated for the lack of
BW gain during the period of feed restriction.
(P<0.001) gain efficiency, while the addition of
Optigen® II did not (P=0.34). Steers offered
DDG-based supplements had a mean gain
efficiency of 0.10, however, steers offered SBHbased supplements had mean gain efficiency of
0.13. Thus, steers consuming supplements
containing SBH were approximately 25% more
efficient at converting feed to BW compared to
steers offered DDG based supplements. The
differences in gain efficiency were mainly
driven by the differences observed in hay DMI.
Forty-two day estimated mean daily hay DMI
(Table 1) was calculated based on shrunk BW
gain and net energy values of the feedstuffs.
Based on the estimations, co-product type
affected voluntary hay DMI (P<0.001), but not
the addition of Optigen® II (P=0.62). Steers
consuming DDG or DDG+Opt had 62% greater
(P<0.05) estimated daily hay DMI compared to
steers offered SBH or SBH+Opt.
The
differences in estimated mean hay DMI resulted
in 18% greater (P<0.001) total DMI for steers
consuming the DDG supplements compared to
steers receiving SBH. The addition of Optigen®
II had no effect (P=0.52) on total DMI.
Physiological response
As a result of the five-d acclimation period prior
to d 0, differences were observed in initial steer
PUN concentrations (Table 2). Plasma urea
nitrogen concentrations of steers consuming the
SBH and SBH-based supplement treatments
were 45% less (P<0.001) than steers consuming
DDG-based supplement treatments on d 0.
Optigen® II was first included in the
supplements on d 0; therefore, resulting in
greater (P=0.05) initial PUN concentration in
steers offered Optigen. On d 14, the steers
consuming DDG-based supplements continued
to have greater (P<0.001) PUN concentrations
compared to steers consuming SBH-based
supplements. Additionally, the inclusion of
Optigen® II increased steer PUN concentrations
by 31% (P<0.001) when included in
supplements containing DDG and by 84% in
supplements containing SBH (P<0.001). On d
28, the inclusion of Optigen® II increased steer
PUN concentrations by 28.2% in DDG
supplements and by 38.0% in SBH supplements
(P<0.001) compared to steers not offered
Optigen® II.
Steers consuming DDG+Opt
maintained the greatest PUN concentrations, and
steers offered only SBH had the lowest PUN
concentrations.
On d 42, steer PUN
concentrations were greatest (P<0.001) in steers
offered DDG+Opt, followed by the steers on the
DDG and SBH+Opt treatments, which were not
different (P>0.10), followed by SBHsupplemented steers.
The decreased DMI observed for steers
consuming the SBH treatments may be a result
of the greater amount of supplement offered
compared to DDG treatments. Supplements
were formulated to contain equal amounts of
CP. Dried distillers grains have a greater
concentration of CP compared to SBH, and as a
result, steers in the SBH treatment were offered
3.17 lb/d more supplement compared to steers in
the DDG treatment. However, the steers offered
the DDG treatment consumed an estimated
mean of 6.0 lb/d more hay; therefore, not all of
the differences in hay intake between
supplement types were the result of substitution
effects. Supplements were formulated to contain
equal concentrations of CP, and therefore, equal
concentrations of N. However, the greater hay
DMI observed in steers consuming DDG
resulted in 40% greater (P<0.001) N intake for
DDG-supplemented steers compared to SBHsupplemented steers (Table 1). Similarly, steers
offered DDG+Opt consumed 35% greater
(P<0.001) amounts of N/d compared to steers
offered SBH+Opt.
The greater level of N intake observed in steers
offered DDG likely contributed to greater PUN
concentrations compared to SBH. Plasma urea
nitrogen concentrations above 12 mg/dL are
associated with adequate dietary CP, and
Gain:feed (Table 1) was calculated using mean
estimated daily hay DMI and amount of
supplement offered. Co-product type affected
93
addition of Optigen® II had no effect (P=0.12)
on initial urinary N excretion. However, steers
consuming DDG and DDG+Opt excreted 56.2 g
N/d more (P<0.001) compared to steers
consuming SBH and SBH+Opt on d 0. On d 14,
Optigen had no effect (P=0.80) on urinary N
excretion, steers offered DDG excreted
approximately 63% greater (P=0.05) amounts of
urinary N compared to steers offered the SBH
treatments. On d 28, co-product type and
addition of Optigen affected urinary-N excretion
(P=0.001 and 0.01, respectively). No treatment
differences (P>0.38) were observed for urinary
N excretion on d 42.
consequently, may indicate a potential for
performance improvement through energy
supplementation (Hammond et al., 1993).
Therefore, steers offered the DDG+Opt
treatment may have exhibited improved
performance with additional dietary energy.
Additionally, Hammond et al. (1993) stated that
cattle with PUN concentrations below 9 mg/dL
are most likely to respond to protein
supplementation when maintained on a
subtropical forage-based diet. The steers offered
the SBH supplement were the only group of
steers that consistently had PUN concentrations
below 9 mg/dL, indicating that these steers may
have benefited from additional protein
supplementation.
Similar to PUN concentrations, urinary-N
excretion appears to have been related to
calculated mean daily N intake. Throughout
most of the experiment, urinary-N excretion was
greater for steers consuming DDG supplements
compared to steers consuming SBH. The
addition of Optigen® II to the supplements of
beef steers generally did not affect urinary-N
excretion. This may suggest that despite the
additional dietary N, Optigen® II did not
increase urinary-N excretion, possibly resulting
in greater N retention.
Plasma glucose concentrations (Table 2) were
not different (P=0.59) among supplement
treatments or Optigen (P=0.92) on any of the
four sampling dates.
Mean glucose
concentration during the experiment was 68.34
mg/dL. While there were differences (P=0.06)
in estimated total TDN intake (Table 1), only
about 1.32 lb/d separated the group of steers that
consumed the greatest amount of TDN
compared to those that consumed the least.
These differences were likely not sufficient to
elicit any changes in plasma glucose
concentrations.
The SBH treatments were the most effective, as
these steers exhibited the greatest feed
efficiency. Supplemental RDP did not affect
steer performance. While Optigen® II addition
increased PUN concentrations to more desirable
levels in SBH diets, it did not affect
performance.
As a result of the acclimation period prior to d 0,
treatment differences as a result of co-product
supplementation (P<0.001) were observed in
initial daily urinary N excretion (Table 2). The
Literature Cited
Chambliss and Sollenberger. 1991. Pages 74-80 in Proc. 40th Florida Beef Cattle Short Course.
Chen et al. 1992. Anim. Prod. 55:185.
Fike et al. 2002. J. Dairy Sci. 85:866.
Hammond et al. 1993. In: Proc. XVII Int. Grassl. Congr. p 1989.
Littell et al. 2006. SAS System for Mixed Models. 2nd ed.
NRC. 2000. Nutrient requirements of beef cattle. 7th rev. ed.
1
Jacqueline Wahrmund, Former Graduate Student, Matt Hersom, Assistant Professor, UF-IFAS,
Department of Animal Sciences, Gainesville, FL.
94
Table 1. Effect of co-product source and Optigen® II supplementation on steer bodyweight (BW), BW gain
and intake.
Item
DDG
Initial BW, lb
BW gain, lb/d
d 0 – 14
d 14 – 28
d 28 – 42
d 0 - 42
522
Mean hay DMI, lb/d
Total DMI, lb/d
N Intake, g/dc
TDN Intake, lb/dc
Treatmenta
DDG+Opt
SBH
522
524
2.80
0.99
1.74
1.85
3.00
1.01
1.67
1.89
2.91
1.54
1.45
1.96
15.5d
18.1d
165.65d
11.6de
15.9d
18.6d
188.05e
11.8d
9.5e
15.4e
118.02f
10.5f
SBH+Opt
SEM
515
15.6
3.19
1.34
1.81
2.07
9.8e
15.7e
139.37g
10.7ef
P-Value
CoOptigen
product
0.88
0.71
b
0.22
0.31
0.24
0.09
0.46
0.14
0.77
0.05
0.29
0.78
0.54
0.30
0.64
0.64
3.93
0.39
<0.001
<0.001
<0.001
0.007
0.62
0.52
<0.001
0.62
Gain:Feed, lb:lb
0.10d
0.10d
0.12e
0.13e
0.003
<0.001
a
Least square means; Treatment: DDG, dried distillers grains; DDG+Opt, dried distillers grains plus
Optigen® II, SBH, soybean hulls; SBH+Opt, soybean hulls plus Optigen® II.
b
Standard error of the mean, n=56.
c
Estimated total dietary intake (hay and supplement).
0.34
Table 2. Effect of co-product source and Optigen® II supplementation on steer plasma metabolite
concentrations and daily urinary excretion.
Treatmenta
Item
DDG
DDG+Opt
SBH
SBH+Opt
PUNc, mg/dL
d0
d 14
d 28
d 42
Mean glucose,
mg/dL
SEM
b
P-Value
CoOptigen
product
10.17
10.70
10.69
10.35
11.49
14.02
13.70
13.43
4.06
5.51
6.17
7.87
5.67
10.12
8.51
10.30
0.72
0.82
0.67
0.66
<0.001
<0.001
<0.001
<0.001
70.59
67.20
65.87
69.70
2.16
0.59
0.05
<0.001
<0.001
<0.001
0.92
Urinary N, g/d
d0
102.11
125.41
53.40
61.64
10.37
<0.001
0.12
d 14
162.11
144.62
77.74
110.33
33.70
0.05
0.80
d 28
130.67
180.40
92.93
118.32
15.20
0.001
0.01
d 42
113.01
110.05
112.77
141.78
22.32
0.38
0.47
a
Least square means; Treatment: DDG, dried distillers grains; DDG+Opt, dried distillers grains plus
Optigen® II, SBH, soybean hulls; SBH+Opt, soybean hulls plus Optigen® II.
b
Standard error of the mean; n=56 for PUN and glucose, n=19, 23, 27, 22 for days 0, 14, 28, 42, respectively
for urinary N.
c
Plasma urea nitrogen.
95
96
Dried Distillers Grains and(or) Soybean Hulls to Background Beef Calves Fed
Bahiagrass Forage
Jacqueline Wahrmund
Matt Hersom1
Co-products dried distillers grains or soybean hulls can be utilized as supplements for growing beef
cattle. Combinations of the two ingredients resulted in the best growth performance compared to the
individual ingredients. The price of each co-product should determine the most economic proportion of
the co-products fed.
Summary
The objective of this study was to determine the
effects of supplementing dried distillers grains
soybean hulls, or combinations of the two to
growing beef steers consuming bahiagrass hay.
Angus steers were randomly allotted to one of
four supplement treatments.
Treatments
included: 1) dried distillers grains; 2) dried
distillers grains/soybean hulls; 3) soybean
hulls/distillers grains; 4) soybean hulls.
Supplements were formulated to be isoenergetic,
and steers were individually supplemented via a
Calan Gate system for 42 d. All steers were
allowed ad libitum access to bahiagrass hay.
Supplement treatment had no effect on final
bodyweight. From d 0 to 14, average daily gain
(ADG) of dried distillers grains supplemented
steers was 0.59 lb/d less compared to any
treatments containing soybean hulls. Across all
42 d, ADG of soybean hull supplemented steers
was less than the combinations of dried distillers
grains and soybean hulls, but was not different
than steers supplemented with dried distillers
grains only. Plasma glucose concentrations
were not different between supplement
treatments. On d 0, plasma urea nitrogen
concentration did not differ between treatments.
However, on d 14, 28, and 42 the plasma
urea nitrogen concentrations of steers offered
supplements containing dried distillers grains
were greater compared to steers offered
supplements
containing
soybean
hulls.
Supplementing steers consuming bahiagrass hay
with a combination of co-products resulted in
improved ADG gain and nitrogen metabolism.
The combination of 2.11 lb of dried distillers
grains and 4.52 lb of soybean hulls optimized
calf performance.
Introduction
Bahiagrass is the most common type of forage
utilized in Florida (Chambliss and Sollenberger,
1991); however, cattle are not able to consume
enough bahiagrass to meet their nutrient
requirements at certain points of the production
cycle. Therefore, supplementation programs
must be developed to optimize beef cattle
performance. Bahiagrass in Florida generally
does not contain enough protein to meet growing
beef cattle requirements.
Low-quality tropical and subtropical grass
forages are often deficient in crude protein (CP)
relative to the protein requirements of many
classes of cattle. Therefore, cattle with greater
protein requirements, such as growing cattle,
will require additional protein supplementation
to meet the nutritional demands associated with
growth when maintained on a high-forage diet.
Dried distillers grains (DDG) are a co-product of
the corn-derived ethanol fuel industry. As
ethanol fuel production continues to increase in
the United States, DDG will become more
available to cattle producers for animal
consumption. Soybean hulls (SBH) are another
readily available co-product. The price of the
feedstuffs, as well as the nutrient needs of the
97
where:
SBW = shrunk body weight
RE = retained energy
EQSBW = equivalent shrunk body
weight,
assuming a 4% shrink, and that RE is
equal to net energy for gain (NEg).
cattle, will generally dictate the most
economically desirable supplementation program
to optimize herd performance. Combinations of
DDG and SBH were fed to determine practical
feeding applications of these two co-products.
Animals and Diets
Fifty-six Angus steers were blocked by
bodyweight (BW) and randomly assigned to one
of four treatments and one of seven pens.
Treatments included: 1) DDG (6.17 lb of DM);
2) DDG/SBH (4.25 lb DDG, 2.16 lb SBH); 3)
SBH/DDG (2.11 lb DDG, 4.52 lb SBH); 4) SBH
(6.87 lb of DM).
All steers were fed
approximately 5.95 lb of SBH for five d prior to
the initiation of the trial. Supplement treatments
began on d 0 after sampling. Bahiagrass hay
was offered to each pen, ad libitum, as large
round bales. Fresh bales were offered each wk,
and each bale was weighed and core-sampled for
analysis of chemical composition. Steers were
individually supplemented at approximately
0700 via a Calan gate system.
Statistical Analysis
The experiment was designed as a completely
randomized design, with supplement treatment
as the fixed effect (Littell et al., 2006), steer
within treatment as the random effect, and
individual steer was the experimental unit. Data
were analyzed using the Mixed procedure of
SAS v9.1 (2002, SAS Inst., Inc., Cary, NC).
Means were calculated using least squares
means, and means were separated using the Pdiff option when the overall F-value was <0.10.
Results
Steer Performance and Intake
At the initiation of the trial, steer BW (mean 605
lb, Table 1) did not differ (P=0.99) among
treatments.
Between d 0 and 14, steers
supplemented with DDG gained 55% less
(P<0.05) than steers on all other treatments.
Average daily gain from d 14 to 28 was not
different (P=0.55) among treatments. At the
completion of the study on d 42, final steer BW
was not different (P=0.79, mean = 674 lb).
From d 28 to 42, ADG did not differ (P=0.26)
among treatments; however, there was a
tendency (P=0.10) for treatment to affect overall
ADG from d 0 to 42. Steers consuming SBH
alone gained 0.37 lb/d less than steers
consuming SBH/DDG, and 0.31 lb/d less than
steers consuming DDG/SBH (P<0.05).
Sampling and Analysis
Steers were fed for 42 d, unshrunk BW were
taken on two consecutive d at the initiation (d -1,
0) and termination of the trial (d 42, 43).
Interim BW were obtained on d 14 and 28. The
two-d mean of BW was utilized to determine
initial and final BW and ADG. Blood samples
were collect for analysis of plasma urea nitrogen
(PUN) and glucose concentrations. Bodyweight
measurements and blood samples were obtained
prior to supplements being offered.
Weekly hay samples were collected from each
pen and composited for analysis of chemical
composition.
Hay and supplement total
digestible nutrients (TDN) concentrations were
determined using the equation (Fike et al.,
2002):
Supplement type affected (P=0.01) mean
estimated hay DMI (Table 1); steers
supplemented with only SBH consumed the
greatest amount of hay across the 42-d
experiment (8.48 lb/d), followed by steers
offered the SBH/DDG and DDG treatments,
which were not different (P>0.10). Differences
were also observed (P<0.05) in estimated total
DMI (Table 1), with steers offered SBH or
SBH/DDG consuming 24% more DM compared
to steers offered DDG or mostly DDG/SBH.
%TDN = [(% IVDMD * 0.59) + 32.2] *
organic matter concentration.
Because hay was fed as large round bales within
each pen, mean daily hay dry matter intake
(DMI) was calculated using the NRC (2000)
equation:
SBW = 13.91 * RE0.9116 * EQSBW-0.6837
Gain:feed (Table 1) was calculated utilizing
98
mean estimated daily hay DMI and the amount
of supplement offered, with treatment affecting
(P<0.001) gain efficiency. Steers consuming
DDG/SBH were most efficient (P<0.05),
followed by the DDG and SBH/DDG
treatments, which were not different (P>0.10).
Steers supplemented with SBH only were least
efficient, with a gain efficiency of 0.03 less than
steers supplemented with DDG and SBH/DDG,
and 0.05 less than steers supplemented with
DDG/SBH (P<0.05).
greatest (P<0.001; Table 1) for steers on the
only DDG diet, and decreased with the amount
of DDG offered, with steers offered only SBH
consuming the least amount of N/d. The greater
supply of dietary N resulted in greater amounts
of N metabolized, which appeared in the blood
as PUN. Hammond et al. (1993) suggested that
PUN concentrations above 12 mg/dL indicate
adequate dietary CP, and cattle may benefit from
energy supplementation in this situation.
Furthermore, PUN concentrations below 9
mg/dL indicate that dietary protein is
inadequate, and protein supplements may
enhance cattle performance. The steers offered
only DDG consistently had PUN concentrations
in excess of 12 mg/dL, and therefore, additional
dietary energy may have improved performance.
Additionally, steers offered only SBH never
achieved PUN concentrations above 7 mg/dL,
which indicates that protein was not sufficient to
maximize steer performance. The steers that
received a combination of co-products had PUN
concentrations that ranged from 8.4 mg/dL to
12.1 mg/dL throughout the experiment after d 0.
These results further illustrate the metabolic
advantage of supplemental protein and energy,
which tended to improve overall ADG above the
SBH supplement, and increased gain efficiency
in steers offered the DDG/SBH treatment.
Steers consuming DDG or SBH/DDG averaged
0.018 fewer (P<0.05) lb of gain per lb of feed
compared to steers consuming DDG/SBH.
Physiological Response
Prior to the initiation of the experiment, steers
were supplemented with approximately 5.95 lb/d
of SBH for five d. As a result, no treatment
differences (P=0.68) were observed in PUN
concentrations on d 0 (Table 2). However, on d
14, PUN concentration increased (P<0.01) as the
amount of DDG offered in the supplement
increased. Steers supplemented with only SBH
had a mean PUN concentration of 5.31 mg/dL.
Substituting a small amount of energy from
SBH with DDG resulted in an 85% increase
(P<0.05) in PUN concentrations of steers on the
SBH/DDG
treatment,
whereas,
steers
supplemented with the DDG/SBH treatment had
24% greater (P<0.05) PUN concentrations
compared to steers offered SBH/DDG. Steers
supplemented with DDG had the greatest
(P<0.05) PUN concentrations, with 36.9%
greater concentrations compared to DDG/SBHsupplemented steers. Similar patterns were
observed on d 28; PUN concentrations increased
(P<0.001) with the amount of DDG in the diet.
Treatment differences were observed (P<0.001)
on d 42. Steers consuming DDG only had the
greatest
PUN
concentrations;
however,
differences were not observed (P>0.10) between
steers consuming the DDG and DDG/SBH
treatments.
Additionally, there were no
differences (P>0.10) between steers on the
DDG/SBH and SBH/DDG treatments. Steers
supplemented with SBH had the lowest PUN
concentration (P<0.05).
There were no treatment differences (P≥0.78) in
plasma glucose concentrations on d 0, 14, 28,
and 42. Plasma glucose concentrations have
been shown to be related to energy intake
(Schmidt and Keith, 1983); however, differences
in total TDN intake by steers in this trial (Table
1) did not affect plasma glucose.
Economic Analysis
A simple economic analysis was conducted to
determine the most desirable supplement
combination for producers (Table 3). The prices
paid for the feedstuffs were as follows: hay,
$30/bale; DDG, $182/T; SBH, $155/T. Based
on the prices paid for the supplements, the
cost/lb of each supplement were as follows:
DDG, $0.091; DDG/SBH, $0.086; SBH/DDG,
$0.082; SBH, $0.077. The cost of BW gain was
determined based on the cost of total feed.
Steers consuming the SBH treatment had the
greatest (P<0.05) cost of BW gain at $0.681/lb,
compared to the other three treatments which
ranged from $0.499/lb to $0.590/lb. The SBH
The effects of treatment on steer PUN were
directly related to the amount of supplemental
protein offered. Total dietary N intake was
99
were the least economically efficient as a result
of their low BW gains and high hay intakes.
These results may indicate that the combinations
of co-products were more cost efficient
compared to DDG or SBH alone. The price of
each co-product should determine the most
economically desirable proportions of DDG and
SBH used to background steers.
The combination of mostly DDG was the most
efficient and economical supplement. The other
two supplements containing DDG also
outperformed the SBH only diet. Therefore, the
SBH treatment alone is not a desirable
supplement to growing steers when fed at this
level or in combination with this hay. Growing
steers require more protein than they are able to
consume from a diet of bahiagrass hay with
SBH supplementation. The cost of the coproduct supplements should dictate the most
desirable combinations to feed to growing beef
steers.
Literature Cited
Chambliss and Sollenberger. 1991. Pages 74-80 in Proc. 40th Florida Beef Cattle Short Course.
Fike et al. 2002. J. Dairy Sci. 85:866-878.
Hammond et al. 1993. In: Proc. XVII Int. Grassl. Congr. p 1989.
Littell et al. 2006. SAS System for Mixed Models. 2nd ed.
NRC. 2000. Nutrient requirements of beef cattle. 7th rev. ed.
1
Jacqueline Wahrmund, Former Graduate Student, Matt Hersom, Assistant Professor, UF-IFAS, Department
of Animal Sciences, Gainesville, FL.
100
Table 1. Effect of dried distillers grains (DDG) and/or soybean hulls (SBH) supplementation on steer
bodyweight (BW), BW gain and intake.
Item
Initial BW, lb
BW gain, lb/d
d 0 – 14
d 14 – 28
d 28 – 42
d 0 – 42
Mean hay DMI, lb/d
Total DMI, lb/d
N Intake, g/dc
TDN Intake, lb/dc
DDG
604
Treatmenta
DDG/SBH
SBH/DDG
608
606
SEMb
16.0
SBH
600
P-value
0.99
0.73d
1.98
2.05
1.59de
1.19de
2.07
2.07
1.76d
1.37e
1.78
2.36
1.83d
1.39e
1.48
1.50
1.45e
0.18
0.31
0.31
0.11
0.03
0.55
0.26
0.10
6.01de
11.45d
180.45d
8.50d
5.64d
11.32d
154.67e
8.79d
7.67ef
13.57e
142.40f
8.92e
8.48f
14.60e
122.15g
7.73f
0.64
0.64
4.48
0.20
0.01
0.001
<0.001
<0.001
Gain:Feed
0.12d
0.14e
0.12d
0.09f
0.01
<0.001
a
Least square means; Treatment: DDG, 6.17 lb dried distillers grains; DDG/SBH, 4.25 lb DDG, 2.16 lb
soybean hulls; SBH/DDG, 2.11 lb DDG, 4.52 lb SBH; SBH, 6.87 lb SBH.
b
c
Estimated total dietary intake (hay and supplement).
d, e, f, g
Means with different superscripts within a row are different (P<0.05).
Table 2. Effect of dried distillers grains (DDG) and/or soybean hulls (SBH) supplementation on steer
plasma glucose and urea nitrogen concentration.
Treatmenta
Item
DDG
DDG/SBH
SBH/DDG
PUNc, mg/dL
d0
6.75
6.17
6.13
d
e
d 14
16.57
12.10
9.80f
d 28
14.01d
11.55e
8.42f
d
de
d 42
12.53
11.86
10.24e
SBH
6.44
5.31g
5.64g
5.86f
SEMb
P-value
0.41
0.81
0.70
0.83
0.68
<0.001
<0.001
<0.001
Glucose, mg/dL
d0
77.24
74.49
75.19
74.51
3.69
0.94
d 14
78.88
76.30
79.56
76.64
3.92
0.90
d 28
80.38
75.69
76.25
76.29
4.06
0.83
d 42
80.76
75.82
76.79
75.66
4.29
0.78
a
Least square means; Treatment: DDG, 6.17 lb dried distillers grains; DDG/SBH, 4.25 lb DDG, 2.16 lb
soybean hulls; SBH/DDG, 2.11 lb DDG, 4.52 lb SBH; SBH, 6.87 lb SBH.
b
c
Plasma urea nitrogen.
d, e, f, g
101
Table 3. Economics of supplementing dried distillers grains (DDG) or soybean hulls (SBH).
Treatmenta
Item
DDG
DDG/SBH SBH/DDG
SBH
SEMb P-value
Supplement cost, $/lbc
0.091
0.086
0.082
0.077 ----d
ef
e
f
f
Feed cost, $/steer/d
0.89
0.92
0.95
0.87
0.01
0.07
Total feed, $/steer
37.43ef
38.83e
39.91f
36.53f
2.53
0.07
e
f
ef
g
Cost of gain, $/lb BW
0.590
0.499
0.554
0.681 0.03
0.003
gain/steer
a
Least square means; Treatment: DDG, 6.17 lb dried distillers grains; DDG/SBH, 4.25 lb DDG,
2.16 lb soybean hulls; SBH/DDG, 2.11 lb DDG, 4.52 lb SBH; SBH, 6.87 lb SBH.
b
c
Cost of supplements: $182/T DDG, $155/T SBH.
d
Cost of hay and supplement consumed per steer/d; hay cost, $30/bale.
e, f, g
102
Feeding Interval Effects on Growth, Puberty, and Pregnancy Rates in
Yearling Bos indicus and Bos taurus Beef Heifers
Brad Austin1
Matt Hersom
Joel Yelich
Supplementation of developing heifers with distillers grains three days/week has no negative effects on
heifer growth or reproductive performance compared to daily supplementation.
Summary
The objective of this study was to examine the
effects
of
daily
versus
three
d/wk
supplementation on growth, age at puberty,
estrous
synchronization
response,
and
pregnancy rates of yearling Brangus and Angus
heifers consuming round bale silage (RBS).
Sixty heifers (30, Angus; 30, Brangus) were
stratified by initial body weight, breed, and age
and randomly allocated to 12 pens. Pens were
randomly assigned to one of two treatments: 1)
distillers grains and soybean meal supplemented
daily; or 2) distillers grains and soy bean meal
supplemented three d/wk.
Supplement
consumption and RBS offered were similar for
both treatments. Heifers supplemented daily
had similar ADG as compared to heifers
supplemented three d/wk (1.82 vs. 1.79 lb/d).
The number of heifers reaching puberty by
breeding tended to be greater for daily fed
heifers. Synchronized pregnancy rates and total
28 day AI pregnancy rates were also similar for
both treatments. In this study, three d/wk
supplementation of developing heifers had no
effect on heifer growth rates or pregnancy rates
as compared to daily supplementation.
age. Most cattle raised in the Southeastern
United States have some degree of Bos indicus
breeding and heifers with Bos indicus breeding
tend to mature slower and reach puberty at older
ages than Bos taurus heifers. The influence of
Bos indicus breeding can negatively affect the
rancher’s success of having heifers pregnant to
calve at two yr of age.
The impact of
supplemental nutrition is increasingly important
in these situations.
Supplementation of heifers is a very common
practice, but producers are often concerned
about the labor inputs involved with
supplementation. Labor saving methods utilized
include: supplement type (liquid and selflimiting), feeding method (hand fed, self fed),
and feeding intervals (daily, three times a week,
once a week). Little data is available on the
effects of supplementing heifers at different
intervals on growth and reproductive
performance. A better understanding of the
biological effects of these labor saving
supplementation methods can lead to more
efficient development of heifers.
effects
of
daily versus
three
d/wk
supplementation on age at puberty, estrous
synchronization response, and pregnancy rates
of yearling Brangus and Angus heifers
consuming RBS.
Introduction
The development of heifers is one of the major
economic considerations in a cow-calf
operation. Heifers that calve by two years of
age have greater lifetime productivity than
heifers that calve at an older age. Heifers must
be maintained on a high plane of nutrition to
reach puberty and conceive by 14 to 15 mo of
103
Procedure
This study was conducted at the Santa Fe Beef
Unit, located near Gainesville in northern
Alachua County. Sixty heifers (n=60) were
stratified by age, body weight, and sire into 12
pens (6 pens Angus and 6 pens Brangus).
Beginning in October 2006, heifers were
supplied ad libitum access to bermudagrass
round bale silage (RBS; 51% dry matter, 12.9%
crude protein, 53.9 % total digestible nutrients)
and free choice mineral.
Heifers were
supplemented with distillers dried grains (DDG)
and soybean meal to gain approximately 1.5
lb/d, with half of the pens supplemented daily
(CON) and the remaining pens supplemented
three d/wk (3X). Soybean meal was fed to help
meet degradable intake protein requirements as
determined by the NRC computer model.
Heifers were weighed and bled weekly to
determine average daily gain (ADG) and age at
puberty. Body condition scores (BCS) and hip
heights (HH) were taken monthly. A shrunk
body weight (following a 12-h shrink) was
collected at the beginning and the end of the
trial.
Least square means were determined and
differences between means were considered
significant is P<0.05.
Results
The ADG of the heifers for the trial was greater
than predicted by the model, and ADG were
similar between treatments (P=0.83). Heifers
averaged 1.84 lb/d for the entire trial for both
treatments. Shrunk weight ADG for the trial
were also similar (P=0.72) between treatments
(CON- 1.82, 3X- 1.79 lb/d). The Angus and
Brangus heifers gains were similar (P=0.86)
regardless of treatment (Angus 1.91 vs. Brangus
1.77 lb/d). Total RBS offered was similar
(P=0.73) between treatments (CON= 17,787 lbs;
3X= 17,556 lbs), and DDG consumption was
also similar (P=0.56) between treatments
(CON=2,891; 3X=2,970 lbs). Changes in hip
height were also similar between treatments
(P=0.95; 3.7 in for CON and 3X). Heifer gains
were not impaired by supplementing three d/wk
compared to daily supplementation.
This
supports previous research conducted in cows
that three d/wk supplementation of protein feed
does not significantly affect cow performance
and therefore it can be used as means to save
labor in a feeding program.
Heifers were synchronized for artificial
insemination on d 145 of the experiment. A
CIDR was inserted concurrent with GnRH.
Seven d later the CIDR was removed and
prostaglandin was administered to synchronize
estrus. Estrus was detected for 72 h, using the
Heatwatch system, and heifers were inseminated
approximately 8-12 h after the onset of estrus by
a single AI technician. Heifers not exhibiting
estrus by 72 h after prostaglandin received
GnRH and fixed-time AI. Detection of estrus
and AI were continued for 27 d while heifers
remained in their respective pens and continued
to receive supplement treatments. Pregnancy
was diagnosed by ultrasonography 31 d after
prostaglandin at which time heifers were
removed from supplementation treatments and
pens.
Heifers in the CON treatment tended (P=0.09) to
have a greater percentage pubertal (60%) at
breeding compared to 3X heifers (40%, Table
1). It is unclear at this point if this difference is
due to the feeding regiment used (daily vs. three
d/wk) or it is just due to the limited number of
heifers in that group. Estrus response tended
(P=0.10) to be greater for CON (77%) compared
to 3X (57%). The synchronized pregnancy rates
were similar (P=0.30) for 3X (57%) compared
to CON (43%). Total 28 d AI pregnancy rates
were also similar (P=0.59) between treatments
(CON=63%;
3X=70%).
Synchronized
pregnancy rates for the heifers exceeded
previous reproductive performance for heifers at
the Santa Fe beef unit. It is important to note
that even though only 50% of the heifers had
reached puberty by the start of the breeding
season, the synchronization treatment still
resulted in a first service AI pregnancy rate of
50%. This indicates the importance of using a
Data for ADG, HH, and BCS were analyzed
using the PROC MIXED procedure of SAS.
The model statement contained the effects of
treatment, breed, and the interaction. Pen within
treatment was the random effect. Pregnancy and
puberty data were analyzed using PROC GLM.
104
synchronization treatment that utilizes a
progestagen source in inducing puberty in the
non-pubertal heifers.
In conclusion, DDG showed no negative effects
on the development of yearling Angus and
Brangus heifers in combination with RBS.
Heifers adapted easily to DDG and RBS, and
exceeded the computer modeled performance
during the study. Three-time a week feeding of
developing heifers offers a management practice
that may help significantly reduce labor cost
without sacrificing heifer growth rates or
pregnancy rates.
Table 1. Summary of reproductive performance of heifers supplemented Daily or 3X a week
Daily
P-value
3X
Pubertal at AI (%)
18/30 (60)
12/30 (40)
a
Estrous response (%)
23/30 (77)
17/30 (57)
b
Synchronized pregnancy rate (%)
13/30 (43)
17/30 (57)
c
30 d AI pregnancy rate (%)
19/30 (63)
21/30 (70)
a
Percentage of heifers displaying estrus during the 3 d after PGF2 of the total treated.
b
0.09
0.10
0.30
0.59
Percentage of heifers pregnant during the synchronized breeding of the total treated
c
Percentage of heifers pregnant to AI during the dirst 30 d of the breeding season of the total number
of heifers.
1
Brad Austin, Gradute Student; Matt Hersom, Assistant Professor; Joel Yelich, Associate
Professor, UF-IFAS Animal Sciences, Gainesville, FL
105
106
Programmed Feeding Effects on Growth, Puberty, and Pregnancy Rates in
Yearling Bos indicus and Bos taurus Beef Heifers
Brad Austin1
Matt Hersom
Joel Yelich
Programmed supplementation of heifers can have a negative impact on the growth and
reproductive performance of heifers if heifers are placed under extreme nutritional stress.
Summary
effects of programmed supplementation on
growth, age at puberty, estrous synchronization
response, and pregnancy rates of yearling
Brangus and Angus heifers consuming round
bale silage (RBS). Sixty heifers (30 Angus, 30
Brangus) were stratified by initial body weight,
breed, and age and randomly allocated to 12
pens. Pens were randomly assigned to one of
two treatments: 1) RBS and dried distillers
grains (DDG) supplemented 3 d/wk for duration
of experiment (174 d, CON) or, 2) RBS ad
libitum for the first 88 d and RBS and DDG
supplemented 3 d/wk from d 89-174 (L-H). All
heifers were offered ad libitum bermudagrass
RBS during the trial. Round bale silage quality
was lower than predicted causing poorer
performance than expected. Heifers in the L-H
treatment had decreased average daily gain
(ADG), percentage of heifers pubertal at d 89
and at AI, 28-d pregnancy rates, and overall
pregnancy rates compared to heifers
supplemented for the entire trial. Synchronized
pregnancy rates (46 vs 33%) and conception
rates (50 vs 53%) were similar (P>0.05)
between CON and L-H, respectively. In this
study, decreased growth rates experienced by LH heifers during the first phase of the trial were
very significant.
These heifers did not
experience the predicted compensatory gain
during the second period of the trial which had
dramatic effects on heifer reproductive
performance.
Introduction
The development of replacement heifers is one
of the major economic considerations in a cowcalf operation. Heifers that calve by two yr of
age have greater lifetime productivity than
heifers that calve at an older age. Heifers must
be maintained on a high plane of nutrition to
reach puberty and conceive by 14 to 15 mo of
age.
Therefore, management decisions
regarding replacement heifers should focus on
factors that promote early onset of puberty and
early calving.
Most cattle raised in the Southeastern United
States have some degree of Bos indicus breeding
and heifers with Bos indicus breeding tend to
mature slower and reach puberty at older ages
than Bos taurus heifers. The influence of Bos
indicus breeding can negatively affect the
rancher’s success of having heifers pregnant to
calve at two yr of age.
The impact of
supplemental nutrition is increasingly important
in these situations.
There has been a great deal of research
examining the effects of timing of gain on
puberty in heifers. Research has shown that
programmed feeding of heifers can have positive
effects on attainment of puberty, establishment
of pregnancy, and future production of the
animal. Managing heifers to attain puberty with
decreased feed inputs and then taking advantage
of compensatory gains may have economic
advantages.
107
Altering the feeding patterns of heifers to affect
weight gain is a management tool that can help
to decrease the feed cost involved with
developing replacement heifers. Most of this
research has been conducted with Bos taurus
animals in drylot situations. No data is available
on Bos indicus X
Bos taurus
heifer
performance, or heifer performance in a forage
based system.
Heifers were synchronized for artificial
insemination on d 173 of the experiment. A
CIDR was inserted concurrent with GnRH.
Seven days later the CIDR was removed and
prostaglandin was administered to synchronize
estrus. Estrus was detected for 72 h, using the
Heatwatch system, and heifers were inseminated
approximately 8-12 h after the onset of estrus by
a single AI technician. Heifers not exhibiting
estrus by 72 h after prostaglandin received
GnRH and were timed-AI. Estrous detection
and AI were continued for 27 d while heifers
remained in their respective pens and continued
to receive supplement treatments. Pregnancy
was diagnosed by ultrasonography 31 d after
prostaglandin at which time heifers were
removed from supplementation treatments and
pens. Heifers were grouped by breed and placed
with a clean-up bull for 25 d. Final pregnancy
diagnosis was performed by ultrasonography 28
d after the clean-up bull was removed.
effects of programmed supplementation on
growth, age at puberty, estrous synchronization
response, and pregnancy rates of yearling
Brangus and Angus heifers consuming RBS.
Procedure
This study was conducted at the Santa Fe Beef
Unit, located near Gainesville in northern
Alachua County. Sixty heifers (n=60) were
divided by age, body weight, and sire into 12
pens (6 pens Angus and 6 pens Brangus).
Beginning in October 2007, heifers were
supplied ad libitum access to bermudagrass RBS
(54% dry matter, 7.9% crude protein, 53.9 %
total digestible nutrients) and free choice
mineral. One half of the heifers (3 pens Angus
and 3 pens Brangus, CON) were supplemented
with distillers dried grains (DDG) to gain
approximately 1.5 lb/d as determined by NRC
computer model. The other half of the pens (LH) were offered only RBS for the first 88 d
(Phase 1). For the final 86 d distillers grains
were supplemented at a rate to provide a gain of
approximately 3.0 lb/d.
Results
The ADG of the heifers was lower than
predicted by computer modeling due to poor
RBS quality. During phase 1 of the trial, CON
heifers had greater (P<0.05) ADG than L-H
heifers (1.25 vs. -0.22 lb/d). The performance of
the L-H heifers was worse than expected and
can be associated with poor forage quality.
During phase 2 of the trial ADG tended
(P=0.07) to be greater for L-H (1.63 lb/d)
compared to CON (1.34 lb/d).
The
compensatory gain of the L-H heifers was not as
great as anticipated. The ADG and shrunk ADG
for the entire trial were greater (P<0.05) for the
CON heifers compared to the L-H heifers (1.19
vs. 0.68 lb/d; 0.98 vs. 0.53 lb/d, respectively).
Because of this the final body weights of the
CON heifers were 100 lbs greater than the L-H
(P=0.002; 771 vs. 684 lbs; Table 1) at the
conclusion of the trial.
The weight loss
experienced by the L-H heifers during phase 1
was too great for them to overcome during phase
2. These results enforce the necessity of high
quality forages when developing heifers.
Prior to the start of the and at the conclusion of
the experiment, heifers were withheld from
water and feed for approximately 12 h to obtain
a shrunk body weight (SBW) and hip height
(HH). At the beginning, middle and end of the
trial a body length (BL) and heart girth (HG)
were taken on each heifer. Ultrasound
measurements of ribeye area (REA) and rump
fat were obtained on d 16, 89, and 174.
Blood samples were collected on d 79 and 89 to
determine puberty status of the heifers. Heifers
were weighed and bled weekly during phase 2 to
determine average daily gain (ADG) and age at
puberty.
Heifers in the CON treatment had greater
(P<0.05) HG, BL, and HH at d 89 and 174 than
L-H heifers (Table 1). The CON heifers had
greater (P<0.05) REA compared to L-H on d 89
108
(7.24 vs 5.43 in2) and on d 174 (8.11 vs 7.01
in2), respectively.
Rump fat was greater
(P<0.05) for CON (0.17 in) compared to L-H
(0.12 in) on d 89 but were similar (P>0.10) for
CON (0.17 in) compared to L-H (0.15 in) on d
174.
In conclusion, data from this experiment
indicates the importance of forage quality in
heifer development.
The data further
emphasizes the importance of providing heifers
the appropriate nutrition to maximize their
growth potential and reach puberty prior to
breeding. A nutritionally induced stress on
growing heifers can have a great impact on
growth and reproductive performance.
The percentage of CON heifers pubertal after the
first 87 days and at AI (13% and 33%
respectively) was significantly greater (P<0.05)
than L-H heifers (3% and 7%, Table 2). This
difference is attributable to the lower BW and
decreased ADG of the L-H heifers during the
trial. Estrous response (73 vs 40%), 30 d AI
pregnancy rates (83 vs 56%), and overall
pregnancy rates (93 vs 66%) were greater (P
<0.05) for CON compared to L-H, respectively.
Synchronized pregnancy rates (46 vs 33%) and
conception rates (50% for both) were similar
(P>0.05) between CON and L-H, respectively.
It is important to note that the synchronized
pregnancy rates were higher than the number of
heifers pubertal at AI. This reinforces the
importance of using a synchronization treatment
that utilizes a progestagen source to induce
puberty in non-pubertal heifers. These results
reinforce the importance of nutrition and weight
gain prior to breeding to induce puberty and
increase the heifer’s chances of becoming
pregnant during the breeding season.
1
Brad Austin, Gradute Student; Matt Hersom, Assistant Professor; Joel Yelich, Associate Professor, UFIFAS Animal Sciences, Gainesville, FL
109
Table 1. Summary of growth performance of program supplemented
heifers
Body weight, lb
d0
d 89
d 174
Hip height, in
d0
d 89
d 174
Heart girth, in
d0
d 89
d 174
Body length, in
d0
d 89
d 174
CON
L-H
P value
565
658
772
566
545
684
0.93
0.0002
0.001
45.07
47.26
48.33
44.92
45.85
47.09
0.56
0.002
0.004
59.11
62.47
65.44
58.39
57.98
62.53
0.15
<0.0001
0.001
26.18
39.75
42.51
26.38
38.18
40.55
0.45
0.003
0.002
Table 2. Summary of reproductive performance of program supplemented heifers
Pubertal at d 87 (%)
Pubertal at d 174 (%)
Estrous response (%)a
Conception rate (%)b
Synchronized pregnancy rate (%)c
d
30 d AI pregnancy rate (%)
Overall Pregnancy rate (%)
CON
4/30 (13)e
10/30 (33)e
22/30 (73)e
11/22 (50)
L-H
1/30 (3)f
2/30 (7)f
12/30 (40)f
6/12 (50)
14/30 (46)
10/30 (33)
e
17/30 (56)f
17/30 (66)f
25/30 (83)
28/30 (93)e
a
Percentage of heifers displaying estrus during the 3 d after PGF2 of the total treated.
c
Percentage of heifers pregnant during the synchronized breeding of the total treated
d
Percentage of heifers pregnant to AI during the first 30 d of the breeding season of the
total number of heifers.
e, f
Means without a common superscript within a row differ (P<0.05)
b
110
Mineral Concentrations of Cool-Season Pasture Forages in North Florida
during the Winter-Spring Grazing Season: I. Macro Minerals
G. Chelliah1
Bob Myer
Jeff Carter
Lee McDowell
Nancy Wilkinson
Ann Blount
Pasture forage species and blend, pasture establishment method, year and, in particular, month of
grazing season can influence concentrations of calcium (Ca), phosphorus (P), magnesium (Mg), and
potassium (K), but not sodium (Na), in cool-season annual grass pasture forage. .
Summary
Concentrations of selected macro minerals (Ca,
P, Na, K, and Mg) were determined from coolseason annual grass pasture forages over four
consecutive late fall-winter-spring grazing
seasons (2001-2005). Forage samples were
taken from eight experimental pastures used in
beef cattle grazing trials. Two, 2-yr experiments
were conducted; animal and pasture data were
reported previously (Myer and Blount, 2005 and
2007). Each experiment was of a similar 2x2
design comparing clean-tilled vs. sod-seeded
pastures with two different forage combinations
(Exp. 1, rye + oats vs. rye + oats + ryegrass;
Exp. 2, oats + ryegrass vs. ryegrass only).
Pastures were planted in Oct or Nov, and
grazed (and sampled) starting Nov, Dec, Jan or
Feb and ending Apr or May. The overall mean
concentrations for Exp. 1 and 2, respectively
were (% of dry matter): Ca, 0.31 and 0.31; P,
0.42 and 0.35; Na, 0.03 and 0.04; K, 3.2 and
2.6; and Mg, 0.26 and 0.16. Year affected
(P<0.05) P, K and Mg concentrations within
each experiment, but not Ca or Na. Pasture
planting method affected (P<0.05) Ca and P in
Exp. 2, and Mg in Exp.1. Forage treatment
affected (P<0.05) Ca, K and Mg in Exp. 2.
Sampling month affected (P<0.05) all minerals
evaluated in both experiments except Na.
Results indicate that forage type, pasture
planting method, year, and especially month
within year can affect concentrations of macro
minerals of annual cool-season grass pasture
forages in the southeastern USA.
Introduction
Cool-season grass annuals, such as oats (Avena
sativa), rye (Secale cereale) and annual ryegrass
(Lolrum multifloram), are commonly planted to
provide forage for grazing by beef cattle during
the late fall to spring period in the southeastern
USA when permanent warm-season pastures are
dormant. Depending on moisture and weather,
the grazing period can start as early as late
November and last until early June, but the start
can be as late as February and can end as early
as late April. The annual forages are planted
during the fall (Oct or Nov), and can be seeded
directly into dormant warm-season pasture (sodseeding) or planted into a clean-tilled, prepared
seedbed. These forages are highly digestible
and high in energy and protein; however, there is
limited information in regards to concentrations
of various nutritionally important minerals. The
111
combinations and seeding rates. Within yr,
initial fertilization and liming was based on soil
fertility analysis; the pastures were top-dressed
twice with N, each time with 75 lb N/ac, within
each yr. The soils at the experimental site are
well drained, acidic, and sandy (fine loamy,
kaolintic, thermic Kandiudults) typical of the
Southern Coastal Plain. Soil type was consistent
across the eight pastures. Cattle were provided a
free choice mineral supplement at all times
while grazing (Purina Dixie H/M H/SE, Purina
Mills, St. Louis, MO).
purpose of this study was to measure monthly
concentrations of selected macro and trace
minerals of annual cool-season grass pasture
forages of various combinations that were either
sod-seeded or planted into a clean-tilled,
prepared seed bed during the late fall-winterspring grazing season in north Florida.
This report will present the results of the macro
minerals of Ca, P, Na, K and Mg. A companion
paper published elsewhere in the 2009 Florida
Beef Report (Chelliah et al., 2009) will present
results of analyses of selected trace minerals.
Pastures were sampled twice mo and samples
were pooled by month for mineral analyses. Not
all months were represented for each yr,
however, the months of February, March and
April were represented for each yr of each
experiment; February, March and April data
were used to determine differences due to forage
treatment, pasture establishment method, and
year within experiment. More details about
pasture and grazing management, animal
information, and forage sampling procedures
can be found in previous publications (Myer and
Blount, 2005 and Myer and Blount, 2007).
Procedure
Pasture forage mineral concentrations were
determined as part of a grazing study. The study
consisted of two cool-season beef cattle grazing
experiments conducted at the North Florida
Research and Education Center (NFREC) of the
University of Florida located at Marianna (31 N
Lat.). Each experiment lasted two yr, resulting in
four consecutive yr of testing from 2001 to 2005
during the late fall-winter-spring grazing season.
Macro mineral concentrations were determined
from forage samples taken from eight, 3.2 ac
experimental pastures per yr used in the two
grazing experiments.
Data were analyzed as a 2x2 randomized
complete block design. The models evaluated
pasture
forage
treatment
and
pasture
establishment method as fixed effects, and yr as
random. Monthly mineral concentrations for
each experiment also were analyzed using
repeated measures model with mo as the
repeated measure. The experimental unit was the
individual pasture.
The two, two-year experiments conducted were
each of a similar 2x2 design comparing cleantilled vs. sod-seeded pastures with two different
forage combinations (simple vs. more complex
blend; Exp. 1, small grains only – rye and oats
vs. small grains plus ryegrass; Exp. 2, ryegrass
only vs. ryegrass plus oats). There were two
pastures per treatment combination per yr within
each experiment. For the tilled pastures, the
forages were planted into a clean-tilled, prepared
seedbed, and for the sod-seeded pastures,
forages were planted, using a no-till seed drill,
into dormant bahiagrass. The experimental coolseason pastures were planted in October or
November of each year, and grazed and sampled
starting in November, December, January or
February, and ending in April or May (the start
and end varied between years due to weather
conditions – pastures were grown under dry land
conditions). University of Florida/IFAS
recommendations were followed in regards to
planting times of the various pasture
Results
Animal and pasture results were reported
previously (Myer and Blount, 2005 and 2007).
Cool-season annual grass species chosen reflect
what is commonly grown in the Southern
Coastal Plain region of the southeastern USA.
Most cool-season annual pastures planted,
however, are mono-crops in this region. Average
monthly rainfall and daily temperatures over the
four study yr during October to May period were
similar to the 30-yr average at Marianna, except
for rainfall in January and May where amounts
averaged 30 to 50% less over the four yr.
October, November, April, and May tended to
112
be warmer than the 30-yr average. As expected,
there was yr to yr variation which probably
affected mineral concentrations noted for yr to
yr. As such, results were averaged over yr as
most producers are interested in what may be
expected for an average yr instead of for a
particular yr.
(hypomagnesaemia), especially during the early
spring months.
Overall mean concentrations for each
experiment for each mineral measured in the
pasture forages is presented in Table 3. From the
results of both experiments, concentrations in
annual cool-season pasture forage averaged
(mean ± one standard deviation; dry matter
basis) 0.31 ± 0.05% for Ca, 0.38 ± 0.04% for P,
0.04 ± 0.01% for Na, 2.9 ± 0.3% for K, and 0.21
± 0.03% for Mg. The concentrations of Ca, P,
and Mg are at the low end of concentration
ranges previously reported, K at the high end,
and Na in the middle (Table 3). However, it
should be emphasized that much variation in
concentration was noted for each mineral
analyzed, especially for Mg (Table 3).
Pasture establishment method affected (P<0.05)
forage concentrations of Mg in Exp. 1, and Ca
and P in Exp. 2 (Table 1). Pasture forage
treatment affected (P<0.05) Ca, K, and Mg
concentrations in Exp 2 only (Table 1).The
significant differences noted above due to
pasture establishment method or forage
treatment, however, were small (Table 1).
Year affected (P<0.05) pasture forage P, K, and
Mg concentrations within each experiment, but
not Ca or Na (means not shown); Mg in
particular was affected by yr. No forage
treatment and pasture establishment interactions,
or pasture treatment by yr interactions (P>0.05)
were noted.
Overall, for beef cattle grazing cool-season
annual grass pastures evaluated in this study,
forage Na would be very deficient; Ca slightly
deficient, P and Mg marginally deficient, and K
would be in excess (Table 3).
Month within yr affected (P<0.05) pasture
forage concentrations of all minerals evaluated
in both experiments except Na and possibly Ca.
Calcium was different in Exp.1 but not Exp. 2,
and if averaged over the two experiments, Ca
was fairly constant from mo to mo – 0.29 to
0.33% (Table 2). Forage concentrations of P
and K were greatest during the winter and
declined during spring with lowest levels noted
in May; Mg was least in early spring (Table
2).There was considerable variation in forage
concentrations of each mineral evaluated within
experiment (Table 3).
Results indicated that annual cool-season pasture
forage treatment, pasture forage establishment
method, and year, while not consistent between
experiments, can influence pasture forage
concentrations of Ca, P, K, and Mg, but have
little influence on Na. Month within yr of the
grazing season appeared to have the greatest
influence
on
forage
macro
mineral
concentrations evaluated, especially P and K.
The low forage Mg, combined with high K, may
be a potential deficiency problem for beef cattle
which
can
result
in
grass
tetany
113
Literature Cited
Chelliah, G., et al. 2009 Florida Beef Report.
Ensminger M. E., et al. 1990. Feeds and Nutrition. The Ensminger Publishing Co., Clovis, CA,
USA. pp 1265-1511.
Myer, R. O., and A. R. Blount. 2005 Florida Beef Report. pp 19-24.
Myer, B., and A. Blount. 2007 Florida Beef Report. pp 23-27.
NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. Nat’l. Acad. Sci., Washington, DC,
USA.
Acknowledgment
The assistance of Harvey Standland, John Crawford, Meghan Brennan, Mary Maddox, Mary
Chambliss, Tina Gwin, Jeff Jones and the staff at the NFREC Beef Unit is gratefully
acknowledged. Partial support was provided by Orange Hill Soil Conservation District, Chipley,
FL.
1
G. Chelliah, Former Graduate Student; Bob Myer, Professor, UF-IFAS, North Florida Research
and Education Center (NFREC), Marianna, FL; Jeff Carter, Former Assistant Professor, UF-IFAS,
NFREC, Marianna; Lee McDowell, Professor Emeritus, UF-IFAS, Department of Animal Sciences,
Gainesville, FL, Nancy Wilkinson, Chemist, UF-IFAS, Department of Animal Sciences,
Gainesville, Fl; and Ann Blount, Associate Professor, UF-IFAS, NFREC, Marianna, FL.
114
Table 1. Main means of macro mineral concentrations of annual cool-season
pasture forages during the late fall-winter-spring grazing season in north Florida
(% of dry matter).
Mineral
Ca
P
Na
K
Mg
a
Exp.
1
2
1
2
1
2
1
2
1
2
a
Cultivation
SSb
PSc
0.33
0.33
0.34
0.28
0.40
0.43
0.34
0.36
0.03
0.03
0.04
0.04
3.2
3.3
2.7
2.6
0.23
0.28
0.17
0.16
Forage Trt.
Simpled
Blende
0.30
0.32
0.35
0.27
0.42
0.41
0.35
0.34
0.03
0.03
0.04
0.04
3.2
3.3
2.7
2.5
0.26
0.25
0.18
0.15
SEM
0.01
0.02
0.01
0.01
0.002
0.001
0.06
0.04
0.01
0.01
f
Significanceg
Cult.h
Foragei
NS
NS
*
*
NS
NS
*
NS
NS
NS
NS
NS
NS
NS
NS
*
*
NS
NS
*
CxFj
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
Exp. 1, 2001-2002 and 2002-2003 grazing seasons; and Exp. 2, 2003-2004 and 2004-2005.
b
SS = sod-seeded pastures
c
PS = prepared seedbed (clean-tilled) pastures.
d
Simple = mono-culture or simple blend of forage species in pastures (Exp. 1, small grains-rye
and oats; Exp. 2, ryegrass).
e
Blend of forage species in pastures (Exp. 1, small grains plus ryegrass; Exp. 2, oats plus
ryegrass).
f
Standard error of the mean; n = 8.
g
Significance of difference; * = significantly different (P<0.05), and NS = non-significant
(P>0.05).
h
Pasture establishment method (SS vs. PS).
i
Pasture forage type or treatment (simple vs. blend).
j
Establishment method by forage treatment interaction.
115
Table 2. Monthly concentrations of macro minerals in annual cool-season pasture forages during
the late fall-winter-spring grazing seasons in north Florida (% of dry matter).
Sampling month
Exp.a Nov
Dec
Jan
Feb
Mar
Apr
May SEMb Significancec
1
0.37 0.37 0.33 0.31 0.30 0.33 0.31
0.02
*
2
0.25 0.26 0.26 0.26 0.30 0.33 0.30
0.04
NS
P
1
0.43 0.43 0.47 0.44 0.43 0.38 0.32
0.02
**
2
0.44 0.44 0.32 0.34 0.34 0.36 0.36
0.02
**
Na
1
0.04 0.03 0.03 0.03 0.03 0.04 0.04 0.003
NS
2
0.04 0.04 0.04 0.04 0.04 0.04 0.04 0.004
NS
K
1
3.8
4.2
3.8
3.3
3.3
3.1
2.3
0.2
**
2
3.8
4.2
3.2
3.0
3.0
2.6
2.2
0.2
**
Mg
1
0.31 0.29 0.28 0.25 0.24 0.27 0.27
0.02
*
2
0.18 0.16 0.14 0.14 0.16 0.17 0.16
0.01
**
a
Mineral
Ca
b
Standard error of the mean; average n = 8 (varied from 4 (Nov) to 16 (Feb, Mar, Apr) within
experiment).
c
Significance due to month within experiment: ** = highly significant (P<0.01), * = significant
(P<0.05), and NS = non-significant (P>0.05).
Table 3. Overall means and ranges of macro mineral concentrations of annual cool-season grass
pasture forages from each experiment (% of dry matter).
Exp.a
Meanb
1 S.D.c
Ranged
Requiremente
Reportedf
1
0.31
0.04
0.25 to 0.44
0.5
0.32 to 0.65
2
0.31
0.06
0.10 to 0.46
P
1
0.42
0.04
0.28 to 0.54
0.3
0.23 to 0.41
2
0.35
0.03
0.27 to 0.52
Na
1
0.03
0.01
0.02 to 0.05
0.1
0.01 to 0.11
2
0.04
0.01
0.02 to 0.05
K
1
3.2
0.3
2.0 to 5.4
0.6
1.7 to 3.4
2
2.6
0.2
2.0 to 4.3
Mg
1
0.26
0.03
0.18 to 0.42
0.1
0.20 to 0.35
2
0.16
0.02
0.11 to 0.22
a
Mineral
Ca
b
Overall mean across all treatments (n = 16).
c
One standard deviation.
d
Lowest or highest monthly concentration obtained from a treatment within year within experiment
(n = 2).
e
Suggested requirement for growing beef cattle heifers (500 to 900 lb; NRC 2000).
f
Other reported concentrations for rye, oats and ryegrass fresh forage (dry matter basis); data from
Ensminger et al., 1990, and NRC, 2000.
116
Mineral Concentrations of Annual Cool Season Pasture Forages in North
Florida during the Winter-Spring Grazing Season: II. Trace Minerals
G. Chelliah1
Bob Myer
Jeff Carter
Lee McDowell
Nancy Wilkinson
Ann Blount
Pasture forage species and blend, pasture establishment method, year, and month of grazing season can
influence concentrations of copper (Cu), zinc (Zn), selenium (Se), cobalt (Co), and, in particular,
manganese (Mn) and iron (Fe) in annual cool-season grass pasture forage.
Summary
Concentrations of selected trace minerals (Cu,
Fe, Zn, Mn, Co, Se) were determined from
annual cool-season grass pasture forages over
four consecutive winter-spring grazing seasons
(2001-2005). Twice monthly forage samples
were taken from eight experimental pastures
used in beef cattle grazing trials. Two, 2-yr
experiments were conducted; animal and
pasture data were reported previously. Each
experiment was of a similar 2x2 design
comparing clean-tilled vs. sod-seeded pastures
with two annual forage combinations (Study 1,
rye + oats vs. rye + oats + ryegrass; Study 2,
oats + ryegrass vs. ryegrass only). Pastures
were planted in Oct or Nov, and grazed
(sampled) starting Nov, Dec, Jan or Feb and
ending Apr or May.
The overall mean
concentrations of pasture forage for Exp. 1 and
2 respectively were (ppm of dry matter): Cu, 6.4
and 5.2; Fe, 88 and 68; Zn, 38 and 42; Mn, 105
and 114; Co, 0.06 and 0.06; and Se, 0.05 and
0.06. Year affected (P<0.05) forage Cu, Fe, Zn,
and Se in Exp. 1 and Fe and Zn in Exp. 2.
Cu, Fe, Zn, and Mn in Exp. 1 and Mn and Se in
Exp. 2. Forage treatment affected (P<0.05) Zn
in Exp. 1 and Cu, Fe, Zn, Mn, and Co in Exp. 2.
Sampling month affected (P<0.05) all minerals
in both experiments except Cu and Zn in Exp. 2;
monthly Se and Co were not evaluated due to
limited analyses. Results indicate that forage
type, pasture establishment method, year, and
month of grazing season can affect
concentrations of trace minerals of annual coolseason grass pasture forages in the southeastern
USA.
Introduction
Cool-season annual grasses, such as oats (Avena
sativa), rye (Secale cereale) and annual ryegrass
(Lolrum multifloram) are commonly planted to
provide forage for grazing by beef cattle during
the late fall to spring period in the southeastern
USA when permanent warm-season grass
pastures are dormant. Depending on moisture
and weather, the grazing period can start as early
as late November and last until early June, but
the start can be as late as February and can end
as early as late April. The annual forages are
planted during the fall (Oct or Nov), and can be
seeded directly into dormant warm-season
pasture (sod-seeding) or planted into a cleantilled, prepared seedbed. These forages are
highly digestible and high in energy and protein;
however, there is limited information in regards
to concentration of various nutritionally
important minerals. The purpose of this study
was to measure monthly concentrations of
selected macro and trace minerals in annual
cool-season grass pasture forage of various
117
combinations that were either sod-seeded or
planted into a clean-tilled, prepared seedbed
during the late fall-winter-spring grazing season
in north Florida.
at random, were analyzed for Se and Co for each
yr in each experiment. Further information about
planting, fertilization, and management of
pastures is presented in a companion paper
published elsewhere in the 2009 Florida Beef
Report (Chelliah et al., 2009). Cattle were
provided a free choice mineral supplement at all
times while grazing (Purina Dixie H/M H/SE,
Purina Mills, St. Louis, MO).
This report will present the results of the trace
minerals of Cu, Zn, Fe, Mn, Co and Se. A
companion report (Chelliah et al., 2009) will
present results of analyses of selected macro
minerals and is presented elsewhere in the 2009
Florida Beef Report.
Data were analyzed as a 2x2 randomized
complete block design. The models evaluated
pasture
forage
treatment
and
pasture
establishment method as fixed effects, and yr as
random. Monthly mineral concentrations for
each experiment also were analyzed using
repeated measures model with mo as the
repeated measure. The experimental unit was the
individual pasture.
Procedures
Pasture forage mineral concentrations were
determined as part of a grazing study. The study
consisted of two cool-season beef cattle grazing
experiments conducted at the North Florida
Research and Education Center (NFREC) of the
University of Florida located at Marianna (31 N
Lat.). Each experiment lasted two yr, resulting in
four consecutive yr of testing from 2001 to 2005
during the late fall-winter-spring grazing season.
Trace (micro) mineral concentrations were
determined from forage samples taken from
eight, 3.2 ac experimental pastures per yr used in
the two grazing experiments.
Results
Animal and pasture results were reported
previously (Myer and Blount, 2005 and 2007).
Cool-season annual grass species chosen reflect
what is commonly grown in the Southern
Coastal Plain region of the US. Most coolseason annual pastures planted, however, are
mono-crops in this region. Average monthly
rainfall and daily temperatures over the four
study yr during October to May period were
similar to the 30-yr average at Marianna, except
for rainfall in January and May where amounts
averaged 30 to 50% less over the four yrs.
October, November, April and May tended to be
warmer than the 30-yr average. As expected,
there was yr to yr variation which probably
affected pasture forage mineral concentrations
noted for yr to yr. As such, results were
averaged over yrs as most producers are
interested in what may be expected for an
average yr.
The two, two-year studies conducted were each
of a similar 2x2 design comparing clean-tilled
vs. sod-seeded pastures with two different forage
combinations (simple vs. more complex blend;
Exp. 1 small grains only – rye and oats vs. small
grains plus ryegrass; Exp. 2, ryegrass only vs.
ryegrass plus oats). There were two pastures per
treatment combination per year within each
experiment. Pastures were planted in October or
November of each year, and grazed and sampled
starting November, December, January or
February, and ending April or May (the start and
end varied between years due to weather
conditions – pastures were grown under dry land
conditions).
forage concentrations of Cu, Zn, Fe, and Mn in
Exp. 1, and Mn and Se in Exp. 2 (Table 1).
Pasture forage treatment affected (P<0.05)
forage concentrations of Zn in Exp. 1, and Cu,
Zn, Fe, Mn, and Co in Exp. 2 (Table 1).
Pastures were sampled twice mo and samples
were pooled by month for mineral analyses. Not
all months were represented for each yr,
however, the months of February, March and
April were represented for each yr of each
experiment and were used in statistical analyses
to evaluate the effect of yr, forage type, and
pasture establishment method. Due to high
costs, only a limited number of samples, chosen
Year affected (P<0.05) Cu, Zn, Fe and Se
pasture forage concentrations in Exp. 1, but only
affected Zn and Fe in Exp. 2 (means are not
118
shown). No pasture establishment method by
forage treatment or year by treatment
combination interactions (P>0.05) were noted.
would be deficient, Zn would be marginal, and
Fe and Mn would be adequate (Table 3).
Month within yr affected (P<0.05) pasture
forage concentrations of Cu, Zn, Fe and, Mn in
Exp. 1 but only Fe and Mn in Exp. 2 (Table 2).
Month by mo results of Se and Co are
incomplete due to limited number of samples
analyzed. In general, forage concentrations of
Fe decreased and Mn increased as the grazing
season progressed (Table 2).Considerable
variation in concentrations of the trace minerals
in the pasture forage samples, however, were
noted within experiments (Table 3).
Results indicated that annual cool-season pasture
forage type, pasture establishment method, and,
yr, while not consistent between the
experiments, can influence pasture forage
concentrations of Cu, Zn, Fe, Mn, Co and Se.
The significant differences noted due to forage
treatment and pasture establishment method;
however, were small. Again, while not
consistent, pasture forage trace mineral
concentrations can also be influenced by mo
during the grazing season, especially Fe and Mn.
The high Fe early on in the grazing season noted
in Exp. I but not Exp. 2 may have been the result
of soil contamination. Soil, which is high in Fe,
can splash on to the plant after a rain.
Overall mean pasture forage concentrations and
variation noted for the trace minerals measured
is summarized in Table 3. From the results
obtained in both experiments, concentrations
(mean ± one standard deviation; dry matter
basis) in cool-season annual grass forages
evaluated averaged 5.8 ± 0.8 ppm for Cu, 78 ±
14 ppm for Fe, 40 ± 4 ppm for Zn, 110 ± 14
ppm for Mn, 0.04 to 0.06 ± 0.02 ppm for Co,
and 0.055 ± 0.01 ppm for Se. The ranges for Cu
and Se are similar to those previously reported;
Fe is at the low end, Zn at the high end, and Mn
above (Table 3). However, it should be
emphasized that there was much variation in the
concentration of each mineral evaluated,
especially, Fe.
Overall, for beef cattle grazing annual coolseason grass pastures, forage Cu, Se and Co
119
Literature Cited
1
Chelliah, G., et al. 2009 Florida Beef Report.
Ensminger, M. E., et al. 1990. Feeds and Nutrition. The Ensminger Publishing Co., Clovis, CA,
USA. pp 1265-1511.
Myer, R. O. and A. R. Blount. 2005 Florida Beef Report. pp 23-27.
Myer, B. and A. Blount. 2007 Florida Beef Report. pp 19-24.
NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. Nat’l. Acad. Sci.,
Washington, DC, USA.
Acknowledgement
The assistance of Harvey Standland, John Crawford, Meghan Brennan, Mary Maddox, Tina,
Gwin, Mary Chambliss, Jeff Jones, and the staff at the NFREC Beef Unit is gratefully
acknowledged. Partial support was provided by Orange Hill Soil Conservation District,
Chipley, FL.
1
G. Chelliah, Former Graduate Student; Bob Myer, Professor, UF-IFAS, North Florida Research and
Education Center (NFREC), Marianna, FL; Jeff Carter, Former Assistant Professor, UF-IFAS,
NFREC, Marianna; Lee McDowell, Professor Emeritus, UF-IFAS, Department of Animal Sciences,
Gainesville, FL, Nancy Wilkinson, Chemist, UF-IFAS, Department of Animal Sciences, Gainesville,
Fl; and Ann Blount, Associate Professor, UF-IFAS, NFREC, Marianna, FL.
120
Table 1. Trace mineral concentrations of annual cool-season grass pasture forages during the late
fall-winter-spring grazing season in north Florida (ppm of dry matter).
Mineral
Cu
Fe
Zn
Mn
Co
Se
a
a
Exp.
1
2
1
2
1
2
1
2
1
2
1
2
Cultivation
SSb
PSc
6.6
5.7
5.1
5.3
79
98
70
67
31
45
41
44
120
91
103
127
0.07
0.05
0.06
0.06
0.05
0.05
0.04
0.07
Forage Trt.
Simpled
Blende
5.9
6.4
5.9
4.5
92
84
78
58
36
41
47
38
100
110
127
102
0.06
0.05
0.09
0.04
0.05
0.05
0.06
0.05
f
SEM
0.02
0.03
4
3
2
2
6
4
0.01
0.01
0.003
0.005
Significanceg
Cult.h Foragei
**
NS
NS
**
*
NS
NS
**
**
*
NS
**
**
NS
**
**
NS
NS
NS
*
NS
NS
**
NS
CxFj
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
b
SS = sod-seeded pastures
c
PS = prepared seedbed (clean-tilled) pastures.
d
Simple blend or mono-culture of forage species in pastures (Exp. 1, small grains – rye and oats; Exp. 2,
ryegrass only).
e
f
Blend of forage species in pastures (Exp. 1, small grains plus ryegrass; Exp. 2, oats plus ryegrass).
Standard error of the mean; n = 8.
g
Significance of difference; ** = highly significantly different (P<0.01), * = significantly different (P<0.05),
and NS = non-significant (P>0.05).
h
Pasture establishment method (PS vs. SS).
i
Pasture forage treatment (simple vs. blend).
j
Establishment method by forage treatment interaction.
121
Table 2. Monthly concentrations of trace minerals in annual cool-season pasture forages during the
late fall-winter-spring grazing season in north Florida (ppm of dry matter).
Sampling month
Exp.a
Nov
Dec
Jan
Feb
Mar
Apr
May
SEMb
1
5.8
7.7
8.2
6.1
6.0
6.4
5.5
0.4
2
5.7
4.9
5.1
5.0
5.5
5.3
4.8
0.5
Fe
1
190
126
178
98
75
92
105
13
2
85
83
83
90
82
64
60
12
Zn
1
30
33
41
37
36
41
60
3
2
41
39
42
48
40
42
46
5
Mn
1
82
95
111
106
105
105
125
9
2
78
107
96
91
108
112
124
10
Co
1
-0.05
-0.03
0.02
0.08
0.09
0.03
2
----0.07
0.07
0.12
0.05
Se
1
-0.05
-0.05
0.04
0.06
0.06
0.02
2
----0.07
0.05
0.06
0.01
a
Mineral
Cu
b
Significancec
**
NS
**
**
**
NS
**
**
*
NS
NS
NS
Standard error of the mean; average n = 8 (average n = 3 for Co and Se).
c
Significance due to month within experiment; ** = highly significant (P<0.01), * = significant (P<0.05), and
NS = non-significant (P>0.05).
Table 3. Overall means and ranges of trace mineral concentrations of annual cool-season annual
grass pasture forages from each two-year experiment (ppm, dry matter basis).
Mineral
Cu
Fe
Zn
Mn
Co
Se
a
1S.D.c
0.5
0.9
15
13
4
4
19
9
0.02
0.02
0.01
0.01
Ranged
4.0 to 9.9
4.0 to 9.4
56 to 242
68 to 156
13 to 56
29 to 74
56 to 171
62 to 160
0.02 to 0.10
0.03 to 0.13
0.03 to 0.07
0.04 to 0.08
Requiremente
10
Reportedf
4 to 8
50
101 to 367
30
25 to 30
40
42 to 66
0.10
--
0.10
0.07
Overall mean across all treatments (n = 24; 8 for Co and Se).
One standard deviation.
d
e
Meanb
6.4
5.2
88
68
38
42
105
114
0.06
0.06
0.05
0.06
b
c
Exp.a
1
2
1
2
1
2
1
2
1
2
1
2
Lowest or highest monthly concentration obtained from a treatment within year within experiment (n = 2).
Suggested requirement for growing beef cattle heifers (500 to 900 lb; NRC 2000).
f
Other reported concentrations for rye, oats and ryegrass fresh forage (dry matter basis); data from Ensminger et
al., 1990, and NRC, 2000.
122
Effects of Aluminum (Al) from Water Treatment Residual Applications to Pastures on
Mineral Status of Grazing Cattle and Mineral Concentrations of Forages
Rachel Madison1
Lee McDowell
George O’Connor
Nancy Wilkinson
Paul Davis
Adegbola Adesogan
Tara Felix
Megan Brennan
Al-Water Treatment Residuals applications to pastures in low to moderately high levels, help
alleviate environmental phosphorus contamination.
Summary
Amorphous aluminum (Al) hydroxides applied to
land in the form of water treatment residuals
(Al-WTR) can reduce soluble soil phosphorus
(P) concentrations in soils and thus can reduce
P contamination of the environment. Two
experiments of 145 or 148 d each using 36
grazing Holstein steers were conducted to
determine the effects of Al-WTR pasture
applications on mineral status of cattle and
mineral concentrations of bahiagrass (Paspalum
notatum). Treatments were replicated 3 times
each and were as follows: 1) control- no AlWTR application with steers receiving freechoice mineral supplementation without P, 2)
control with free-choice mineral supplement
plus P, 3) treatment 1 with Al-WTR, and 4)
treatment 2 with Al-WTR. Total application of
Al-WTR over two yr was 169.5 tons dry
weight/ac on the pastures. In general, there
were few treatment effects on weight gains and
mineral concentrations in plasma, liver, bone
and forage mineral concentrations. Most forage
samples were deficient in sodium, copper,
selenium and cobalt and at various collection
dates deficient in calcium, phosphorus, iron and
zinc. The use of Al-WTR applications is an
effective method of reducing P contamination
that does not adversely affect forage or cattle
mineral concentrations.
Introduction
There is an increasing public demand to reduce
the amount of phosphorus (P) transported to
water bodies due to the risk of eutrophication,
mainly from agricultural P-inputs, including the
land application of animal manure. Extensive
efforts have been focused on finding ways to
reduce soluble P in manure-impacted soils.
Aluminum (Al) binds to P and application of Al
could be one potential solution to the problem.
However, application of Al to the land can also
result in ingestion by livestock and potential
harm to animals.
Aluminum water treatment residuals (Al-WTR)
are the by-products of water purification
procedures. They may be one solution to the P
problem, in that the Al in the product will bind
with P, thus preventing leaching into
groundwater. Prior research from Florida has
shown that amending soils with Al-WTR
increases soil retention and reduces leaching of
123
P (O’Connor et al., 2002).
Two experiments were conducted to determine
the effects of pasture application of Al-WTR on
mineral status (primarily P) and performance of
grazing cattle. A second objective was to
evaluate the effects of the applied Al-WTR on
forage mineral concentrations.
separation. Significance was declared at P <
0.05.
Results
In general, differences in animal performance
among treatments were limited throughout the
experiment in both yr. In both experiments,
application of Al-WTR to pastures of grazing
ruminants to control environmental P was not
detrimental to the animal when considering BW
alone.
Procedure
Two experiments were carried out in
consecutive yr, 2005 and 2006 using 36 grazing
Holstein steers for 145 or 148 d respectively.
Aluminum – water treatment residuals (AlWTR) pasture applications were applied over
two yr totaling 169.5 tons dry weight/ac.
Plasma macrominerals (Ca, Mg and P)
concentrations were greater, in general, in
experiment 1. Yet, the microminerals (Al, Cu
and Zn) concentrations were generally greater in
experiment 2. Plasma P concentrations were
greater in experiment 1 than experiment 2 (6.02
vs. 5.18 mg/dL).
Steers were allotted (three/pasture) to one of
twelve 2.0 ac bahiagrass (Paspalum notatum)
pastures on d 0 and provided ad libitum water
and grazing access. Soil series that exist at this
location are Millhopper sand, Bonneau fine
sand, and Gainesville sand.
Experimental
pastures were randomly allotted to one of four
treatments with three replications per treatment.
The Al-WTR product contained 0.30% iron
(Fe), 7.8% Al, 0.11% calcium (Ca), 0.024%
magnesium (Mg), 0.30% P, 0.004% manganese
(Mn), 0.73% sulfur (S), 0.006% copper (Cu),
0.002% zinc (Zn), and approximately 70%
solids. The treatments were 1) control-no AlWTR application with steers receiving
commercial free-choice mineral supplement but
no P, 2) control with free-choice mineral
supplement plus P, 3) treatment 1 with Al-WTR
and 4) treatment 2 with Al-WTR.
In both experiments, P plasma levels were
normal to low, but never reached a level of
deficiency at any collection. Therefore, the Al
in the Al-WTR did not complex with P enough
to cause a deficiency in the cattle during either
experiment. In both experiments, the Al plasma
concentrations were very low (0.02 μg/mL, on
average), indicating that the Al in Al-WTR may
be unavailable to the animal and safe to use on
pastures to reduce the P environmental problem.
In general, there were few treatment effects on
mineral concentrations in liver and bone.
Forage mineral concentrations as affected by AlWTR are presented in Tables 1 and 2.
Throughout the collection periods forage Ca
concentration was below or slightly above the
critical level of 0.35%. Using 0.18% P as a
critical level, both treatment groups produced
adequate forage P concentrations until
August/September for both experiments.
Magnesium, K and Mn forage concentrations
were adequate for both treatments during both
yr.
Weights, blood and liver biopsies were taken at
d 0, 84 and 148 and bone biopsies were obtained
on d 148. Forage samples were taken on d 0 and
approximately every 28 d thereafter for five mo.
Forage samples were analyzed for Al, Ca, Cu,
Fe, potassium (K), Mg, Mn, sodium (Na), P, Zn,
cobalt (Co) molybdenum (Mo) and selenium
(Se).
All forage Na concentrations were below the
critical level of 0.06% during both experiments.
All forage Cu concentrations were below the
critical level of 10 mg/kg in both experiments
and were lower, on average, in experiment 1.
Aluminum concentration were similar in
experiments 1 and 2 and varied by date (P<0.05)
Data were analyzed for treatment effects using
Proc Mixed in SAS (SAS for Windows v9; SAS
Inst., Inc. Cary, NC) for a completely
randomized design with a 2x2 arrangement of
treatments. Contrasts (control vs. Al-WTR, no P
vs. P, and the interaction) were used for mean
124
in all but treatment 1 of experiment 2. Zinc
concentrations also varied by date in both
experiments and were similar between
treatments (P>0.05). Most Zn concentrations
were below the critical level of 30 mg/kg in both
experiments.
Only a limited number of samples were analyzed
for Co, Mo and Se. Forage Mo concentrations
means were not variable between treatments,
and generally low throughout all sampling
periods. Forage Mo concentrations ranged from
0.09 to 2.45 mg/kg and averaged 0.69 ± 0.60
mg/kg. Over 99% of all Co samples taken were
below the critical concentration of 0.1 mg/kg.
Forage Se concentrations in this study were
extremely deficient and were all less than the
requirement of 0.1 mg/kg. Previous Florida
studies have shown the majority of forages to be
deficient in Na, P, Ca, Cu, Co, Se and Zn
(McDowell and Arthington, 2005).
Literature Cited
McDowell and Arthington. 2005. Minerals for Grazing Ruinants in Tropical Regions, IFAS/Animal
Sciences, Gainesville, FL.
O’Connor, et al. 2002. Soil Crop Sci. Soc. Florida Proc. 61:67.
1
Rachel Madison, Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist;
Paul Davis, Former Graduate Student; Adegbola Adesogan, Associate Professor; Tara Felix, Former
Graduate Student, UF/IFAS, Department of Animal Sciences, Gainesville, FL; George O’Connor,
Professor, UF/IFAS, Department of Soil and Water Science, Gainesville, FL; Megan Brennan, Assistant
Professor, UF/IFAS, Department of Statistics, Gainesville, FL.
125
Forage minerals (dry basis) as affected by water treatment residuals (Experiment 1) 1-4
Trt5 May
Jul
Aug
Sept
Oct
Nov
Dec
Means6
a
bc
c
c
bc
b
bc
Ca, %
1
0.38
0.30
0.27
0.27
0.28
0.32
0.31
0.30
2
0.33bc
0.27bcd
0.31bcd 0.27bcd 0.26d
0.42a
0.35b
0.32
SD 0.04
0.20
0.03
0.00
0.10
0.07
0.03
0.01
a
b
bc
cd
bc
a
d
K, %
1
1.38
1.43
1.33
0.82
1.09
2.14
0.43
1.23
2
1.51b
1.36bc
1.18bc
1.02c
1.09bc
2.09a
0.44d
1.24
SD 0.09
0.05
0.11
0.14
0.00
0.04
0.01
0.01
Mg, %
1
0.18ab
0.19a
0.16b
0.16b
0.18ab
0.16b
0.13c
0.17
bc
a
ab
c
bc
ab
c
2
0.17
0.20
0.19
0.15
0.17
0.19
0.15
0.17
SD 0.01
0.10
0.02
0.01
0.01
0.02
0.01
0.00
abc
abc
abc
abc
a
a
c
Na, %
1
0.02
0.02
0.02
0.02
0.03
0.03
0.01
0.02
2
0.02b
0.02b
0.02b
0.01b
0.02b
0.04a
0.01b
0.02
SD 0.00
0.00
0.00
0.01
0.01
0.01
0.00
0.00
P, %
1
0.23a
0.23a
0.15b
0.14b
0.14b
0.14b
0.06c
0.16
a
a
ab
b
b
b
c
2
0.22
0.21
0.17
0.12
0.14
0.15
0.06
0.15
SD 0.01
0.01
0.01
0.01
0.00
0.01
0.00
0.01
b
a
c
b
c
bc
c
Al, mg/kg
1
35.0
65.3
17.3
36.1
18.7
26.2
17.7
30.9
2
25.1bcd
31.9ab
15.8e
28.9bc
39.2a
37.4a
20.1cde 28.3
SD 7.0
23.6
1.06
5.09
14.5
7.92
1.70
1.84
Cu, mg/kg
1
9.69a
8.17bc
8.75ab
5.76d
6.18d
6.87cd 7.95bc
7.66
2
8.41a
8.23a
7.52a
5.32b
5.55b
8.48a
8.29a
7.39
SD 0.91
0.04
0.87
0.31
0.45
1.14
0.24
0.19
a
a
b
b
b
a
b
Fe, mg/kg
1
66.3
59.1
33.3
34.3
35.4
54.9
42.1
44.5
2
43.9c
43.1bc
33.7c
36.7c
36.4c
66.6a
52.4bc
44.7
SD 15.8
11.3
0.28
1.70
0.71
8.27
7.28
0.14
b
ab
c
c
ab
a
a
Mn, mg/kg 1
78.3
83.8
60.5
56.5
90.7
96.1
95.1
80.1
2
48.9c
49.7c
48.6c
48.3c
63.2b
70.0ab 79.6a
58.3
SD 20.8
24.1
8.41
5.80
19.4
18.5
11.0
15.4
a
b
b
bc
cd
cd
d
Zn, mg/kg
1
34.4
28.8
28.7
25.9
23.3
23.0
18.6
26.1
2
43.9bc
43.1bc
33.7c
36.7c
36.4c
66.6a
52.4b
44.7
SD 6.72
10.1
3.54
7.64
9.26
30.8
23.9
13.2
a-e
Means with same letters within rows are not different (P<0.05).
1
Water treatment residual contained 0.30% Fe, 7.8% Al, 0.11% Ca, 0.024% Mg, 0.30% P, 0.004%
Mn, 0.73% S, 0.006% Cu and 0.002% Zn.
2
Critical concentrations are as follows: Ca, 0.35%; P, 0.18%; Mg, 0.10%; K, 0.60%; Na, 0.06%;
Cu, 10.0 mg/kg; Fe, 50.0 mg/kg; Mn, 20.0 mg/kg; Zn, 30.0 mg/kg (NRC, 1986; McDowell and
Arthington, 2005).
3
Means represent 12 samples per month per treatment.
4
In November for forage Ca, treatment with Al-WTR was lower (<0.05) than the control. In July
for forage Al, control treatment was lower (P<0.05) than treatment with Al-WTR.
5
Treatments were as follows: 1) Al-WTR; 2) Control- no Al-WTR.
6
Means of seven months of sampling
7
SD = standard deviation
Table 1.
126
SD7
0.04
0.06
0.50
0.47
0.02
0.02
0.01
0.01
0.05
0.05
15.8
8.00
1.31
1.27
12.48
10.66
14.89
11.78
4.73
10.66
Forage minerals (dry basis) as affected by water treatment residuals (Experiment 2) 1-4
Trt5 May
Jun
Jul
Aug
Sep
Oct
Means6 SD7
Ca, %
1
0.42a
0.32c
0.38ab
0.38ab
0.33c
0.37bc 0.37
0.04
a
c
bc
ab
a
2
0.37
0.29
0.31
0.36
0.39
0.35ab 0.33
0.05
SD 0.04
0.20
0.05
0.01
0.04
0.01
0.03
K, %
1
1.49a
1.39ab
1.33b
0.31bc
1.23bc
1.21c
1.33
0.10
a
b
b
a
a
a
2
1.42
1.96
1.14
1.40
1.58
1.45
1.33
0.23
SD 0.05
0.30
0.13
0.06
0.25
0.17
0.00
Mg, %
1
0.18cd
0.20ab
0.19bc
0.21a
0.17d
0.19bc 0.19
0.01
b
a
b
ab
ab
2
0.18
0.20
0.18
0.19
0.19
0.18b
0.19
0.01
SD 0.00
0.00
0.01
0.01
0.01
0.01
0.00
Na, %
1
0.02 a
0.01b
0.02 a
0.02 a
0.02 a
0.02 a
0.02
0.00
b
b
a
b
b
b
2
0.02
0.02
0.01
0.02
0.02
0.02
0.02
0.00
SD 0.00
0.01
0.01
0.00
0.00
0.00
0.00
P, %
1
0.02
0.19
0.19
0.19
0.15
0.17
0.18
0.19
2
0.21a
0.21a
0.19ab
0.19ab
0.18ab
0.17b
0.19
0.02
SD 0.01
0.01
0.00
0.00
0.02
0.00
0.01
Al, mg/kg
1
23.4cd
24.7cd
26.3bc
21.3d
33.7a
30.3ab 26.6
4.61
2
26.2cd
30.8bc
23.2d
27.5cd
40.5a
37.7ab 31.0
6.80
SD 1.98
4.31
2.19
4.38
4.81
5.23
3.11
a
b
b
b
b
c
Cu, mg/kg
1
9.54
8.33
8.67
8.41
8.78
7.63
8.54
0.62
2
9.16a
9.27a
8.13bc
7.47c
8.39b
7.88c
8.35
0.71
SD 0.27
0.66
0.38
0.66
0.28
0.18
0.13
Fe, mg/kg
1
50.8ab
47.2b
54.5a
55.2a
48.4b
39.5c
49.3
5.75
a
a
b
b
b
2
58.5
53.8
44.8
42.2
43.8
41.0b
47.4
7.10
SD 5.44
4.67
6.86
9.19
3.25
1.06
1.34
a
a
a
a
a
Mn, mg/kg 1
92.0
69.1
84.7
64.8
88.2
142.4 90.2
27.76
2
55.7bc
58.9bc
40.6c
74.1b
90.1ab
93.3a
68.7
20.77
SD 25.7
7.21
31.2
6.58
1.34
34.7
15.2
Zn, mg/kg
1
37.4ab
26.3cd
31.5bc
19.8d
20.5cd
44.4a
30.0
9.72
b
b
bc
ab
c
2
25.5
24.9
21.0
29.1
15.7
32.4a
24.8
5.90
SD 8.41
1.00
7.42
6.58
3.39
8.49
3.68
a-d
Means with same letter within rows are not different (P<0.05).
1
Water treatment residual contained 0.30% Fe, 7.8% Al, 0.11% Ca, 0.024% Mg, 0.30% P, 0.004%
Mn, 0.73% S, 0.006% Cu and 0.002% Zn.
2
Critical concentrations are as follows: Ca, 0.35%; P, 0.18%; Mg, 0.10%; K, 0.60%; Na, 0.06%;
Cu, 10.0 mg/kg; Fe, 50.0 mg/kg; Mn, 20.0 mg/kg; Zn, 30.0 mg/kg (NRC, 1986; McDowell and
Arthington, 2005).
3
Means represent 12 samples per month per treatment.
4
In November for forage Ca, treatment with Al-WTR was lower (<0.05) than the control. In July
for forage Al, control treatment was lower (P<0.05) than treatment with Al-WTR.
5
Treatments were as follows: 1) Al-WTR; 2) Control- no Al-WTR.
6
Means of seven months of sampling
7
SD = standard deviation
Table 2.
127
128
Methods of Selenium Supplementation to Beef Cows on Blood, Liver and
Milk Selenium Concentrations
Paul Davis1
Lee McDowell
Claus Buergelt
Nancy Wilkinson
Rachel Van Alstyne
Tim Marshall
Richard Weldon
Organic selenium was superior to other forms of supplementation in maintaining blood and milk
selenium adequate for nursing calves.
Summary
In a 365-d study, the effects of form and method
of selenium (Se) supplementation on blood, milk,
and tissue Se in grazing beef cows were
evaluated. Forty-three Angus cows (115-130 d
gestation) were randomly assigned to 1 of 5
treatments and received either no Se
supplementation (control), one 9-mL barium
selenate injection at the initiation of the study,
one 5-mL sodium selenite injection + 68 IU
vitamin E at the initiation of the study and every
4 mo thereafter, or free-choice minerals
containing 26 mg/kg Se as sodium selenite or Se
yeast (Sel-Plex). Cows receiving Se in freechoice minerals were heavier and had a greater
increase (P < 0.05) in bodyweight at d 365 than
cows receiving all other treatments. Liver Se at
d 365 was adequate (> 1,200 µg/kg) and greater
(P < 0.05) in Se yeast-treated cows than in all
other treatments. Cows receiving injectable
selenate also had adequate liver Se
concentrations that were greater (P < 0.05) than
the inadequate concentrations from control,
free-choice selenite or injectable selenite. At
205 d postpartum, cows receiving injectable
selenate and both free-choice treatments were
inadequate whole blood Se concentrations.
Cows receiving Se yeast produced colostrums
with greater (P < 0.05) Se concentration than
all others. At weaning (205 d postpartum), cows
receiving Se yeast had at least 2-fold greater (P
< 0.05) milk Se than cows on other treatments.
Selenium supplementation with organic or
inorganic Se via free-choice minerals or
injectable selenate maintained adequate Se
concentrations in whole blood, plasma, and
liver. Inorganic Se was limited in its ability to
increase milk Se, whereas Se yeast increased
milk Se at parturition and at weaning.
Introduction
Many areas of the United States have soils that
are deficient in selenium (Se) (McDowell, 2003)
and may produce forages and grains that do not
provide adequate Se to livestock. Almost all
regions of Florida are severely deficient in Se
(McDowell and Arthington, 2003). Selenium
deficient brood cows may give birth to calves
which are stillborn, premature, weak, or afflicted
with nutritional muscular degeneration (Corah
and Ives, 1991). Likewise, even with adequate
blood Se at birth, calves suckling Se deficient
dams are susceptible to becoming Se deficient
(Pehrson et al., 1999; Gunter et al., 2003). The
objective of this experiment was to evaluate and
129
compare effects of form and method of Se
supplementation on blood, liver, and milk Se
concentrations in beef cows.
day on BW, whole blood Se, milk Se, plasma
Se, and liver Se as repeated measures.
Results
Selenium concentration of pasture and hay for
all groups averaged 0.071 ± 0.014 and 0.045
mg/kg (DM basis), respectively.
Mineral
consumptions, total amount of Se administered,
and total vitamin E supplemented are
summarized in Table 1. Both free-choice
treatment groups were similar and had a greater
increase in BW (P < 0.05) than did control and
the injectable Se treated groups.
Procedure
Animals were housed at the University of
Florida Boston Farm-Santa Fe Beef Unit located
in Northern Alachua County, Florida. On
August 6, 2002, 43 Angus cows, aged two to
three yr, (mean age = 2.67 yr) were palpated to
diagnose pregnancy and estimate days in
gestation. All cows were determined pregnant
and gestation estimates ranged from 115 to 130
d. Cows were weighed (average initial body
weitht (BW) = 919 ± 101 lb), stratified by age
and assigned to one of five treatment groups for
a 365-d study. The 5 treatments were 1) no Se
supplementation (control), 2) one subcutaneous
injection of 9 mL (50 mg Se/mL) of barium
selenate (Deposel Multidose®; Novartis New
Zealand, Ltd., Auckland, NZ) at the initiation of
the experiment, 3) three subcutaneous injections
of 5 mL (5 mg Se/mL) of sodium selenite with
68 IU vitamin E/mL as DL-alpha tocopheryl
acetate (Mu-Se®; Schering-Plough Animal
Health, Union, NJ), one at the initiation of the
experiment and one every four mo thereafter, 4)
free-choice access to a mineral mixture
containing 26 mg/kg Se as sodium selenite
(Southeastern Minerals, Inc., Bainbridge, GA),
or 5) free-choice access to a mineral mixture
containing 26 mg/kg Se as Se yeast (Sel-Plex®;
Alltech, Inc, Nicholasville, KY). All cows
grazed bahiagrass (Paspalum notatum) pastures
and were supplemented with bahiagrass hay, ad
libitum molasses-based liquid supplement, and
whole cottonseed and pelleted citrus pulp at
rates of 1.5 and 4.0 lb/d per cow, respectively,
from November 2002 through March 2003.
During the experiment pasture, blood, liver,
colostrum and later produced milk were
analyzed for Se by a fluorometric procedure.
Cow whole blood Se concentrations at intervals
postpartum are summarized in Table 2.
Significant effects of treatment (P < 0.001), day
(P < 0.001), and treatment × day (P = 0.013)
were observed. At parturition, whole blood Se
concentrations from cows receiving Deposel or
Sel-Plex were greater (P < 0.05) than whole
blood Se from controls and cows receiving MuSe or free-choice selenite.
At calving, cows receiving Se via Deposel or
Sel-Plex had greater whole (P<0.05) blood Se
than did cows receiving no Se, Mu-Se, or
selenite in free-choice minerals. Whole blood
Se measured at 30 and 90 d postpartum followed
a similar pattern, with respect to treatment, to
whole blood Se at calving. Deposel and SelPlex produced similar and consistently greater
whole blood Se than sodium selenite or no Se
supplementation.
From d 90 to d 205
postpartum, whole blood Se decreased in
controls and cows receiving Mu-Se, and both
were below the adequate whole blood Se level
(> 100µg/L). Cows receiving Se from Deposel
or either free-choice mineral mix maintained
blood Se above the adequate level from
parturition to 205 d postpartum. At d 205
postpartum, 100% of controls and 89% of cows
receiving Mu-Se had whole blood Se below the
adequate level.
Effects of treatment on change in BW were
analyzed using PROC MIXED in SAS (SAS for
Windows 8e; SAS Inst., Inc., Cary, NC) in a
completely randomized design with a diagonal
covariance structure. The PROC MIXED of
SAS was also used to analyze effects of
treatment, day, and the interaction of treatment ×
Effects of treatment and d (P < 0.001) were
observed in Se concentration of milk collected at
the same postpartum intervals as whole blood
(Table 3). Cows receiving Sel-Plex had greater
(P < 0.05) Se concentrations in postsuckled
130
colostrum than did cows receiving all other
treatments. Colostrum Se was similar (P > 0.54)
from control, Deposel, Mu-Se and free-choice
selenite treated cows. At 90 d postpartum, no
differences or tendencies were observed in milk
Se among treatment groups (P > 0.28).
Selenium in milk collected at 205 d postpartum,
was similar (P > 0.50) among control, Mu-Se,
Deposel, and free-choice selenite treatments.
Cows receiving Sel-Plex produced greater (P <
0.01) milk Se than cows receiving any other
form of Se supplementation. Milk Se from all
treatment groups decreased quadratically (P <
0.001) from parturition to 205 d postpartum.
selenite were similar, (P = 0.21) and both were
greater (P < 0.05) than those from controls and
cows receiving Mu-Se. At the end of this study,
liver Se had increased (P < 0.001) in cows
receiving Sel-Plex. Cows receiving Mu-Se had
decreased (P <0.01) liver Se, which tended to
decrease (P = 0.07) in controls. Liver Se
remained unchanged (P = 0.48; 0.73) in cows
receiving Deposel and free-choice mineral with
sodium selenite, respectively. Liver and plasma
Se concentrations were highly correlated (P <
0.001; r = 0.71). In spite of the high degree of
correlation, the authors suggest that liver Se
continue to be used where possible to help
validate plasma, whole blood Se concentrations,
or both.
Plasma Se concentrations were evaluated at d 0
and at d 365. Plasma Se concentrations in SelPlex treated cows were greater (P < 0.005) than
from cows receiving any other treatment. After
1 yr, only cows receiving Sel-Plex had increased
(P < 0.001) plasma Se, data not shown.
Sel-Plex supplemented cows had greater Se
concentration in liver at the end of our study
than did cows receiving any other treatment.
Sel-Plex produced liver Se concentrations up to
3-fold greater than Mu-Se. At the termination of
the experiment, 100% of cows supplemented
with selenite, free-choice or injectable, and cows
receiving no supplemental Se had plasma Se
concentrations below the critical level of > 70
µg/L.
Liver from biopsies at d 0 and d 365 was
evaluated for Se concentration (Table 4). Liver
Se (946 to 1136 µg/kg) did not differ among
treatment groups at d 0 (P > 0.31). However, at
d 365, liver Se from Sel-Plex treated animals
was greater (P < 0.02) than from animals on all
other treatments. Liver Se concentrations from
cows receiving Se from Deposel or free-choice
Literature Cited
Corah and Ives. 1991. Vet Clin. North Am. Food Anim. Pract. 7:41.
Gunter et al. 2003. J. Anim. Sci. 81:856.
McDowell. 2003. Minerals in Animal and Human Nutrition, Elsevier Science, Amsterdam.
McDowell and Arthington. 2005. Minerals for Grazing Ruminants in Tropical Regions, Dept. Animal
Sci., Gainesville.
Pehrson et al. 1999. J. Anim. Sci. 77:3371.
Acknowledgments
Special thanks go to Southeastern Minerals Inc., Flint River Mills, U.S. Sugar Corp., and Alltech Inc. for
donation of products or services to aid in this research, to E.Y. Matsuda-Fugisaki for assistance in
analyses of blood and tissues, and to Steve Chandler and Bert Faircloth for animal care and feeding.
1
Paul Davis, Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist; Tim
Marshall, Professor; Rachel Van Alstyne, Former Graduate Student; UF/IFAS, Department of Animal
Sciences, Gainesville, FL; Claus Buergelt, Professor, College of Veterinary Medicine, Gainesville, FL;
Richard Weldon, Professor, Food and Resource Economics, Gainesville, FL.
131
Table 1. Frequency, daily amount, and total of amount of supplemental Se administered to cows
Source of supplemental Se
No Se supplementation
Selenium
supplementation
interval, d
—1
Avg Se
supplementation,
mg Se/cow per d
—1
Total Se
supplementation,
mg
—1
Total Vitamin E
supplementation,
IU
235
Barium selenate2 (Deposel)
365
1.23
450
235
3
Sodium selenite (Mu-Se)
125
0.21
75
1255
Free-choice mineral mix4 (sodium
6
1
1.08
393
158
selenite)
Free-choice mineral mix5 (Sel-Plex)
16
2.22
811
326
1
Cows received no Se supplementation or injectable Se had free-choice access to and consumed the basal free-choice mineral
mix (no Se) at an average of 62.2 g/d per cow.
2
Cows received a s.c injection of 9 mL Deposel at d 0.
3
Cows received a s.c. injection of 5 mL Mu-Se every four mo beginning at d 0.
Cows had continuous access to free-choice mineral mix containing 26 mg Se/kg as sodium selenite and consumed mineral
mix at an average of 41.5 g/d per cow.
5
Cows had continuous access to free-choice mineral mix containing 26 mg Se/kg as Se yeast and consumed mineral mix at an
average of 85.5 g/d/ per cow.
6
Access to free-choice minerals containing Se was continuous throughout the study.
4
Table 2. Whole blood Se concentrations of cows receiving different sources and forms of Se supplementation at
various days postpartum1
0
Days postpartum
30
90
Whole blood Se, µg/L
162a ± 15
121a ± 15
bc
207 ± 12
166bc ± 12
ac
178 ± 12
127ad ± 12
ac
184 ± 13
140cd ± 13
b
241 ± 12
185b ± 12
205
Source of Se supplementation
Control (No Se)
143a ± 15
74a ± 15
2
b
Barium Selenate (Deposel)
235 ± 12
156b ± 12
3
a
Sodium Selenite (Mu-Se)
173 ± 13
89a ± 12
4
a
Free Choice Mineral Mix ( Sodium selenite)
159 ± 12
155b ± 13
5
b
Free Choice Mineral Mix (Sel-Plex)
216 ± 12
198c ± 12
a-d
Means within columns lacking a common superscript differ (P < 0.05).
1
Data represent least squares means ± SE; n = 41/d; adequate Se level in whole blood is > 100 μg/L.
2
Cows received a s.c. injection of 9 mL Deposel at d 0.
3
4
Cows consumed free-choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow
beginning at d 0.
5
Cows consumed free-choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.
132
Table 3. Milk Se concentrations of cows receiving different sources and forms of Se supplementation at various days
postpartum1
0
Days postpartum
30
90
Milk Se, µg/L
14 ± 7
6±7
15 ± 6
15 ± 6
13 ± 6
6±6
26 ± 6
16 ± 6
27 ± 6
15 ± 6
205
Source of Se supplementation
Control (No Se)
39a ± 7
15a ± 7
2
a
34 ± 6
21a ± 6
3
a
35 ± 6
16a ± 6
4
a
Free Choice Mineral Mix ( Sodium selenite)
39 ± 7
15a ± 7
5
b
71 ± 6
42b ± 6
a.b
Means within columns with different superscripts differ (P < 0.05).
1
Data represent least squares means ± SE; n = 41 for each sample day.
2
3
4
Cows consumed free-choice mineral mix containing 26 mg/kg Se as sodium selenite at an average of 41.5 g/d per cow
beginning at d 0.
5
Cows consumed free-choice mineral mix containing 26 mg/kg Se as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.
Table 4. Liver Se concentration (DM basis) at d 0 and d 365 of beef cows that received different sources and forms of
Se supplementation1
d0
d 365
Source of Se Supplementation
Liver Se, µg/kg
Liver Se, µg/kg
Control (No Se)
973 ± 129
642 ± 129a
2
1136 ± 105
1240 ± 105b
3
946 ± 105
537 ± 105a
4
Free Choice Mineral Mix (Sodium selenite)
1089 ± 105
1046 ± 105b
5
1011 ± 105
1604 ± 105c
a-c
Means within columns lacking a common superscript differ (P < 0.05).
1
Data represent least squares means ± SE; n = 42 and 41 for d 0 and d 365, respectively; adequate Se concentration in
liver is > 1,200 μg/kg.
2
3
4
Cows consumed free-choice mineral mix containing 26 mg Se/kg as sodium selenite at an average of 41.5 g/d per
cow beginning at d 0.
5
Cows consumed free-choice mineral mix containing 26 mg Se/kg as Se yeast at an average of 85.5 g/d per cow
beginning at d 0.
133
134
Comparing Tolerance of Selenium (Se) as Sodium Selenite or Se Yeast on
Blood and Tissue Se Concentrations of Ruminants
Paul Davis1
Lee McDowell
Nancy Wilkinson
Claus Buergelt
Rachel Van Alstyne
Richard Weldon
Tim Marshall
Eric Matsuda-Fugisaki
Selenium, whether in organic or inorganic forms, can be fed as high as 40 mg/kg for up to 60 wk
without inducing selenium toxicosis. Increasing dietary selenium level regardless of source is an
effective means of increasing selenium in blood and tissues.
Summary
The objective of this 60 wk study was to
determine the maximum tolerable level of
selenium (Se) by feeding Se as sodium selenite
or Se yeast at high dietary concentrations to
wether sheep.
Twenty-eight, two-year-old,
Rambouillet-crossbred wethers (137.1 ± 18.7 lb
initial body weight) were utilized in a 2 × 4
factorial arrangement with 0.2, 20, 30 and 40
mg/kg dietary Se (as-fed) as either selenite or
yeast Se added to a corn-soybean meal basal
diet. Average body weight decreased linearly (P
< 0.10) as dietary Se level increased, though
most wethers gained body weight. Serum Se,
whole blood Se, and wool Se concentrations
from wethers receiving organic Se were greater
(P < 0.01) than those from wethers receiving
inorganic Se. Selenium concentrations in brain,
diaphragm, heart, hoof, kidney, liver and loin
muscle were affected (P < 0.05) by dietary Se
concentration, with higher Se concentrations
generally observed in tissues from wethers
receiving organic Se. Though Se concentrations
in serum, blood, wool, and major organs at most
times exceeded concentrations previously
reported in livestock suffering from Se toxicosis,
a pattern of clinical signs of Se toxicosis was not
observed in this experiment. Histopathological,
microscopic evaluation of liver, kidney,
diaphragm, heart, and psoas major muscle did
not reveal definitive evidence of Se toxicosis in
wethers on any dietary Se treatment. Wethers
under our experimental conditions tolerated up
to 40 mg/kg dietary Se for 60 wk, though
differences in Se source were observed.
Contrary to previous thought, the range between
optimal and toxic dietary levels is not narrow.
Introduction
Current estimates put the maximum tolerable
level of Se at 5 mg/kg for the major livestock
species (NRC, 2005) and no differentiation
exists for tolerable levels between ruminants and
monogastrics. However, Wright and Bell (1966)
reported that swine retained 77% and sheep
retained 29% of an oral dose of inorganic Se.
The NRC makes no distinction between
inorganic and organic (e.g., Se yeast or selenomethionine) forms of Se.
Kim and Mahan
(2001) reported more accumulation of Se in the
plasma and tissues of swine fed high dietary
levels of Se as Se yeast compared to the same Se
levels as sodium selenite. They concluded that
greater than 5 mg/kg dietary Se, regardless of
source, did produce signs of Se toxicity in
growing swine. Based on these findings and the
increasing use of organic forms of Se for
supplementation to livestock, an experiment was
conducted to determine the maximum tolerable
135
level of Se by feeding Se as sodium selenite or
Se yeast at high dietary levels to ruminants.
was observed at wk 36 (Table 1). Over the
entire trial, serum Se increased quadratically (P
< 0.05) as dietary Se level increased. Wethers
receiving organic Se had greater (P < 0.001)
serum Se than did selenite treated wethers
throughout the study. Cristaldi et al. (2004)
reported a linear increase in serum Se as dietary
Se was increased, however those authors used a
maximum level of 10 mg/kg dietary Se as
selenite. Our data show that at most collections
organic Se produced serum Se of more than
double the concentration produced by feeding
selenite Se at the same level.
Procedure
This experiment was conducted from June 4,
2002 to July 29, 2003 at the University of
Florida Sheep Nutrition Unit located in
southwestern Alachua County, FL. Twentyeight, two-year-old, Rambouillet-crossbred
wethers were weighed (137.1 ± 18.7 lb) and
randomly assigned to one of eight dietary
treatments for a 60 wk study. Dietary treatments
were arranged as a 2 × 4 factorial with 0.2, 20,
30 and 40 mg/kg Se (as-fed) as four dietary
levels and Se yeast (Sel-Plex; Alltech, Inc.) and
sodium selenite (Southeastern Minerals, Inc.) as
two Se sources added to a corn-soybean mealcottonseed hull basal diet. Blood was collected
periodically and samples of brain, diaphragm,
heart, hoof tip, kidney, liver, and psoas major
muscle were collected at slaughter for Se
analysis. At termination, blood was again
collected and analyzed for albumin and enzymes
suggestive of tissue breakdown. Analyses were
carried out using standardized procedures.
Selenium concentration in new growth wool was
measured at wk 12, 24, 36, 48 and 60 (Table 2).
Dietary Se concentration, Se source, time,
dietary Se concentration × Se source, and dietary
Se source × time affected (P < 0.05) wool Se.
Wool Se ranged from 1.19 to 39.09 mg/kg and
increased linearly (P < 0.001) as dietary Se
increased. Wool Se from wethers receiving
organic Se was often more than three-fold
greater (P < 0.001) than from wethers receiving
selenite Se at the same dietary concentration.
Wool Se concentrations in the present study
were more than ten-fold higher than
concentrations of 2 to 2.5 mg/kg in wool from
wethers fed up to 10 mg/kg dietary Se as selenite
(Cristaldi et al., 2004), but never exceeded 40
mg/kg which is less than 45 mg/kg which was
described as the Se concentration in hair of
animals suffering from alkali disease (NAS,
1971).
Brain, diaphragm, heart, hoof tip, kidney, liver,
and psoas major Se data were analyzed for
effects of treatment using PROC GLM in SAS
(SAS for Windows 8e; SAS Inst., Inc., Cary,
NC) in a 2 × 4 factorial arrangement. PROC
MIXED was used to analyze effects of
treatment, time, and the interaction of treatment
× time on body weight, serum Se, whole blood
Se, and wool Se as repeated measures with a
spatial power covariance structure with respect
to day and a subplot of animal nested within
treatment.
Selenium concentrations, on a dry matter basis,
were greatest in liver followed by kidney, heart,
hoof, brain, loin, and diaphragm (Table 3).
Brain Se concentrations ranged from 1.28 to
32.3 mg/kg and brain Se concentrations from
wethers receiving organic Se were greater (P <
0.001) than brain Se from wethers receiving
selenite Se. These results suggest that Se does
cross the blood-brain barrier and that brain Se is
influenced by dietary Se source. Diaphragm Se
concentration ranged from 0.82 to 26.34 mg/kg
and tended to increase linearly (P = 0.089) as
dietary Se increased.
Diaphragm Se
concentration was greater (P < 0.001) in wethers
receiving organic Se than from wethers
receiving selenite Se. Heart Se concentration
Results
Wether body weight was affected by dietary Se
level (P < 0.05). Body weights of wethers
receiving 30 or 40 mg/kg dietary Se as Se yeast
decreased from wk 0 to wk 60, whereas wethers
receiving all other dietary Se treatments gained
weight from wk 0 to wk 60.
Serum Se concentrations measured at wk 12, 24,
48 and 60 ranged from 110 to 3,922 µg/L and
increased linearly (P < 0.05) as dietary Se level
increased, while a quadratic response (P < 0.05)
136
ranged from 1.59 to 33.93 mg/kg and, like brain
and diaphragm Se was greater (P < 0.001) in
wethers receiving organic Se than from wethers
receiving selenite Se. Selenium concentrations
in the hoof tip increased linearly as dietary Se
concentration increased (P < 0.05), with wethers
receiving organic Se tending (P = 0.07) to be
greater than those receiving inorganic Se.
Kidney Se concentration tended (P = 0.07) to
respond linearly to increased dietary Se
concentration and ranged from 8.43 to 77.61
mg/kg. Kidney Se concentrations from wethers
receiving organic Se were greater (P < 0.01)
than from wethers receiving selenite Se.
Most of the heart, diaphragm, loin, liver, and
kidney tissues subjected to histopathological
evaluation were free from pathological changes.
No pattern associating abnormal pathology to
either dietary Se level or source could be
established.
Concentrations of albumin and activities of 5
enzymes associated with tissue damage in serum
collected at the termination of the experiment
were, in general, within or below the normal
range for adult sheep. In instances of Se
toxicosis, the activities of these enzymes would
have been increased due to tissue necrosis. The
lack of elevated enzymes, which are suggestive
of tissue necrosis, further indicates that the
wethers on our study were not suffering from Se
toxicosis.
Selenium concentrations in liver from wethers
receiving organic Se were not different (P
=0.34) than liver Se concentrations from wethers
receiving selenite Se. Selenium concentrations
in the loin muscle (psoas major), which is often
consumed ranged from 0.71 to 26.87 mg/kg and
tended (P = 0.12) to increase linearly as dietary
Se concentration was increased. Organic Se was
more effective (P < 0.001) at increasing Se
concentrations in edible tissue than was selenite
Se. As daily intake of Se by humans declines in
some parts of the world, increasing the Se
content of foods for human consumption by
manipulating source and level of Se
supplementation to livestock is now of interest
to food scientists.
The current estimate of the maximum tolerable
level of selenium in ruminants (5 mg/kg diet;
NRC, 2005) seems to be grossly underestimated.
Selenium, whether in organic or inorganic form,
can be fed as high as 40 mg/kg for up to 60 wks
without inducing Se toxicosis.
Literature Cited
Cristaldi et al., 2005. Small Rumin. Res. 56:205.
Kim and Mahan. 2001. J. Anim. Sci. 79:942.
National Academy of Science. 1971. Selenium in Nutrition. National Academy of Science, USA,
Washington, DC.
NRC, 2005. Mineral Tolerance of Domestic Animals. National Academy Press, Washington, DC.
1
Paul Davis, Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist; Rachel Van
Alstyne, Former Graduate Student; Tim Marshall, Professor; UF/IFAS, Department of Animal Sciences,
Gainesville, FL; Claus Buergelt, Professor, College of Veterinary Medicine, UF, Gainesville, FL; Richard
Weldon, Professor, Food and Resource Economics, UF, Gainesville, FL; Eric Matsuda-Fugisaki, Visiting
Researcher, Matsuda, Presidente Bernardes-S.P., Brazil.
137
Table 1. Serum Se concentrations of wethers fed four dietary levels of Se as sodium selenite or Se yeasta
————————————Se source————————————
–———Sodium selenite———–
–————Se yeast————–
—————————Dietary Se level, mg/kg—————————
Week
0.2
20
30
40
0.2
20
30
40
——————————Serum Se, µg/L———————————
12
157
548
788
1,000
412
2,583
3,210
2,458
24
130
1,683
1,487
1,724
354
2,639
3,922
1,585
36
444
851
960
1,083
540
3,283
2,086
1,409
48
110
822
1,219
1,496
292
2,428
2,076
1,831
60
119
610
886
1,250
424
1,699
2,712
2,549
Average
192
903
1,068
1,311
404
2,526
2,801
1,966
a
Data represent least squares means and pooled standard error (SE).
b
Dietary Se level response (P < 0.05).
c
Selenium source response (P < 0.05).
d
Dietary Se level × Se source interaction (P < 0.05).
e
Dietary Se level linear response (P < 0.05).
f
Dietary Se level quadratic response (P < 0.05).
SE
249bcde
826be
250bcdf
253bce
331bce
395bcdf
Table 2. Wool Se concentrations of wethers fed four dietary levels of Se as sodium selenite or Se yeasta
————————————Se source————————————
–————Se yeast————–
Week
0.2
20
30
40
0.2
20
30
40
——————————Wool Se, mg/kg———————————
12
1.37
3.27
6.69
4.15
3.78
12.67
21.09
24.26
24
1.47
3.57
5.72
11.92
7.04
31.58
35.69
37.30
36
1.68
6.02
9.85
10.85
5.70
18.99
22.79
21.29
48
1.19
3.15
5.64
7.23
6.39
24.81
39.09
29.65
60
1.29
3.90
5.01
6.23
4.38
23.22
25.65
25.99
Average
1.40
3.98
6.58
8.08
5.46
22.25
28.87
27.70
a
b
c
d
e
f
Time response (P < 0.05).
g
Time × Se source interaction (P < 0.05).
138
SE
3.80bce
2.87bcd
4.72ce
2.22bcd
2.01bcd
3.38bcdefg
Table 3. Effects of four dietary levels of Se as sodium selenite or Se yeast on tissue Se of wethersa
————————————Se source————————————
–————Se yeast————–
Tissue
0.2
20
30
40
0.2
20
30
40
—————————Se concentration, mg/kg——————————
Brain
1.28
4.22
4.74
6.87
6.12
21.90
32.30
18.71
Diaphragm
0.82
4.74
3.33
7.81
5.28
10.30
26.34
20.71
Heart
1.59
3.80
5.13
6.23
6.35
23.77
28.71
33.93
Hoof
3.44
8.79
9.68
13.78
6.26
12.53
29.20
23.66
Kidney
8.43
19.94
27.93
27.89
22.26 33.96
77.61
36.28
Liver
2.66
31.72
41.42
78.18
15.67 23.42 132.73 41.24
Loin
0.71
3.13
4.41
5.13
5.73
14.69
23.51
26.87
a
b
c
d
e
139
SE
0.99bcd
2.69bcde
2.43bcd
5.52ce
6.87bcde
18.17bde
1.05bcd
140
Bioavailability of Vitamin A (Retinol) Sources for Cattle
Carlos Alosilla, Jr.1
Lee McDowell
Nancy Wilkinson
Charles Staples
William Thatcher
Michael Blair
Vitamin A destruction occurs in the rumen with retinol losses up to 80%. For the sources of vitamin A
studied Microvit A and Rovamix A appear to be more available to cattle.
Summary
An experiment was conducted to evaluate
bioavailability of five sources of vitamin A
(retinol). Fifty-three yearling Angus  Brahman
cattle, consisting of 39 steers and 14 heifers,
were stratified by BW and gender and randomly
assigned to six high concentrate diet groups
receiving either no vitamin A supplementation
(control), or vitamin A supplemented from the
following sources:
Microvit A (ADISSEO,
Acworth, GA), Rovamix A (DSM, Parsippany,
NJ), Sunvit A, Lutavit A, and Microvit A DLC
(ADISSEO). Vitamin A treatment groups were
fed daily 80,000 IU retinol/animal in a low
retinol concentrate diet (78.5% oats, 10%
cottonseed hulls, 8% molasses, and 2%
cottonseed meal) for 84 d. Every 28 d body
weight was determined and liver biopsies and
plasma were collected and analyzed for retinol
concentrations. All retinol treatments showed
significant
increases
in
liver
retinol
concentrations compared to control animals (P
< 0.0001), which steadily decreased over time.
At all collection times, Microvit A led to
numerically greater concentrations of retinol in
liver than did all other treatments. However, at
experiment termination, there was no significant
difference in liver retinol concentration among
Microvit A, Rovamix A, Lutavit A, and Microvit
A DLC diets. When liver retinol concentrations
at all collection times were considered, Microvit
A and Rovamix A appeared to provide the most
bioavailable vitamin A.
Introduction
Vitamin A generally is supplemented to
ruminant diets to insure maximum health and
productivity.
Unfortunately, considerable
supplemental retinol is destroyed by ruminal
microbes. The amount of concentrate in a diet is
one factor associated with ruminal destruction.
Rode et al. (1990) reported an 80% loss of
vitamin A when cattle were fed 70% concentrate
diets, but, when fed high-forage diets, losses
were only 20%. There is a need for minimizing
ruminal destruction to increase the amount of
vitamin A that reaches the duodenum. In order
to protect vitamin A from pre-intestinal
destruction, gelatin beadlets have been
developed commercially that contain not only
vitamin A but also carbohydrates and
antioxidants to stabilize the vitamin A. The
objective of this study was to compare the
bioavailability of five different forms of
supplemental vitamin A fed to beef cattle.
Procedure
Fifty-three yearling Angus  Brahman cattle,
consisting of 39 steers and 14 heifers, that
141
weighed 750.2 ± 44 lbs, were stratified by
gender and BW and assigned randomly to one of
seven pens and one of eight Calan gates
(American Calan, Northwood, NH) within pens
at the University of Florida Beef Research Unit
in August of 2002. High concentrate dietary
treatments included 78.5% oats, 10% cottonseed
hulls, 8% molasses, and 2% cottonseed meal.
Experimental treatments were control (no
supplemental vitamin A), Microvit A
(ADISSEO, Acworth, GA), Rovamix A (DSM,
Parsippany, NJ), Sunvit A, Lutavit A, and
Microvit A DLC (ADISSEO) fed daily at 80,000
IU/animal.
Vitamin A pre-mixes were
formulated and mixed every two wk. Feed
intake gradually increased, therefore vitamin A
additions changed so that cattle always received
80,000 IU/d. A total of nine cattle were used per
treatment except for eight in the control group.
In each pen, poor quality Bermuda grass hay
(low vitamin A content, 0.71 µg of β-carotene/g)
and water were supplied for ad libitum
consumption.
overall) compared to control and also compared
to the Sunvit A treatment groups (P < 0.05). On
d 84, both Lutavit A and Microvit A DLC were
intermediate and did not differ from control;
Lutavit A also did not differ from Microvit A or
Rovamix A, and Microvit A DLC did not differ
from Microvit A. Similar trends at d 28 and d
56 were evident.
Retinol concentrations in liver (Table 2) were
affected by treatment (P < 0.01) and a treatment
x time interaction was detected (P < 0.0001);
retinol-supplemented cattle had greater (P <
0.05) and more sustained concentrations of liver
retinol compared to a steady decline for the
control group through d 84 (Table 2). Overall
Microvit A had the numerically highest
concentration of liver retinol, but it did not differ
statistically from Rovamix A and Lutavit A.
However, averaged over all sampling times,
Microvit A led to greater liver retinol (P < 0.05)
than did Sunvit A (P < 0.05) and Microvit A
DLC (P < 0.05). Control animals clearly had
decreased retinol concentrations in liver
compared to all vitamin A dietary supplements.
On d 0, 28, 56, and 84, all animals were
restrained and weighed, and liver biopsy and
blood samples were collected. Vitamin A was
analyzed by a standardized HPLC system. The
experiment was a completely random design. All
data were analyzed using the Mixed Procedure
of SAS (SAS for Windows 8e; SAS Institute,
Inc., Cary, NC) for repeated measures. The
model included terms for a covariate (value from
d 0), treatment, time, and treatment  time.
According to previous studies (Hammell et al.,
2000; McDowell, 2000), plasma retinol
concentration is a less reliable indicator of
vitamin A status than is liver retinol
concentration.
Unless there is a severe
deficiency, the liver maintains relatively normal
plasma retinol concentrations.
Our study
demonstrated large differences due to vitamin A
supplementation between treatments and control
in liver retinol concentrations, but only subtle
differences in plasma retinol. The liver is the
site for greatest storage of retinol and is the best
indicator of vitamin A status (McDowell, 2000).
Results
Body weights increased with time (P < 0.0001),
but there were no effects of treatment (P = 0.86)
or of treatment x time (P = 0.31) detected. As
there were no differences among treatments,
control cattle with minimal dietary vitamin A
were able to rely on storage reserves of retinol
for body growth.
Increasing the amount of vitamin A reaching the
duodenum increases the availability for
absorption and storage as is illustrated by
elevated liver retinol concentrations (Table 2).
Vitamin A availability is limited in ruminants
due to losses by ruminal destruction. Ruminal
destruction is especially high when ruminants
are fed high concentrate diets. Rode et al.
(1990) reported that in vitro ruminal microbial
degradation of vitamin A was 80% when the diet
Retinol concentrations in plasma (Table 1) were
affected by treatment (P = 0.01) and time (P =
0.04). There were no interactions between
treatment and time (P = 0.96). Using d 0 values
as the covariate, both Microvit A and Rovamix
A increased (P < 0.05) plasma retinol (d 84 and
142
contained 70% concentrate, whereas diets high
in forage only resulted in a 20% destruction of
vitamin A in vitro.
It was hypothesized that some vitamin A
supplements with protective coatings are more
resistant to rumen destruction or have improved
duodenal availability and that these would result
in greater liver concentrations of retinol. If these
coatings were resistant to intestinal digestion,
then supplemented vitamin A could pass the
duodenum, the site of vitamin A absorption, and
therefore be excreted. Certain products, like
Microvit A and Rovamix A, appear to have
better resistance to ruminal destruction or
improved duodenal availability than other
products tested in this experiment.
Literature Cited
Hammell et al. 2002. J. Dairy Sci. 22:1256.
McDowell. 2002. Vitamins in Animal and Human Nutrition. 2nd ed. Iowa State Press, Ames, IA.
Rode et al., 1990. Can. J. Anim. Sci. 70:227.
1
Carlos Alosilla, Jr., Former Graduate Student; Lee McDowell, Professor; Nancy Wilkinson, Chemist;
Charles Staples, Professor; William Thatcher, Professor; UF/IFAS, Department of Animal Sciences,
Gainesville, FL; Mike Blair, ADISSEO, Acworth, GA.
143
Table 1. Effect of vitamin A sources on plasma retinol concentrations of cattle
Item
n
Day 0
Control
Microvit A
8
9
0.329
0.365
Rovamix A
Sunvit A
SEM1
9
Microvit A
DLC
9
0.297
0.329
0.0212
Lutavit A
9
9
Pretrial plasma retinol, µg/mL
0.333
0.310
Covariate adjusted plasma retinol, µg/mL
ab
0.389
a
0.381ab
0.321b
0.350ab
0.335ab
Day 28
0.331
Day 56
0.312ab
0.350a
0.365a
0.281b
0.339ab
0.345a
Day 84
0.284c
0.357ab
0.369 a
0.286 c
0.324abc
0.305bc
Overall mean
0.308b
0.366a
0.372a
0.296b
0.337ab
a-c
Treatments within the same row not bearing a common superscript differ (P ≤ 0.05)
1
Standard errors of the means (SEM) were the largest among treatments (i.e., for control).
2
SEM for d 0.
3
SEM for covariate adjusted day means.
4
SEM for covariate adjusted overall means.
0.328ab
Table 2. Effect of vitamin A sources on liver retinol concentrations of cattle
Item
n
Control
Microvit A
Rovamix A
Sunvit A
Lutavit A
Microvit A
DLC
8
9
9
9
9
9
158
151
0.0103
0.0174
SEM1
Pretrial liver retinol, µg/g of wet liver
Day 0
158
160
146
131
272
Covariate adjusted liver retinol, µg/g of wet liver
Day 28
121c
183a
153ab
141bc
161ab
158ab
Day 56
90c
178a
163ab
153ab
151ab
135b
Day 84
70 c
187a
183a
143b
168ab
156ab
Overall mean
94c
183a
166ab
145b
160ab
150b
a-c
Treatments within the same row not bearing a common superscript differ (P ≤ 0.05)
SEM were the largest among treatments (i.e., for control).
2
SEM for d 0.
3
SEM for covariate adjusted day means.
4
SEM for covariate adjusted overall means.
1
144
53
104
Forage Nutritional Quality Evaluation of Bahiagrass Selections
Bob Myer1
Ann Blount
Sam Coleman
Jeff Carter
Bahiagrass plant breeding efforts in the past have been based on increasing forage yield. Selection for
increased yield also resulted in a concurrent increase in bahiagrass forage quality.
Summary
Bahiagrass (Paspalum notatum Flugge) is the
major pasture forage in Florida. A bahiagrass
selection breeding program has been ongoing
since 1960 at the Coastal Plain Experiment
Station at Tifton, Georgia to increase forage
yield in ‘Pensacola’ (P. notatum var. sanese
Flugge) bahiagrass. However, the impact of
selection for forage yield on forage nutritional
quality is unknown.
Forage quality was
evaluated from four ‘Pensacola’ derived
selection cycles (C) of bahiagrass (C0 ‘Pensacola’, C4, C9 - ‘Tifton 9’, and C23). A
total of 175 plants per cycle were grown
together in a field at NFREC, Quincy. Forage
from individual one-yr old plants was harvested
by hand on October 3, 2000 and again on
November 15, 2000. The samples were dried,
ground, and analyzed using near-infrared
reflectance spectroscopy (NIRS) for dry matter
(DM), in vitro dry matter digestibility (IVOMD),
neutral detergent fiber (NDF), and crude protein
(CP). Cycle means (% DM basis combined over
both harvest dates) for IVOMD, NDF and CP
were 49.7, 81.0 and 14.2; 50.3, 79.7 and 13.7;
52.8, 78.7 and 13.2; and 52.0, 78.5 and 12 .9 for
C0, C4, C9 and C23, respectively. The greater
average IVOMD of C4 vs. C0 was different (P =
0.03) as well as C9 vs. C4 (P < 0.001).
Therefore, in addition to increased forage yield,
there was evidence that forage quality (IVOMD)
also increased with advancing selection cycle.
Selection for improved nutritional quality
through plant breeding may be possible.
Introduction
Bahiagrass is the major pasture forage crop in
Florida and throughout the southern Gulf Coast.
As a C4 tropical grass, its forage nutritional
quality is low, lower than typically noted for C3
temperate grasses, such as ryegrass, at
comparable stages of growth and development.
Dr. G. W. Burton, a plant breeder with USDA
ARS, Tifton, GA, developed and used restricted
recurrent phenotypic selection (RRPS) breeding
procedure to improve bahiagrass forage yield.
Starting in 1960, Burton selected plants annually
for 24 yr using this procedure, which resulted in
morphology of the plants towards a more upright
growth habit as well as greater forage mass.
Whether or not forage nutritional quality was
improved is not known. Thus, the objective of
this research was to evaluate nutritional quality
of bahiagrass selections from four ‘Pensacola’
derived RRPS selection cycles.
Material and Methods
Bahiagrass seed from four RRPS selec-
145
tion cycles [C0 (Pensacola), C4, C9 (Tifton 9)
and C23] were obtained from G. W. Burton,
USDA-ARS, Coastal Plain Experiment Station,
Tifton, GA, and used in this study. From this
seed supply, a total of 175 plants of each cycle
were grown in a greenhouse and then
transplanted during July 1999 to a field at
NFREC Quincy, FL (30.3° N Lat.). Beginning
September 1999, foliage was harvested every 6
to 8 wk. Harvest consisted of the total top
growth that occurred at 4 in above the crown of
the individual plants. On August 15, 2000, all
plant crowns were hand clipped to 4 in diameter
and the foliage clipped to 4 in height. On
October 2, 2000 and again on November 15,
2000, foliage growth of individual plants was
cut by hand to a common height of 4 in. Foliage
was dried, weighed and recorded. In all, an
average of 164 forage samples per cycle per
harvest was obtained. Forage was not obtained
from all 175 plants per cycle per harvest due to
some plant attrition or plants not having
sufficient forage.
When combined over both harvests, an increase
in IVOMD and decreases in NDF and CP
concentrations were noted when going from C0
to C4 (P=0.03; P<0.001; P<0.001, respectively),
and again from C4 to C9 (P<0.001 for all; Table
1). A small decrease (P<0.01) in IVOMD was
noted from C9 to C23. While IVOMD was
lower for C23 compared with C9, the value was
still greater when compared with C4 or CO
(P<0.01). The further decrease noted with NDF
of C23 vs. C9, however, was not significant
(P>0.10). The trend for a decrease in CP was
continued as the decrease between C9 and C23
was significant (P<0.01). The peak at C9 for
IVOMD was mostly the result of the drop in
IVOMD for C23 compared with C9 (P<0.01)
noted for the November harvest; values were
similar (P>0.10) for the October harvest (Figure
1).
The November harvest samples were greater
(P<0.01) in IVOMD (52.4 vs. 50.1%) and CP
(14.6 vs. 12.5%) than the October harvest
samples; NDF was similar (P>0.10; 80 vs. 79%;
Figure 1). The increases noted were probably a
reflection of the cooler weather during the 6 wk
prior to the November harvest than prior to the
October harvest.
The dried forage samples were ground and
analyzed for DM, IVOMD, NDF and CP using
NIRS.
The NIRS was calibrated from a
subsample of 275 samples which were analyzed
using wet chemistry procedures.
Forage yield has been reported previously. As
expected, an increase with increasing selection
cycle was noted, peaking at C9 (60% increase
vs. C0) with no further increase with C23.
Data were analyzed using GLM of SAS. The
model included harvest date and cycle. The
individual plant was the experimental unit.
Significant effects were separated using
LSMEANS comparison with the PDIFF option
of SAS.
From these results, there was evidence that
forage nutritional quality did increase with
advancing selection cycle. This finding is based
on the increase in IVOMD and the decrease in
NDF as selection cycle increased from 0 to 23,
in particular from C0 to C9. Crude protein
concentration actually decreased with increasing
selection cycle; however, animal nutritionists
often place more emphasis on IVOMD and NDF
as determinants of forage nutritional quality than
CP. While the bahiagrass RRPS selection goal
was to increase forage yield, results of our study
indicated evidence of a concurrent improvement
in forage nutritional quality.
Results
The values obtained for IVOMD and NDF in
this study were typical of late grazing season
bahiagrass; however, the CP values were
greater. The bahiagrass plants were well
fertilized during the study which could explain
the greater CP concentrations. October and
November samplings were done rather than
during the late spring and summer mo as forage
quality is typically lowest for bahiagrass during
autumn. Differences noted would be more
meaningful than earlier sampling when quality
values would overall be higher.
In addition, variation for each parameter
146
measured within each cycle was noted, and this
variation was consistent across the cycles. For
example, the variation (one standard deviation)
for IVOMD averaged 2.8 (range of 2.7 to 2.9).
This variation is desirable for plant breeding
improvement. Therefore, breeding for improved
forage quality within a cycle, as well as across
cycles, may be possible.
Table 1. Composition of bahiagrass cycles (% dry matter basis; combined over both harvests).
Selection cycle
Item
C0
C4
C9
C23
SEa
b
IVOMD
49.7
50.3
52.8
52.0
0.10
NDFc
81.0
79.7
78.7
78.5
0.10
Crude proteind
14.2
13.7
13.2
12.9
0.09
a
Standard error of the mean, n = average of 164/cycle/harvest.
b
In vitro organic matter digestibility. C0 vs. C4, P < 0.03; C4 vs. C9, P < 0.001; C9 vs. C23, P < 0.01.
c
Neutral detergent fiber. C0 vs. C4, P < 0.001; C4 vs C9, P < 0.001; C9 vs. C23, P > 0.10.
d
C0 vs. C4, P < 0.001; C4 vs. C9, P < 0.001; C9 vs. C23, P < 0.01.
1
Bob Myer, Professor, Ann Blount, Associate Professor, and Jeff Carter, Former Assistant Professor,
UF-IFAS, North Florida Research and Education Center, Marianna, FL; and Sam Coleman, Research
Animal Scientist, USDA ARS, Sub-tropical Agriculture Research Station, Brookville, FL.
147
IVOMD
70
60
50
40
SE = 0.13
30
0
4
9
23
9
23
NDF
100
90
80
70
SE = 0.13
60
0
4
CP
20
15
10
5
SE = 0.12
0
0
4
9
23
Selection cycle
Figure 1. Mean values for each harvest of bahiagrass selection cycles (%, DM basis; ▲
▲=
Oct. harvest and ■ = Nov. harvest). IVOMD = in vitro organic matter digestibility; NDF =
neutral detergent fiber; CP = crude protein.
148
Warm-Season Legume Hay Or Soybean Meal Supplementation Effects On
The Performance Of Lambs
Jamie Foster1
Adegbola Adesogan
Jeffery Carter
Bob Myer
Ann Blount
This study showed that perennial and annual peanut hays are quality forages that improve intake,
digestibility, and nitrogen retention when supplemented to bahiagrass hay. Cowpea and soybean hay
have lower quality, but they are also promising legume supplements.
Perennial and annual peanut hays were the best
supplements for the lambs.
Summary
This study determined how supplementing
bahiagrass hay (Paspalum notatum Flügge cv.
‘Pensacola’) with soybean (Glycine max (L.)
Merr.) meal or warm-season legumes affects
intake, digestibility, and nitrogen (N) utilization
by lambs. Forty-two Dorper x Katadhin
crossbred lambs (67 ± 12 lb) were fed ad libitum
amounts of bahiagrass hay alone (six-wk
regrowth), or bahiagrass hay supplemented
(50% dietary dry matter, DM) with hays of
annual peanut (Arachis hypogaea (L.) cv.
‘Florida MDR98’), cowpea (Vigna unguiculata
(L.) Walp. cv. ‘Iron clay’), perennial peanut
(Arachis glabrata Benth. cv. ‘Florigraze’),
pigeonpea (Cajanus cajan (L.) Millsp. cv. ‘GA2’), or soybean (cv. ‘Pioneer 97B52’), or with
enough soybean meal (4.25% of dietary DM) to
match the average dietary crude protein (CP;
10.8%)
concentration
of
the
legume
supplemented diets. Diets were fed to six lambs
per treatment for two, consecutive 21-d periods.
Annual and perennial peanut, cowpea, and
soybean hays increased DM intake, but DM
digestibility
was
only
increased
by
supplementation with annual or perennial
peanut hays. Nitrogen intake, digestibility, and
retention were increased by all supplements and
these responses were greatest when perennial
peanut hay was supplemented followed by
annual peanut hay. Warm-season legumes are
promising supplements for growing ruminants.
Introduction
The quantity of bahiagrass and bermudagrass
[Cynodon dactylon (L.) Pers.] that is available
for winter grazing is limited because these
grasses become dormant in the winter and do not
provide sufficient nutrients to optimize the
growth of beef cattle through the grazing season.
Supplementing poor quality basal grass diets
with legumes increases total feed intake and
sometimes improves digestibility. In the United
States, alfalfa (Medicago sativa L.) is the
legume most commonly fed to livestock, but it
does not persist in the Gulf Coast region.
Perennial peanut is a warm-season legume
adapted to this region and it is the main forage
legume in Florida. However, because it is sprigplanted, it is more difficult and expensive to
establish than tropically adapted, seeded warmseason legumes such as cowpea, soybean,
pigeonpea, or annual peanut. Little is known
about how performance of ruminant livestock is
affected by supplementing bahiagrass hay with
seeded warm-season legume hays. This study
aimed to determine feed intake, digestibility, and
nitrogen (N) balance of lambs fed bahiagrass
hay supplemented with soybean meal, or hays of
perennial peanut, annual peanut, soybean,
cowpea, or pigeonpea. Lambs are excellent
models for examining supplementation effects
149
on nutrient utilization in growing cattle.
average CP concentration (10.8% DM basis) of
the legume diets.
Forage Production
Legume hays were produced at the North
Florida Research and Education Center in
Marianna, FL, (31° N) and fed at the
Department of Animal Sciences, University of
Florida, Gainesville, Florida. To prepare the
field for planting seeded legumes, it was limed,
fertilized, and plowed. In May of 2005, seeds
were inoculated with the appropriate rhizobia
drilled at 50 lb/ac and 6-in row spacings.
Legumes were harvested at the following
maturity stages: pod yellowing for cowpea
(Twidwell et al., 2002), pod setting for
pigeonpea (Le Houérou, 2006), and stage R6
(pod with full size seed at one of the four
uppermost nodes and completely unrolled
leaves) for soybean (Sheaffer et al., 2001).
Established stands of perennial and annual
peanut (self reseeding) were harvested as first
cuttings in June and September of 2005,
respectively. A mower-conditioner was used to
harvest the legumes; windrows were turned with
an inverter after 24 h, and then rolled into round
bales. An established stand of bahiagrass was
harvested as a six-wk regrowth and rolled into
round bales.
Sample Collection and Analyses
Samples of each feed were taken daily during
the 7-d collection period and daily refusals were
weighed and stored. Total fecal and urine output
were collected daily from each lamb, weighed,
and a subsample used for analysis. Samples of
feed were dried, ground, and analyzed for DM,
organic matter (OM), CP, neutral detergent fiber
(NDF), acid detergent fiber (ADF), lignin, and
in vitro true digestibility (IVTD). Feces was
analyzed for DM after drying and grinding, and
urine was analyzed for N.
Statistical Analyses
The experimental design was completely
randomized. Data were analyzed with PROC
MIXED (SAS Inst. Inc., Cary, NC). The model
for analyzing chemical composition of forage
included forage species and period (random
variable). The model for analyzing intake,
digestibility, and N retention included dietary
treatment, period, dietary treatment × period,
and lamb (random variable). Significance was
declared at P<0.05.
Forage Chemical Composition
Dry matter concentrations were not different
among forages, but OM concentration was
greater in all other hays than in perennial peanut
hay (Table 1). As expected, CP concentration
was least (P<0.01) in bahiagrass hay. Among
legumes, CP concentrations were greater in
annual and perennial peanut hays than in cowpea
and pigeonpea hays. Neutral detergent fiber
concentration was greatest (P<0.01) in
pigeonpea hay followed by bahiagrass hay, and
least in annual and perennial peanut hays. The
greatest (P < 0.01) ADF concentration was in
pigeonpea hay and the least (P<0.01)
concentration was in perennial peanut hay.
Lignin (P<0.10) concentration was greater in
pigeonpea hay than the other hays. In vitro true
DM digestibility was greatest (P<0.01) in
perennial peanut hay followed by annual peanut
hay. Bahiagrass hay contained lower (P<0.01)
IVTD than all legumes except pigeonpea hay
Animals, Feeding, and Housing
Forty-two Dorper × Katadhin cross ram lambs
weighing 67 ± 12 lb were used for the
experiment. Lambs were stratified by weight
and randomly assigned to seven treatments (six
lambs per treatment per period).
The
experiment had 2 periods each containing 14 d
of adaptation to diets and 7 d of measurement,
and each lamb received a different diet in each
period. Lambs were fitted with canvas feces
collection bags and housed in individual
metabolism crates adapted for collection of
urine. Lambs were fed ad libitum (110% of
previous days’ intake) diets consisting of
bahiagrass hay alone or bahiagrass hay
supplemented (50% of diet DM) with perennial
peanut hay, annual peanut hay, cowpea hay,
pigeonpea hay, soybean hay, or soybean meal
(4.25% of diet DM). The soybean meal
inclusion level was aimed at matching the
150
which contained the least (P<0.01) IVTD.
Perennial and annual peanuts had greater IVTD
than other legumes due to their lower NDF and
ADF concentrations.
and the greatest (P<0.01) values occurred in
lambs fed perennial peanut, followed by annual
peanut. Legume hay supplementation increased
N intake because of the greater CP
concentrations of the legumes versus bahiagrass,
as well as the greater DM intake of most of the
legume-supplemented diets. Nitrogen retention
increased accordingly because all supplements
increased N digestibility and most supplements
decreased the proportion of intake N lost as
urine (data not shown).
Intake, Digestibility, and Nitrogen Retention
With the exception of pigeonpea hay, legume
hay supplementation increased intake of DM
(Table 2). Intake of DM was greatest (P<0.01)
in lambs supplemented with perennial peanut
hay, followed by annual peanut hay, and they
were lower in lambs consuming bahiagrass hay
alone or pigeonpea hay than those consuming
other legume hays. Intake of DM was not
improved by addition of soybean meal.
Digestibility of DM was only increased by
perennial or annual peanut hay supplementation,
and the values were greater when perennial
peanut was supplemented. Unlike the other
legumes, annual and perennial peanut are
prostrate, spreading plants with relatively high
leaf-to-stem ratios, therefore they have low
concentrations of NDF and ADF, and
consequently, they are more digestible than the
other legumes. Pigeonpea had higher NDF and
ADF concentrations because of its thick, woody
stems, which probably increased gut fill, thereby
decreasing intake.
The fact that supplementation with N from
legume hays or soybean meal increased N
intake, digestion, and retention indicates that
supplementation is necessary for optimizing the
utilization of bahiagrass in lambs. At the
moderate dietary CP concentration evaluated,
supplementation with annual and perennial
peanut hays was more effective than soybean
meal supplementation at improving N intake,
digestion, and retention. Perennial peanut and
annual peanut were the most promising legume
supplements because they resulted in the
greatest DM intakes and digestibility and the
greatest N retention.
Pigeonpea hay
supplementation increased N retention, but did
not improve DM intake and it reduced DM
digestibility; therefore, it was the least desirable
supplement.
This study suggests that
supplementing bahiagrass with warm-season
legumes can improve the performance of
growing sheep and cattle.
Nitrogen intake was increased (P<0.01) by
supplementation regardless of supplement type
and it was greatest (P<0.01) in lambs fed
perennial peanut hay, followed by (P<0.01)
annual peanut hay. Nitrogen retention and
digestibility were increased by all supplements
Literature Cited
Le Houérou, 2006. http://www.fao.org/ag/agP/AGPC/doc/gbase/data/Pf000150.HTM
Sheaffer et al. 2001. Agron. J. 93:99.
Twidwell et al. 2002. S. Dakota State Univ. Circular 8070.
1
Jamie Foster, Former Graduate Student; Adegbola Adesogan, Associate Professor, UF/IFAS,
Department of Animal Sciences, Gainesville, Florida; and Jeffery Carter, Former Assistant
Professor; Bob Myer, Professor; Ann Blount, Professor, North Florida Research and Education
Center, Marianna, Florida.
151
Table 1. Chemical composition and in vitro true DM digestibility (IVTD) of hays.
Item2
Annual Perennial
peanut
peanut
Cowpea Pigeonpea Soybean SEM1
1.8
91.0
90.8
91.5
91.8
91.6
b
c
b
a
ab
0.5
92.4
90.8
92.6
94.7
93.8
ab
a
c
c
b
0.4
14.7
15.2
11.7
12.2
13.5
DM, %
OM, % DM
Bahiagrass
91.1
94.5a
CP, % DM
8.1d
NDF, % DM
73.8b
46.2e
43.3f
62.2c
78.6a
59.0d
1.0
ADF, % DM
39.8cd
37.8d
32.1e
48.7b
60.2a
42.8c
1.3
6.2b
7.9b
6.7b
9.5b
17.1a
9.6b
1.1
Lignin, % DM
1.1
50.7d
71.4b
77.2a
57.9c
35.1e
57.4c
IVTD, %
1
Standard error of the mean values reflect the variation of samples collected daily and composited within
each of 2 Periods (n=2).
Abbreviations: Dry matter (DM); organic matter (OM); crude protein (CP); neutral detergent fiber
(NDF);
acid detergent fiber (ADF).
Within a row means without a common superscript letter differ (P < 0.05).
Table 2. Intake and apparent digestibility of dry matter (DM), nitrogen (N), and N retention of lambs fed bahiagrass
hay supplemented with warm-season legume hays or soybean meal (SBM)
Bahiagrass
SBM
Annual
peanut
Perennial
peanut
Cowpea
Pigeonpea
Soybean
SEM1
1.5ef
1.6de
2.1b
2.4a
1.8cd
1.3f
1.9c
0.06
DM Digestibility, %
58.5cd
60.3c
64.3b
67.8a
58.8cd
56.3d
60.7c
0.9
N intake, lb/d
0.019e
0.034c
0.039b
0.047a
0.028d
0.026d
0.034c
0.0011
Item
DM Intake, lb/d
e
N digestibility, %
46.5
Retained N, lb/d
0.0044d
56.8
cd
0.0092c
62.4
b
0.015b
66.8
a
0.023a
54.0
d
0.010c
55.6
cd
0.0090c
58.1
c
0.011c
1
1.1
0.0012
Standard error of the mean values reflect the variation of measurements taken from each of the lambs on a treatment in
each of 2 periods (n = 12 for intake and digestibility; n = 10 for retained N).
Within a row means without a common
superscript letter differ (P < 0.05).
152
Warm-Season Legume Haylage or Soybean Meal Supplementation Effects on
the Performance of Lambs
Jamie Foster1
Adegbola Adesogan
Jeffery Carter
Bob Myer
Ann Blount
This study showed that perennial and annual peanut and cowpea haylages are quality forages that
improve intake, digestibility and nitrogen retention when supplemented to bahiagrass hay basal diets.
Summary
This study determined how supplementing
bahiagrass haylage (Paspalum notatum Flügge
cv. ‘Tifton 9’) with soybean (Glycine max (L.)
Merr.) meal or warm-season legume haylages
affected the performance of lambs. Forty-two
Dorper x Katadhin lambs (60 ± 11 lb) were fed
ad libitum bahiagrass haylage alone, or
supplemented with soybean meal or haylages of
annual peanut (Arachis hypogea (L.) cv.
‘Florida MDR98’), cowpea (Vigna unguiculata
(L.) Walp. cv. ‘Iron clay’), perennial peanut
(Arachis glabrata Benth. cv. ‘Florigraze’), or
pigeonpea (Cajanus cajan (L.) Millsp. cv. ‘GA2’). Legumes were supplemented at 50% of the
diet and soybean meal fed to match the average
crude protein (CP) concentration (12.8%) of
legume diets. Haylages were harvested, wilted
to 45% dry matter (DM), baled, wrapped in
polyethylene, and ensiled for 180 d. Each diet
was fed to seven lambs for 21 d, and then to four
lambs for 21 d.
Supplementation with
pigeonpea decreased DM intake but other
supplements increased DM intake by
approximately the same amount. Soybean meal
supplementation increased DM digestibility but
pigeonpea supplementation decreased DM
digestibility. Nitrogen (N) intake, digestibility,
and retention were increased by all supplements
except pigeonpea haylage and these responses
were greatest when soybean meal was
supplemented. In conclusion, perennial peanut,
annual peanut, and cowpea haylages are
promising protein supplements for growing
lambs.
Introduction
Protein supplementation is often necessary to
meet nutrient requirements of ruminant
livestock. Legumes are commonly utilized as
protein supplements because their symbiotic
relationship with microbes that fix atmospheric
N increases their CP concentrations. Legumes
also increase soil N status, and this may be a
more economical method of improving N in
soils than inorganic fertilizer application,
especially with increasing fuel, and thus
fertilizer costs. Alfalfa (Medicago sativa L.) is
the most commonly used legume supplement in
ruminant rations in the United States. However,
alfalfa does not persist in southern states due to
diseases, insects, and nematodes; therefore,
research on tropically-adapted warm-season
seeded legumes that can be used as protein
supplements in the Southeast is needed. Due to
inclement weather during harvest in some
subtropical and tropical locations there is
considerable interest in conserving such legumes
as haylage rather than hay, but only a few
studies on the feeding value of ensiled warmseason legumes exist. This study aimed to
determine the feed intake, digestibility, and N
balance of lambs fed bahiagrass haylage
supplemented with soybean meal or haylages
made from either perennial peanut, annual
peanut, cowpea, or pigeonpea.
153
were dried, ground, and analyzed for DM,
organic matter (OM), CP, neutral detergent fiber
(NDF), acid detergent fiber (ADF), lignin,
water-soluble carbohydrates (WSC), and in vitro
true digestibility (IVTD). Feces was analyzed
for DM after drying and grinding, and urine was
analyzed for N.
Forage Production and Ensiling
Legume haylages were produced at the North
Florida Research and Education Center in
Marianna, FL (31° N). To prepare the field for
planting annual legumes the field was limed,
fertilized, and plowed. Cowpea and pigeonpea
seeds were inoculated with the appropriate
rhizobia, drilled at 50 lb/ac in May of 2006, and
harvested at the recommended maturity stages
which are pod yellowing for cowpea (Twidwell
et al., 2002) and pod setting for pigeonpea (Le
Houérou, 2006). Established stands of perennial
and annual peanut (self reseeding) were
harvested as first cuttings in August 2006. An
established bahiagrass stand was fertilized and
harvested as the third cutting after five-wk of
regrowth. Forages were cut with a mower
conditioner, windrows were wilted to 45% DM,
rolled into small round bales, and wrapped with
a single roll wrapper.
The experimental design was completely
randomized. Data were analyzed with PROC
MIXED (SAS Inst. Inc., Cary, NC). The model
for analyzing chemical composition of forage
included forage species and period (random
variable). The model for analyzing intake,
digestibility, and N retention included dietary
treatment, period, dietary treatment × period,
and lamb (random variable). Significance was
declared at P<0.05.
Forage Chemical Composition
The DM and OM concentrations of all haylages
were similar (P>0.10) (Table 1). Among the
legumes, the CP concentration of annual peanut
haylage was greater than that of pigeonpea
haylage. Concentration of NDF was greatest
(P<0.10) in pigeonpea and bahiagrass haylages,
but pigeonpea had greater (P<0.10) ADF
concentration than the other haylages. The
lignin concentrations of cowpea and pigeonpea
haylages tended (P≤0.08) to be greater than that
of bahiagrass, but WSC concentration was not
different (P>0.10) among haylages. The IVTD
was greater in annual and perennial peanut
haylages than bahiagrass and pigeonpea
haylages, and pigeonpea had the least (P<0.01)
IVTD. Differences in IVTD for these haylages
can be partly explained by differences in their
NDF, ADF, and lignin concentrations. Apart
from pigeonpea, legume haylages had greater
IVTD than bahiagrass haylage because they
contained less NDF.
Although the NDF
concentration of pigeonpea was similar to that of
bahiagrass, pigeonpea had a lower IVTD
because it contained more ADF.
Animals, Feeding, and Housing
Forty-two Dorper × Katadhin cross ram lambs
weighing 60 ± 11 lb were used for the
experiment. Lambs were stratified by weight
and randomly assigned to six treatments (seven
lambs per treatment during Period 1, and four
lambs per treatment during Period 2) in a
completely randomized design with two periods.
Each period consisted of 14 d of adaptation to
diets and 7 d of measurement and each lamb
received a different diet in each period. Lambs
were fitted with canvas feces collection bags and
housed in individual metabolism crates adapted
for collection of urine. Lambs were fed ad
libitum (110% of previous days’ intake) diets
consisting of bahiagrass haylage alone or
bahiagrass haylage supplemented (50% of diet
DM) with one of the legume haylages or with
soybean meal at 8% of diet DM. The soybean
meal inclusion level was aimed at matching the
average CP concentration (12.8% DM basis) of
the legume diets.
Sample Collection and Analyses
Samples of each feed were taken daily during
the 7 d collection period and daily refusals were
weighed and stored. Total fecal and urine output
was collected daily from each lamb, weighed,
and a subsample analyzed. Samples of feed
Intake, Digestibility, and Nitrogen Retention
All supplements except pigeonpea, increased
DM intake (Table 2) and perennial peanut
supplementation gave greater values than
154
cowpea supplementation. Apparent digestibility
of DM was greater (P<0.01) in sheep fed
soybean meal than in sheep fed bahiagrass
haylage
alone
or
pigeonpea
haylage.
Digestibility of DM was similar in lambs fed
bahiagrass haylage alone and those fed legume
supplements, except pigeonpea which had lower
values. Nitrogen intake was greatest (P<0.01) in
lambs fed soybean meal, followed by annual
peanut haylage, and least (P>0.10) in lambs fed
bahiagrass haylage alone or pigeonpea haylage.
Digestibility of N was greatest (P<0.01) in
lambs supplemented with soybean meal,
followed by annual and perennial peanut and
cowpea haylages, and least (P<0.01) in lambs
fed bahiagrass haylage alone or pigeonpea
haylage. Retained N was greatest in lambs fed
soybean meal, followed by annual or perennial
peanut and cowpea haylages, and least (P<0.01)
in lambs fed bahiagrass haylage alone or
pigeonpea haylage.
The N status of supplemented lambs was better
than that of lambs fed only bahiagrass haylage.
Perennial peanut and annual peanut haylage
were the best legume supplements because they
increased DM intake, N digestibility, and N
retention relative to feeding bahiagrass haylage
alone. Soybean meal supplementation resulted
in the greatest N intake, digestibility, and
retention and the greatest DM digestibility,
indicating that it was the best supplement.
Nevertheless, perennial peanut and annual
peanut and cowpea haylages are promising
supplements for sheep and cattle fed bahiagrass
diets.
When basal grass diets of sheep are
supplemented with legumes, DM intake
increases because legumes have a faster rate of
passage through the rumen. Supplementation
with pigeonpea haylage decreased DM intake
because its thick, woody stems would have
caused greater gut fill than stems of bahiagrass.
In contrast, addition of soybean meal increased
DM intakes because the increased protein supply
to ruminal microbes increased DM digestibility.
Literature Cited
1
Jamie Foster, Former Graduate Student; Adegbola Adesogan, Associate Professor, UF/IFAS,
Department of Animal Sciences, Gainesville, Florida; and Jeffery Carter, Former Assistant Professor;
Bob Myer, Professor; Ann Blount, Professor, UF/IFAS, North Florida Research and Education
Center, Marianna, Florida.
155
Table 1. Chemical composition and in vitro true DM digestibility (IVTD) of haylages ensiled for at
least 180 d
Item2
Annual
peanut
54.3
Perennial
peanut
49.2
SEM1
1.32
DM, %
0.79
OM, % DM
96.9
95.7
95.9
93.9
95.8
c
a
ab
ab
bc
1.23
CP, % DM
9.6
18.7
15.8
16.0
13.7
a
b
b
b
a
2.40
NDF, % DM
67.8
39.6
40.0
44.1
65.0
b
bc
c
bc
a
1.99
ADF, % DM
32.2
25.3
24.1
29.8
48.6
2.54
Lignin, % DM
6.2
11.7
7.1
14.4
14.0
1.32
WSC, % DM
5.1
7.2
4.4
4.4
2.6
b
a
a
ab
c
3.11
IVTD, %
60.4
73.8
76.9
68.6
38.3
1
Standard error of the mean values reflect the variation of samples collected daily and composited
within period (n=2).
Bahiagrass
52.1
Cowpea
53.0
Pigeonpea
47.6
2
Abbreviations: Dry matter (DM); organic matter (OM); crude protein (CP); neutral detergent fiber
(NDF); acid detergent fiber (ADF); water soluble carbohydrates (WSC).
abc
Table 2. Intake and apparent digestibility of dry matter (DM), nitrogen (N), and N retention in lambs fed
bahiagrass hay supplemented with warm-season legume haylages or soybean meal (SBM).
Item
DM intake, lb/d
DM digestibility, %
N intake, lb/d
Bahiagrass
SBM
Annual
peanut
Perennial
peanut
Cowpea
Pigeonpea
SEM1
1.4c
65.2b
0.02d
1.7ab
68.0a
0.05a
1.7ab
65.5ab
0.04b
1.8a
66.7ab
0.048c
1.6b
67.0ab
0.04c
1.1d
58.7c
0.02d
0.05
0.9
0.001
N digestibility, %
58.5c
73.9a
68.0b
67.6b
67.6b
61.1c
1.24
c
a
b
b
b
c
Retained N, lb/d
0.005
0.020
0.015
0.013
0.013
0.006
0.002
1
Standard error of the mean values reflect the variation of measurements taken on each lamb in each of 2
periods (n = 11 for intake and digestibility; n = 10 for retained N).
abc
156
Annual Legumes to Complement Warm-Season Perennial Grass Forage
Systems in North Florida
Jamie Foster1
Adegbola Adesogan
Jeffrey Carter
Lynn Sollenberger
Robert Myer
Ann Blount
This study indicated that cowpea and soybean are promising quality forages for hay and haylage
production in North Florida
Summary
This study determined the herbage mass, leaf-tostem ratio, and nutritive value of soybean
[Glycine max (L.) Merr.], cowpea [Vigna
unguiculata (L.) Walp.], and pigeonpea
[Cajanus cajan (L.) Millsp.] grown in North
Florida. Forages were grown in each of four
blocks in three yr and harvested biweekly until
the recommended maturity stage. Herbage mass
of the forages increased through the growing
season, and at the respective maturity stages
soybean (3.8 tons dry matter (DM)/ac) and
pigeonpea (3.9 tons DM/ac) had greater
herbage mass than cowpea (2.3 tons DM/ac).
Leaf-to-stem ratio decreased with maturity after
a slight initial increase in all forages. At
harvest, pigeonpea contained 12% crude protein
(CP; DM basis) and 35% in vitro true DM
digestibility (IVTD), soybean contained 18% CP
and 73% IVTD, and cowpea contained 19% CP
and 69% IVTD. Soybean and cowpea have
potential to provide high quality forage to
livestock in North Florida.
mid-to-late fall. Warm-season legumes can
provide the needed supplementary nutrients, and
when stored as hay or haylage, they can be fed
in the winter to supplement stored and
stockpiled grasses. The increasing costs of fuel
and fertilizer have made such legumes more
attractive to producers and necessitated
evaluation of their yield and nutritive value. The
objective of this study was to compare the
herbage mass, chemical composition, IVTD, and
leaf-to-stem ratio of cowpea (cv. ‘Iron clay’),
soybean (cv. ‘Pioneer 97B52’) and pigeonpea
(cv. ‘GA-2’).
In each of three yr, cowpea, soybean, and
pigeonpea were grown at the North Florida
Research and Education Center in Marianna, FL.
Each legume was grown on a replicated plot
within each of four blocks. The field was
prepared by plowing and fertilizing with P and
K to soil test recommendation. Immediately
prior to planting, seeds were inoculated with the
appropriate rhizobia and drilled at 50 lb/ac and
6-in row spacing. Planting dates for yr one
(2005) and two (2007) were 9 and 10 May,
respectively.
Introduction
In Florida and much of the Southern USA,
bahiagrass [Paspalum notatum Flügge] and
bermudagrass [Cynodon dactylon (L.) Pers.] are
the main pasture forages. However, their
availability for winter grazing is limited and
their digestibility and CP concentration are often
insufficient for growing and lactating cattle in
Duplicate forage samples were taken from each
plot with mechanical clippers from a 0.2-m2 area
and harvested to a 2-in stubble height after
157
plants reached approximately 11 in height.
Sampling continued every 2 weeks until harvest
at the following recommended maturity stages:
pods began to turn yellow for cowpea (Twidwell
et al., 2002), pod setting for pigeonpea (Le
Houérou, 2006), and stage R6 (full size seed in
pods at one of the four uppermost nodes and
completely unrolled leaves) for soybean
(Sheaffer et al., 2001). Leaf-to-stem ratio was
measured on duplicate samples from each plot
after removal of leaves at the node. Samples
were ground and analyzed for CP, neutral
detergent fiber (NDF), and IVTD. Economics of
producing these forages was compared to that
for perennial and annual peanut forage using
models of Hewitt (2006) and Prevatt (2008).
soybean cultivar used in this experiment was late
maturing (VII), with upright, tall (1.5 to 2.0 m)
growth and the proportion of leaf declined
through maturity at R7 stage. Pigeonpea is a
tree-like legume that grows tall and has a woody
main stem, and its small leaves begin to senesce
at 9 WAP. Pigeonpea and soybean had greater
herbage mass than cowpea because of their
upright growth habit and thicker stems which
supported greater herbage mass.
Nutritive Value
The CP concentration of each forage decreased
through the growing season (Figure 3). Between
8 WAP and the respective recommended harvest
stages, cowpea had the greatest CP
concentration, whereas soybean had a greater CP
concentration than pigeonpea from 10 WAP to
the recommended harvest stage for pigeonpea.
Pigeonpea had a greater NDF concentration than
the other legumes between 10 and 14 WAP, and
soybean had a greater NDF concentration than
cowpea between 8 and 14 WAP. The IVTD of
annual legumes decreased with maturity in
pigeonpea and cowpea, but the rate and extent of
the decrease was greater in pigeonpea. From 8
to 14 WAP, cowpea had the greatest IVTD,
followed by soybean. Soybean and cowpea
have more potential as forages for ruminants
than pigeonpea. Cowpea is a promising energy
and protein supplement but the herbage mass is
relatively low. The greater herbage mass and
high energy and protein concentration of
soybean makes it ideal for producing large
quantities of quality hay or haylage. Pigeonpea
is only recommended for grazing cattle or
storage as hay or haylage if it is less than 8
WAP.
Economics
Establishment of perennial peanut is more
expensive than establishment of the other
legumes; however, the annual maintenance cost
of the seeded legumes is greater because they
are planted each yr (Table 1). Cowpea
produced the least herbage mass (Table 1) and
therefore had the least net present value after 20
yr (Table 2). Perennial peanut is the best long
term investment, but the other legumes will
produce earlier returns on the investment.
The experimental design was a randomized
complete block. Data were analyzed as repeated
measures with PROC MIXED (SAS Inst. Inc.,
Cary, NC). The model included yr, forage
species, week after planting (WAP), block and
the interactions. Significance was declared at P
< 0.05.
Herbage Mass and Leaf-to-stem Ratio
There were no yr or yr × forage species
interactions therefore results shown are means
across yr. Figure 1 shows the herbage mass for
each legume through the growing season.
Pigeonpea reached the recommended harvest
stage at 14 WAP, whereas soybean and cowpea
reached their recommended harvest stages at 16
and 20 weeks per planting, respectively. At the
recommended maturity stage, soybean and
pigeonpea had greater herbage mass than
cowpea. Figure 2 shows that leaf-to-stem ratio
decreased with maturity after a slight initial
increase in all forages. From 10 to 14 WAP, the
leaf-to-stem ratio of cowpea was greater than
those of pigeonpea and soybean, which were
similar. Herbage mass and leaf-to-stem ratio
differences among the species are due to
morphological and physiological differences.
‘Iron clay’ cowpea is a viney, low growing plant
with large leaves and an indeterminate growth
habit; therefore, it continued to produce new
foliage after flowering and leaves did not
senesce as soon as the other species. The
158
Literature Cited
Hewitt, 2006. http://nfrec.ifas.ufl.edu/Hewitt/budgets.htm
Prevatt, 2008. http://www.ag.auburn.edu/agec//pubs/budgets/2008/forcrop08.php
Sheaffer et al. 2001. Agron. J. 93:99.
1
Jamie Foster, Former Graduate Student; Adebola Adesogan, Associate Professor, UF/IFAS, Department
of Animal Sciences, Gainesville, Florida; and Jeffery Carter, Former Assistant Professor; Bob Myer,
Professor; Ann Blount, Professor, UF/IFAS, North Florida Research and Education Center, Marianna;
Florida Lynn Sollenberger, Professor, UF/IFAS, Agronomy Department.
159
Table 1. Costs of producing perennial peanut (cv. ‘Florigraze’), annual peanut (cv. ‘Florida MDR 98’), cowpea (cv.
‘Iron clay’), pigeonpea (cv. ‘GA-2’), and soybean (cv. ‘Pioneer 97B52’) forage, hay, or haylage production in 2006
Seed or
sprig cost,
$
Seed or
sprig
rate/ ac
Initial
establishment
cost1, $/ac
Annual
maintenance
cost2, $/ac
Herbage
mass, tons
DM3/ac/yr
No. of
bales/
ac/yr4
Cost of
hay
baling5,
$/ac/yr
Cost of
Haylage
baling6,
$/ac/yr
Perennial
peanut
3.00/bu
80 bu
688
212
4.5
30
420
330
Annual
peanut
0.55/lb
18 lb
256
212
3.6
24
336
264
Cowpea
0.88/lb
50 kg
296
264
2.3
15
210
165
Pigeonpea
2.00/lb
50 kg
360
328
3.9
26
364
286
Soybean
0.88/kg
50 kg
296
264
3.8
25
350
275
Forage
1
Includes seed, fertilizer (290 lb/ac 0-20-40 ratio of N:P2O5:K2O), 1,600 lb/ac lime, herbicide, machinery, labor, and
estimated interest on monetary investment
2
Includes seed for cowpea, pigeonpea and soybean, fertilizer (290 kg/ha 0-20-40 ratio of N:P2O5:K2O), herbicide,
machinery, labor, and estimated interest on monetary investment, but not lime because it should be required every 2
to 3 yr
3
Dry matter (DM)
4
Estimated from small (300 lb) round bales utilized
5
Estimated from $14.00 charge per bale for twine, machinery, and labor
6
Estimated from $11.00 charge per bale for twine, plastic wrap, machinery, and labor
Equations from Hewitt, 2006 and Prevatt, 2008
Table 2. Net present value summary for perennial peanut (cv. ‘Florigraze’), annual peanut (cv. ‘Florida MDR 98’),
cowpea (cv. ‘Iron clay’), pigeonpea (cv. ‘GA-2’), and soybean (cv. ‘Pioneer 97B52’) forage, hay, or haylage production
over a 20-yr horizon
Hay production net
Haylage production net
Forage
present value1, $/ac
present value1, $/ac
Perennial peanut
3,728
4,596
Annual peanut
3,292
4,068
Jamie Foster
Cowpea
576
1,064
Adegbola Adesogan
Pigeonpea
2,664
3,520
Jeffrey Carter
Soybean
3,076
3,892
Lynn Sollenberger
1
Estimated rate of return after 20-yr using the value
of
income
Robert Myerand expense today. The greater the number, the greater
the return on investment after 20-yr.
Ann Blount
Expenses included 7% interest rate and $80 liming (1,600 kg/ha) in alternate yrs; profit included $37 value of 300 lb
round bale.
160
Figure 1. Changes in herbage mass (tons dry matter (DM)/ac) of cowpea, pigeonpea and soybean
abc
Means at each week after planting without a common superscript letter differ (P < 0.05).
Standard error of the mean = 0.42 tons DM/ac
5
a
4
Herbage mass (tons DM/ac)
Pigeonpea
Soybean
Cowpea
a
3
a
a
2
b
a
ab
b
1
b
c
b
0
0
5
10
15
Weeks after planting
20
25
Figure 2. Leaf-to-stem ratio of cowpea, pigeonpea, and soybean
abc
Standard error of the mean = 0.05
Pigeonpea
Soybean
Cowpea
1.4
Leaf-to-stem ratio
1.2
a
ab
1
a
b
b
0.8
b
0.6
a
a
b
b
b
b
a
b
0.4
0.2
0
5
10
15
161
20
25
Figure 3. Whole plant crude protein (CP) and neutral detergent fiber (NDF) concentrations (dry matter
(DM) basis) and in vitro true DM digestibility (IVTD) of cowpea, pigeonpea, and soybean
abc
Standard errors of the means for CP, NDF, and IVTD were 14, 18, and 17, respectively.
90
b)
NDF (% DM)
80
70
a
60
a
50
b
a
40
b
30
a
a
c
b
b
c
c
20
0
5
10
15
a) 30.0
a
CP (% DM)
25.0
a
b
20.0
b
10.0
5.0
0
IVTD (%)
5
a
ab
b
a
b
c
0
c
5
a
c
a
a
b
b
b
c
c
c
10
15
162
25
b
b
10
15
100
90
80
70
60
50
40
30
20
10
20
a
b
c
Pigeonpea
Soybean
Cowpea
25
a
a
b
b
15.0
c)
a
a
20
20
25
Case Study: Evaluation of Annual Cultivated Peanut as a Forage Crop for
Grazing by Growing Beef Cattle
Bob Myer1
Dan Gorbet
Ann Blount
Annual peanut forage like other forage legumes has excellent nutritional quality. However, it lacked
adequate re-growth during the grazing season when grazed by growing beef cattle.
Summary
The annual cultivated peanut (Arachic hypogaea
L.) was evaluated as a possible high quality
pasture forage crop for grazing by growing beef
cattle. A 10.2 ac field that was originally
planted to annual peanut in 1999 was used.
Since 1999, the peanut reseeded (self-seeded)
annually. The forage initially was harvested for
hay, and the seeds were left in the soil. In 2002,
a 2-yr demonstration grazing study was
initiated. Early weaned calves were used each
year – 25 (442 lb avg. wt.) for yr 1 and 20 (402
lb) for yr 2. The peanut field was rotationally
grazed each year starting mid July (yr 1) or
early August (yr 2). The relatively late start was
to ensure the peanut set seed for the next year’s
forage crop. The grazing season lasted 88 d for
yr 1 and 55 d for yr 2. Estimated average
forage yield was 5406 lb/ac and 3915 lb/ac for
yr 1 and 2, respectively. At the start of each
year, forage amount and quality was high;
however, both declined as grazing season
progressed. Estimated calf gain per ac was 165
and 94 lb for yr 1 and 2, respectively. The
annual peanut initially was an excellent forage
crop for grazing by early weaned beef calves,
but the lack of re-growth and declining forage
quality resulted in poor performance late in the
grazing periods.
southeastern USA. Temperate perennial forage
crops such as alfalfa (Medicago sativa) do not
grow well in this region (Prine and French,
1999). Perennial (rhizome) peanut for forage
(Arachis glabrata) can be grown in this area but
is planted from rhizomes and is hard and slow to
establish, taking two to three years to establish a
stand (Hill, 2002; French and Prine, 2006). The
cultivated or annual peanut (A. hypogaea) is
well adapted to this region and is established by
seed, and unlike the perennial peanut, forage
would be available the first year (Gorbet et al.,
1994).
Recent development of annual peanut cultivars
with resistance to late leaf spot may allow the
production of a quality, high yielding forage
crop without the use of fungicides. Fungicides
are commonly used in peanut production to
inhibit the development of late leaf, a common
foliar disease. Late leaf spot can decrease
amount of leaves and thus decrease forage
amount and nutritional quality. Also, there is an
inherent liability in feeding annual peanut forage
to livestock because many of the pesticides, in
particular, fungicides, used in peanut production
are not cleared for the feeding of forage and
crop residue (Gorbet et al., 1994; Hill, 2002).
Previous Florida research have obtained forage
dry matter yields of up to 7200 lb/ac using
disease resistance lines and without the use of
fungicides (Gorbet et al., 1994). In that study,
Introduction
High quality forage legumes that can be grown
during the warm season are scarce in the lower
163
the forage was harvested for hay 75 to 85 d after
planting and then the seed pods were harvested
at plant maturity. Defoliation of the canopy,
however, resulted in decreased seed pod yields.
an un-grazed check area. The four sections were
rotationally grazed starting in late July. This
rather late starting time was chosen to insure that
the peanut plants have “pegged” (seed set) for
re-seeding of the next year‟s forage crop. For the
first year, 25 early weaned heifers and steers
with an average initial weight of 442 ± 72 lb
were used. While grazing, the calves had free
access to water, mineral mix, and shade. Each
section was grazed for 7 d then allowed to
recover for 21 d and than grazed again. Three
complete cycles were completed. After the three
rotations, the cattle were allowed to graze all
sections for an additional 5 d.
With changes in the USA peanut program, there
has been interest in growing the annual peanut
strictly as a forage crop. Since the pods are not
harvested, the peanut plant may be able to selfseed (re-seed) and the plants would emerge the
next growing season to produce a subsequent
forage crop. Thus it would be possible to obtain
several years of forage from one planting.
Anecdotal evidence suggests that this may be
possible as annual peanut will readily emerge
(volunteer) the next spring from seed left after
harvest the previous fall. A 2-yr demonstration
study was conducted to evaluate the suitability
of annual peanut as a forage crop for grazing by
beef cattle.
Before grazing each section, the forage in two
representative one meter (1.2 sq. yd) square
areas was hand clipped to a stubble height of
about 5 in. Samples were taken to estimate
forage dry matter (DM) yield and determine
crude protein (CP) and in vitro organic matter
digestibility (IVOMD). The samples were dried,
ground (1 mm) and saved for future analyses.
Also, 7 d before the start in 2002 (yr 1) only, a
composite sample was taken from four
representative one meter square areas within the
entire field. This sample was dried, ground and
sent to commercial laboratory for the
determination of CP, phosphorus (P), calcium
(Ca), ash, acid detergent fiber (ADF), neutral
detergent fiber (NDF) and lignin.
The
individual section samples were dried, ground
and analyzed for CP and IVOMD.
Procedure
The 2-yr demonstration study was conducted at
the University of Florida‟s North Florida
Research and Education Center (NFREC)
Marianna Beef Unit located in northwest Florida
(30.5°N). A 10.2 ac field that was originally
planted with annual peanut (cultivar „Florida
MDR 98‟) in 1999 was used. Each year the
peanut plants emerged in April from seed of the
previous year‟s crop. For the first 3 yr, the
forage was harvested as hay. In 2002, a beef
cattle grazing study was started. The study was
conducted for two consecutive years without
replanting the annual peanut.
The above forage management and sampling,
and grazing procedures were repeated for the
second year (2003) except no lime was applied
to the field. Only 20 calves were used (avg.
initial weight of 402 ± 62 lb) for the second
year. For both years, calf weights were taken
after an overnight fast (no feed/pasture and
water) at start and end of grazing period, and at
an approximate midpoint (d 41 for yr 1 and d 32
for yr 2). For each year, the calves were
gradually adjusted to grazing of peanut forage
for 5 d prior to weighing and starting of the
grazing periods using a small section across the
ends of the four grazing sections. For the first
year, an initial cattle stocking density of 2.5
head/ac was chosen based on estimated available
forage. For the second year, the stocking rate
The peanut seeding rate in 1999 was 85 lb/ac.
Prior to the start of the grazing trial in 2002,
lime (dolomite, 1000 lb/ac) was applied to the
field in February. Fertilizer was applied (350
lb/ac of 9-24-16 + minor elements) during
March. Also during March, the field was treated
with herbicide (Sonalan, Dow AgroServices,
Indianapolis, IN, USA) and then disc harrowed.
The plants emerged in April. In May, the field
was sprayed with another herbicide (Cadre,
BASF Corp., Research Triangle, NC, USA).
During July, the field was divided into four
equal sized sections using temporary electric
fencing. A narrow section, 12 ft wide, through
the middle of the field was fenced off to provide
164
was lowered to 2.0 head/ac and time spent
grazing each section was also lowered to 4 d.
506 vs. 3,915 ± 285 lb/ac). Rainfall, however,
was more plentiful for yr 1 (Figure 2) which
may have resulted in the difference in forage
yield and also for the difference in length of
grazing period for each year.
The annual peanut was grown without fungicide
and under dry land conditions. Rainfall data
during each year‟s growing-grazing period was
obtained from the Florida Automated Weather
Network Station at NFREC Marianna.
Average daily gain (ADG) of the cattle was
consistent for the two yr and overall averaged
0.92 lb/d (Table3). However, during yr 1, an
ADG of 1.96 ± 0.60lb/d was obtained for the
first 41 d. A slightly negative gain was obtained
for the last 48 d. The decrease in performance
was probably due to the low forage yield and
poorer nutritional quality as the grazing period
progressed (Table 2; Figure 1).
Results
Initial analyses of the annual peanut forage
(Table 1) indicated very good nutritional value,
similar to that of alfalfa (NRC, 2000) and
perennial peanut (Prine and French 1999; Hill,
2000). Forage samples taken during the grazing
periods also indicated good nutritional value;
however, a noticeable decline occurred as the
grazing periods progressed, especially the first
year (Table 2).
Even though annual peanut was initially an
excellent forage source in each yr, its lack of regrowth was quite evident in each year‟s trial.
The strategy of lower initial cattle stocking
density and shorter grazing times per rotation
used during the second year appeared to be
somewhat successful. For the first yr, very few
leaves on the peanut plants were noted in a
section when the cattle were rotated to the next
section even though stubble height was 5 to 10
in. More leaves were evident in yr 2 with the
shorter rotations. Even though forage re-growth
declined as the grazing period progressed, the
decline noted for yr 2 was not as steep as noted
for yr 1 (Figure 1).
The estimated total DM yield of annual peanut
forage obtained during yr 1 was within the range
of forage yields obtained by Gorbet et al. (1994)
for the annual peanut (Table 3). Forage DM
yield; however, was lower than commonly
obtained (4 to 8 t/ac) for established perennial
peanut (Prine and French, 1999). Estimated
peanut forage DM yield declined noticeably as
each year‟s grazing period progressed,
especially in the first year (Figure 1). The
declines indicated a lack of re-growth.
Total calf weight gain per acre averaged 129
lb/yr in this study. Estimated costs for annual
peanut for pasture would be higher than value of
gain in calf weight. Even though some peanut
establishment costs can be spread out over 2 yr
or longer, estimated pasture costs still would be
about $120 to $140/ac per yr (Hewitt, 2006).
Since it appears that grazing may have a
negative impact on the following year‟s forage
yield, the probability of profitably would decline
with subsequent years.
Due to the declining peanut forage yield as the
grazing period progressed during yr 1, 11 calves
were removed after 41 d and the trial continued
with just 14 calves. For yr 2, all 20 were kept on
for the duration of the grazing period; however,
the grazing period lasted only 55 d vs. 88 d for
yr 1(Table 3).
The grazing season length each year was rather
short, especially the in yr 2 (Table 3). In
comparison, established perennial peanut can be
grazed for 110 to 140 d (June to mid-October)
per yr (Blount, A. R., personal communication).
Estimated forage DM yield overall was lower in
yr 2 and appeared to be negatively affected by
grazing in yr 1. Evidence for this negative affect
was that estimated DM forage yield obtained in
the un-grazed check strip was higher than
obtained in grazed areas during yr 2 (4,784 ±
In conclusion, the lack of re-growth limits the
annual peanut as a pasture crop for grazing at
this time. Progress via plant breeding may
produce high yielding, persistent, seeded peanut
cultivars that can be used for grazing over
several grazing seasons from a single planting.
Thus in the future, the annual peanut may be
165
viable high quality summer legume forage for
grazing in the southeastern USA.
Literature Cited
French, E.C. and G.M. Prine. 2006. UF-IFAS EDIS Publ. No. AA183.
Gorbet, D.W., et al. 1994. Peanut Sci. 21:112-115.
Hewitt, T. D. 2006. http://nfrec.ifas.ufl/hewitt/budgets.htm.
Hill, G.M. 2002. Vet. Clin. Food Anim. 18:295-315.
National Research Council (NRC). 2000. Nutrient Requirements of Beef Cattle, 7th Revised Ed.
National Academy Press. Washington, DC.
Prine, G. M., and E. C. French. 1999. Perspectives on New Crops and Uses. ASHS Press,
Alexandria, VA, USA. pp. 60-65.
Acknowledgment
The assistance of Mary Chambliss, Harvey Standland, Todd Matthews, Tina Gwin, John Crawford,
Wayne Branch, and Richard Fethiere is gratefully acknowledged. Partial funding was from Florida
Peanut Check-Off funds.
1
Bob Myer, Professor, Dan Gorbert, Professor Emeritus, and Ann Blount, Associate Professor; UFIFAS, North Florida Research and Education Center, Marianna, FL.
166
Table 1. Composition of annual peanut foragea
Item
Crude protein
Neutral detergent fiber
Acid detergent fiber
Lignin
Ash
Calcium
Phosphorus
a
Average of analyses of samples taken just prior to grazing in yr 1.
b
Dry matter basis.
%b
17.8
32.8
26.8
8.6
8.2
0.85
0.21
Table 2. Crude protein (CP) and in vitro organic matter digestibility (IVOMD) of annual
peanut forage during grazing trials.a
Year
1
2
a
Sampling period
First 28 d
Second 28 d
Last 33 d
CP,%
20.5
15.6
14.7
IVOMD,%
72
66
61
First 16 d
Second 16 d
Last 23 d
18.8
17.8
16.2
71
68
64
Average analyses of four samples per period per year; dry matter basis.
167
Table 3. Animal grazing days, forage dry matter (DM) yield, and performance of growing cattle grazing
annual peanut forage.a
Year 1
Year 2
Grazing period:
Start
12 Jul
5 Aug
End
8 Oct
29 Sep
Days
88
55
Grazing d/ac
167
113
Forage DM, lb/ac
5406 ± 148b
3915 ± 285b
Stocking density, head/ac
1.72
2.00
Avg. daily gain, lb
0.99 ± 0.42c
0.86 ± 0.29d
Gain, lb/ac
165
95
a
Yr 1, 25 head for first 41 d of grazing and 14 head for last 48 d of grazing. Yr 2, 20 head for entire
grazing period.
b
N = 4.
c
N = 19 (weighed average).
d
N = 20.
4000
3500
3000
2500
2000
Year 1
Year 2
1500
1000
500
0
First
Second
Last
Figure 1. Estimated annual peanut forage yield, lb dry matter/ac (First = first 28 d period of
grazing for yr 1 and first 16 d for yr 2; Second = second 28 d for yr 1 and second 16 d for yr 2;
and Last = last 33 d for yr 1 and last 23 d for yr 2; S.D. = 102, 112 and 46, and 73, 57 and 72 lb
DM/ac for each of the three periods for each yr, respectively).
168
Effects of Forage Sampling Method on Nutritive Value of Bahiagrass During
the Summer and Fall
Ashley Hughes1
Matt Hersom
This study suggests that when given the opportunity, cattle will selectively graze bahiagrass forage with
greater nutritive value than hand-collected forage during the summer and fall.
Summary
A six-mon trial was conducted from June to
November 2007 to evaluate the differences
between forage and masticate samples of
bahiagrass pastures at four research stations
across Florida (Ona, Brooksville, Santa Fe, and
Marianna) during the summer and fall. Eight
ruminally cannulated steers were used for
collection of masticate samples.
Forage
samples were collected by cutting the grass
within a 0.8-ft2quadrat to approximately 1-in
from the soil surface. High and low forage
availabilities were designated to represent
differences in forage quantities at each location.
Forage mass, in vitro digestible organic matter,
and crude protein concentrations were
determined for each sample type. There were
differences in forage mass, digestible organic
matter, and crude protein between locations, as
well as the state mean. The selection indices for
digestible organic matter at the four locations
were similar in value with a mean selection
index of 19% for all locations. However, the
selection indices for crude protein were much
more varied by location ranging from -11 to
47%. For most summer and fall months, steers
were able to select a diet that was greater in
digestibility and crude protein in comparison to
hand-collected forage samples.
commonly utilized forage in pasture grazing
systems in Florida occupying approximately 2.5
million ac (Chambliss and Sollenberger, 1991),
but also extends into the Gulf Coast Region.
Currently, there is little published data dedicated
to classifying subtropical forages on a yearround basis, whether by hand-sampling or
collection of masticate samples, with even less
data devoted to studying diet selection by cattle
grazing subtropical pastures.
Previous research has shown an inverse
relationship between maturity and quality of
grasses during the summer months (Connor et
al., 1963), while other studies have shown that
when adequate forage is available for grazing,
ruminants will selectively graze within those
situations (Weir and Torell, 1959; Schlegel et
al., 2000). When attempting to represent the diet
of a grazing animal, research has illustrated how
hand-collected forage samples are inaccurate in
their estimations of selected material (Coleman
and Barth, 1973; Russell et al., 2004). The
objective of this study was to characterize the
nutritive value of bahiagrass from four locations
across the state of Florida during the summer
and fall comparing sampling techniques, either
by hand-sampling or collection of masticate
sample, within pastures of varying levels of
forage availability (FA) with the ultimate goal of
better predicting available forage nutritive value
and subsequent supplementation needs to meet
Florida grazing cattle nutritional requirements.
Introduction
Florida pastures are comprised primarily of
tropical and subtropical grasses, which are
typically high yielding, but low in quality.
Bahiagrass (Paspalum notatum) is the most
169
(IVDOM), and crude protein (CP).
The
selection index (SI) for chemical composition
was also calculated using the following
equation, SI = {[(Masticate concentration –
hand-collected forage concentration) / handcollected forage concentration] * 100} + 100.
Four locations were utilized for this project to
represent the variation in the Florida pasture
landscape, the locations included: Range Cattle
Research and Education Center, Ona; USDASubtropical Agricultural Research Station,
Brooksville; Santa Fe River Ranch Beef Unit,
Alachua; and North Florida Research and
Education Center, Marianna. The pasture sizes
at each location were: 2.5 ac (Ona), 2.5 ac
(Brooksville), 2.0 ac (Alachua), and 3.7 ac
(Marianna). Bahiagrass (Paspalum notatum) was
the primary forage of interest for this trial.
However, there were different cultivars at each
location. At the Ona research site, the bahiagrass
cultivar used for the trial was Pensacola
(Paspalum notatum cv. Suarae Parodi), while
the cultivar found in Brooksville was primarily
Argentine bahiagrass, which is similar to
Pensacola, but may be more palatable. At the
Alachua research site, the bahiagrass cultivar
was Pensacola, while Marianna contained
Pensacola bahiagrass. The selected pastures
were managed at each location either by grazing
or mowing to allow for differences in available
forage mass. Pastures were not fertilized prior to
or during the trial.
Data were analyzed as a split plot design with
the whole plot completely randomized using the
MIXED procedure of SAS. The experimental
unit was steer or person for sample collection.
Fixed effects in the model included FA, month,
sampling type (masticate or hand-collection),
and their interactions. Repetition (steer or
person) within each FA was used for the
repeated measures and random effect. The least
squares means were determined. Means were
separated using the P-diff option when protected
by a significant F-value (P<0.05).
Results
Ona
At Ona, there were FA, month, and FA x month
interactions (P<0.05) for forage mass during the
summer and fall (Table 1). The forage mass of
the HIGH and LOW FA increased from June to
September with the high FA increasing nearly
13,500 lb/ac, whereas the low FA gained
approximately 1,000 lb/ac each month from June
to September. The HIGH and LOW FA
decreased in forage mass from September to
October with the HIGH FA gaining almost
3,000 lb/ac from October to November, while
the LOW FA decreased by approximately 1,500
lb/ac during the same time period. Masticate
samples were consistently greater (Table 2;
P<0.001) in IVDOM concentration by 12.8% on
average compared to hand-collected forage
samples.
Month also affected (P<0.001)
IVDOM of both masticate and hand-collected
samples. The variation between sample type
and month (P<0.001) affected IVDOM
concentration during the summer and fall.
Likewise, the CP concentration of masticate
samples (Table 3; P<0.001) averaged 3.2%
greater than hand-collected forage samples
during the summer and fall with the exception of
July, which may have been influenced by the
start of the summer growing season. As a result
of the similar CP concentration of forage and
masticate samples in July, a type x month
Forage and masticate samples were collected
monthly (approximately every 30 d) from June
to November 2007. Eight ruminally cannulated
Angus or Brangus steers were used for this
experiment with two steers at each location (one
Angus and one Brangus) for collection of
masticate samples. Forage availabilities were
visually assigned to the selected pastures, as
either HIGH or LOW, at each location to
represent differences in forage quantity. Within
each pasture, two individuals hand-clipped three
forage samples each for a total of six samples
per pasture. Hand shears were used to cut the
forage within a 0.8-ft2 quadrat to an approximate
height of 1-in from the soil surface.
Simultaneously, masticate samples were
collected from the fistulated steers by initially
emptying the rumen, allowing the steers to graze
either the HIGH or LOW FA pasture for
approximately one hour, then removing the
selected material from the rumen. Forage and
masticate samples were analyzed for forage
mass, in vitro digestible organic matter
170
(P=0.03) effect was observed. Crude protein
concentration of both masticate and forage
samples (P<0.001) decreased from June to
August. Forage CP concentration of both
sampling types increased during September, yet
decreased for the remainder of the fall season.
The mean SI for Ona indicated an opportunity
for selection of forage material that was 30%
greater in IVDOM concentration and 28%
greater in CP concentration compared to handcollected forage values (Table 4).
Santa Fe
Similar to Brooksville and Marianna, forage
mass at SF (Table 1) was affected by FA
(P=0.02), month (P<0.001). The FA x month
interaction (P<0.001) was likely due to the
similarity in results of the HIGH and LOW FA
during October. The hand-collected forage
decreased in IVDOM concentration (Table 2)
from June (59.2%) to August (49.2%) yet
increased in September (58.0%) and October
(62.6%) and decreased during November
(48.0%). The IVDOM concentration of the
masticate samples varied little during the
summer and fall with the exception of the lower
nutritive value seen in June and November.
However masticate samples were greater in
IVDOM concentration compared to handcollected forage samples with the exception of
June. Crude protein concentration of handcollected forage and masticate samples varied
considerably during the summer and fall (Table
3) resulting in type and month effects (P<0.001),
as well as a type x month interaction (P<0.001).
The steers were able to select forage material
that was 26% greater in IVDOM concentration
during July and 40% greater in CP concentration
during July with the other months eliciting less
of a selection response (Table 4).
Brooksville
There were no samples taken in July at the
Brooksville location, because of sampling
difficulties that month. During the remaining
summer months, while there were significant FA
and month effects (P=0.05 and P=0.009,
respectively), there was no FA x month
interaction (P<0.001) for forage mass at
Brooksville (Table 1). Brooksville increased in
forage mass from June to October with a slight
decrease in mass during September and
November. The FA and month effects were
likely influenced by the almost 10,500 lb/ac gain
in forage mass from June to October for HIGH
FA, while the LOW FA gained nearly 4,800
lb/ac during the same time period. The forage
mass of the HIGH FA was 50% greater than the
LOW FA in October. There was a sample type
effect for IVDOM concentration (Table 2;
P<0.001) and sample type and month effects
(Table 3; P<0.001) for CP concentration during
the summer and fall. The steers were consistent
in their selection of forage material, which
resulted in the masticate IVDOM samples
varying by less than 1% from June to November,
while the hand-sampled forage IVDOM changed
6% during the sampling period. There was an
inverse relationship between forage mass and
CP concentrations of masticate and handcollected forage samples during the summer and
fall. The mean concentrations of IVDOM and
CP were greater for masticate compared to handcollected forage samples, which resulted in SI
that were 15% greater in IVDOM concentration
and 26% greater in CP concentration during the
summer and fall (Table 4).
Marianna
Marianna experienced gains in forage mass in
HIGH and LOW FA from June to September
with FA (P=0.05) and month (P<0.001) effects,
yet forage mass decreased during the remaining
months (Table 1). The masticate IVDOM
concentration differed between sampling type,
as well as between months (P<0.001).
Masticate sample IVDOM concentration (Table
2) was greater (mean= 63%) than hand-collected
forage samples (mean= 53%) from June to
November. The CP concentration of handcollected forage and masticate samples (Table 3)
were similar in value during each month of the
summer and fall (P<0.001) with the exception of
July and August. The selection indices (Table 4)
indicate that the steers were able to select forage
that was 16% greater in IVDOM concentration
than hand-collected forage values during the
171
summer and fall. The steers were also able to
select forage that was 30% greater in CP
concentration during July and 48% greater in CP
concentration during August compared to handcollected forage with the other months eliciting
less of selection response.
November.
Similar
to
IVDOM,
CP
concentration of masticate samples were
consistently greater (P<0.001) than those of the
hand-collected forage samples except in June.
During this study, regardless of forage mass,
steers selected forage material (Table 4) that was
about 19% greater in IVDOM concentration on
average compared to hand-collected forage
samples. While there were no differences
between month (P=0.16) in SI for CP
concentration, there was no selection in June
(-3%), while the other summer and fall months
had a mean SI of 25%.
State Mean
Forage mass (Table 1) was affected by month
(P<0.001) and FA (P=0.03), while there was a
tendency for a FA x month effect (P=0.06). All
locations experienced either a decrease or no
change in DMY from May to June with forage
DMY not increasing until the latter end of the
summer. Both HIGH and LOW FA increased in
forage mass from June to September, when
yields began to decline. The FA x month trend
was likely influenced by the simultaneous gains
and losses of forage mass for the HIGH and
LOW FA during the trial. Masticate samples
were consistently greater (Table 2; P<0.001) in
IVDOM concentration compared to handcollected forage samples, averaging 9% greater
IVDOM concentration during the summer and
fall. Steers were consistent in their selection of
forage material, in that masticate IVDOM
concentration only varied by 3% during the
summer, while the hand-collected forage
IVDOM concentration changed 11% during the
sampling period.
Month affected CP
concentration of hand-collected forage and
masticate samples (Table 2; P<0.001) during the
summer and fall, resulting in a type x month
interaction (P<0.001). The lack of rainfall in
May and June may have influenced forage mass,
as well as hand-collected forage chemical
composition variation between months. At most
locations, precipitation was less than the 30-yr
average for all locations from May to
Conclusions and Implications
The results of this study indicate that while
bahiagrass matures and its forage mass
increases, grazing steers will select forage
material with greater IVDOM and CP
concentrations. When given the opportunity,
cattle grazing bahiagrass forage will select a diet
that is greater in nutritive value compared with
hand-collected samples, which are normally
gathered for estimation of available forage
quality. The data collected in this study imply
that forage samples collected by hand may
under-estimate the nutritive value of the actual
selected forage by cattle. The implications of
this study indicate the opportunity to more
closely match cow requirements with forage
resources, based on available bahiagrass
nutritive value and cow selection within those
forage opportunities. If energy and protein
supplementation can be more closely matched to
cow requirements, then less N and other nutrient
inputs would be added to the environment thus
improving land and water quality, which is an
important concern for Florida cattle producers.
Literature Cited
Chambliss, C. G. and L. E. Sollenberger. 1991. Proc. 40 th Annual Florida Beef Cattle Short Course, pp 74-80.
Coleman, S. W. and K. M. Barth. 1973. J. Anim. Sci. 36: 754-761.
Connor, J. M. et al. 1963. J. Anim. Sci. 22: 961-969.
Russell, J. R. et al. 2004. J. Anim. Sci. 82(Suppl 2): 93.
Schlegel, M. L. et al. 2000. J. Anim. Sci. 78: 2202-2208.
Weir, W. C. and D. T. Torell. 1959. J. Anim. Sci. 18:641-649.
Ashley Hughes, Former Graduate Student; Matt Hersom, Assistant Professor, UF-IFAS, Animal
Sciences, Gainesville, FL
1
172
Table 1. Effect of forage availability and month on overall mean forage mass (lb/ac)
Month
FAa
June July
Aug
Sept
Oct
Nov
SEMd
b
H
3,838 5,396 10,513 17,328 13,109 15,861 1,679
Lc
2,697 3,644 4,979 5,469 4,990 3,392
Brooksville H
972
na
8,689 8,446 11,457 10,643 1,555
L
958
na
5,175
3,718 5,767 4,038
Santa Fe
H
3,196 4,418 4,767 8,825 3,420 3,245
392
L
1,346 3,528 3,596 2,647 3,318 2,254
Marianna
H
1,164 2,750 8,575 8,378 8,110 3,443
874
L
836 2,110 3,743 5,728 5,210 2,212
St. Mean
H
2,292 4,187 8,142 10,745 9,024 8,298 1,029
L
1,459 3,094 4,373 4,390 4,823 2,976
a
FA= Forage availability.
b
H= High forage availability.
c
L= Low forage availability.
d
SEM= Standard error of the mean, n=12.
Location
Ona
P-value
FA Month FA*Mo
0.02 0.005
0.03
0.05 0.009
0.33
0.02 <0.001
<0.001
0.05 <0.001
0.18
0.03 <0.001
0.06
Table 2. Effect of sampling type and month on in vitro digestible organic matter (IVDOM, %)
Typea
June
July
Fb
48.69 50.91
Mc
54.90 56.59
Brooksville F
54.18
na
M
61.39
na
Santa Fe
F
59.23 52.23
M
53.46 59.09
Marianna
F
55.82 50.41
M
63.97 67.69
St. Mean
F
54.51 51.23
M
58.42 61.11
a
Type= Forage sampling type.
b
F= Hand-sampled forage.
c
M= Masticate.
d
Location
Ona
Month
Aug
Sept Oct
44.33 43.67 51.63
56.96 68.13 69.53
48.07 54.64 49.65
59.74 62.33 61.31
49.02 57.98 62.64
61.87 63.45 61.73
50.87 61.49 56.15
64.12 64.12 61.33
48.12 54.92 55.04
60.74 64.51 63.42
173
Nov
SEMd
45.11
1.31
59.74
45.59
2.08
51.21
47.99
1.84
55.67
46.09
1.43
59.33
46.24
1.47
56.51
P-value
Type
Month Type*Mo
<0.001 <0.001
<0.001
<0.001
0.009
0.42
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
0.08
Table 3. Effect of sampling type and month on crude protein (CP, %)
Typea
June July
b
F
9.83
8.86
Mc
10.08
8.69
Brooksville F
12.24
na
M
13.34
na
Santa Fe
F
15.35
9.70
M
11.64 13.70
Marianna
F
17.30 10.58
M
16.72 13.65
St. Mean
F
13.91
9.73
M
12.92 12.11
a
b
F= Hand-sampled forage.
c
M= Masticate.
d
Location
Ona
Month
Aug
Sept Oct
Nov
SEMd
6.87
8.77
7.25
7.53
0.45
8.57 12.57 11.10 10.65
8.39
6.93
7.69
6.89
0.42
10.92
9.86 10.37
9.49
10.62 10.62 10.16
8.69
0.29
12.00
8.98 11.49
9.98
8.82
8.48
9.41 10.00
0.43
12.87
8.83 10.62 10.49
8.62
8.64
8.64
8.32
0.62
11.03
9.61 10.71 10.13
P-value
Type
Month
Type*Mo
<0.001
<0.001
0.004
<0.001
<0.001
0.17
0.004
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
Table 4. Effect of month on steer selection indexa of bahiagrass forage.
Month
Analysis June
July
Aug
Sept
Oct
Nov
SEMd P-value
b
IVDOM 113.76 111.15 129.22 157.49 136.13 132.01
8.06
0.07
CPc
103.50 97.23 123.75 148.46 153.15 141.47 18.71
0.31
Brooksville IVDOM 113.29
.
124.29 110.38 123.32 112.33
3.16
0.09
CP
108.97
.
129.94 142.12 135.50 137.70 10.18
0.32
Santa Fe
IVDOM
90.79 113.14 126.00 109.53
98.78 116.17
6.64
0.09
CP
79.07 140.93 112.21
86.90 113.05 115.47 15.24
0.21
Marianna
IVDOM 115.83 134.53 126.02 104.03 107.78 128.12 12.84
0.55
CP
96.82 130.03 147.61 104.75 111.63 103.71 10.13
0.09
St. Mean
IVDOM 108.42 119.63 126.42 120.41 116.53 122.21
6.08
0.43
CP
97.11 122.73 128.44 120.62 128.34 124.63
8.99
0.16
a
{[(Masticate concentration – forage concentration) / forage concentration] * 100} + 100.
b
IVDOM= In vitro digestible organic matter.
c
CP= Crude protein.
d
Location
Ona
174
Effects of Forage Sampling Method on Nutritive Value of Bahiagrass During
the Winter and Spring
Ashley Hughes1
Matt Hersom
This study suggest that when adequate forage is available for grazing, steers will selectively graze
bahiagrass forage with greater nutritive value than hand-collected forage during the winter and spring.
Summary
A six-mo trial was conducted from December
2006 to May 2007 to evaluate the differences
between forage and masticate samples of
bahiagrass pastures at four research stations
across Florida (Ona, Brooksville, Santa Fe, and
Marianna) during the winter and spring. Eight
ruminally cannulated steers were used for
Forage
samples were collected by cutting the grass
within a 0.8-ft2quadrat to approximately 1-in
from the soil surface. High and low forage
availabilities were designated to represent
differences in forage quantities at each location.
Forage mass, in vitro digestible organic matter,
and crude protein concentrations were
determined for each sample type. There were
differences in forage mass, digestible organic
matter, and crude protein between locations, as
well as the state mean.. Selection indices
indicated the opportunity for selection of forage
that was greater in digestibility and crude
protein compared to hand-collected forage
samples. The selection indices for digestibility
were similar at the four locations varying from 0
to 62%, while the selection indices for CP
differed more by location ranging from -4 to
68%. Overall, during the winter and spring,
steers were able to select a diet that was 31%
greater in digestibility and 21% greater in crude
protein compared to hand-collected forage
samples.
of tropical and subtropical grasses, which are
typically high yielding, but low in quality.
Bahiagrass (Paspalum notatum) is the most
commonly utilized forage in pasture grazing
systems in Florida occupying approximately 2.5
million ac (Chambliss and Sollenberger, 1991),
but also extends into the Gulf Coast Region.
Currently, there is little published data dedicated
to classifying subtropical forages on a yearround basis, whether by hand-sampling or
collection of masticate samples, with even less
data devoted to studying diet selection by cattle
grazing subtropical pastures.
Studies have shown that when adequate forage is
available for grazing, ruminants will selectively
graze within those situations (Weir and Torell,
1959; Schlegel et al., 2000). When attempting
to represent the diet of a grazing animal,
research has illustrated how hand-collected
forage samples are inaccurate in their
estimations of selected material (Coleman and
Barth, 1973; Russell et al., 2004). The objective
of this study was to characterize the nutritive
value of bahiagrass from four locations across
the state of Florida during the winter and spring
comparing sampling techniques, either by handsampling or collection of masticate sample,
within pastures of varying levels of forage
availability (FA) with the ultimate goal of better
predicting available forage nutritive value and
subsequent supplementation needs to meet
Florida grazing cattle nutritional requirements.
Introduction
Florida pastures are comprised primarily
175
forage mass, in vitro digestible organic matter
(IVDOM), and crude protein (CP).
The
selection index (SI) for chemical composition
was also calculated using the following
equation, SI = {[(Masticate concentration –
hand-collected forage concentration) / handcollected forage concentration] * 100} + 100.
Four locations were utilized for this project to
represent the variation in the Florida pasture
landscape, the locations included: Range Cattle
Research and Education Center, Ona; USDASubtropical Agricultural Research Station,
Brooksville; Santa Fe River Ranch Beef Unit,
Alachua; and North Florida Research and
Education Center, Marianna. The pasture sizes
at each location were: 2.5 ac (Ona), 2.5 ac
(Brooksville), 2.0 ac (Alachua), and 3.7 ac
(Marianna). Bahiagrass (Paspalum notatum) was
the primary forage of interest for this trial.
However, there were different cultivars at each
location. At the Ona research site, the bahiagrass
cultivar used for the trial was Pensacola
(Paspalum notatum cv. Suarae Parodi), while
the cultivar found in Brooksville was primarily
Argentine bahiagrass, which is similar to
Pensacola, but may be more palatable. At the
Alachua research site, the bahiagrass cultivar
was Pensacola, while Marianna contained
Pensacola bahiagrass. The selected pastures
were managed at each location either by grazing
or mowing to allow for differences in available
forage mass. Pastures were not fertilized prior to
or during the trial.
Data were analyzed as a split plot design with
the whole plot completely randomized using the
MIXED procedure of SAS. The experimental
unit was steer or person for sample collection.
Fixed effects in the model included FA, month,
sampling type (masticate or hand-collection),
and their interactions. Repetition (steer or
person) within each FA was used for the
repeated measures and random effect. The least
squares means were determined. Means were
separated using the P-diff option when protected
by a significant F-value (P<0.05).
Results
Ona
At Ona, there was a month effect (Table 1;
P<0.001), whereas there was only a tendency for
a FA effect (P=0.09). Ona had significantly
greater forage mass in comparison to the other
locations. The high FA decreased steadily
during the winter months until a 4,500 lb/ac
increase in May, whereas the low FA remained
fairly similar during the winter until a 4,000
lb/ac increase in May.
The IVDOM
concentration of masticate samples (Table 2)
were greater (P<0.001) than hand-collected
forage samples during the winter and spring.
Month also affected IVDOM concentration
(P<0.001) of forage and masticate samples, as
both sample types steadily increased in IVDOM
concentration during the winter. Likewise, the
CP concentration of masticate samples (Table 3)
was greater (P<0.001) compared to handcollected forage samples with exception of
March, which likely caused the type x month
effect (P<0.001). The mean SI at Ona (Table 4)
indicated that the steers were selecting forage
31% greater in IVDOM concentration and 21%
greater in CP concentration compared to handcollected forage samples during the winter and
spring months.
Forage and masticate samples were collected
monthly (approximately every 30 d) from
December 2006 to May 2007. Eight ruminally
cannulated Angus or Brangus steers were used
for this experiment with two steers at each
location (one Angus and one Brangus) for
Forage
availabilities were visually assigned to the
selected pastures, as either HIGH or LOW, at
each location to represent differences in forage
quantity. Within each pasture, two individuals
hand-clipped three forage samples each for a
total of six samples per pasture. Hand shears
were used to cut the forage within a 0.8-ft2
quadrat to an approximate height of 1-in from
the soil surface. Simultaneously, masticate
samples were collected from the fistulated steers
by initially emptying the rumen, allowing the
steers to graze either the HIGH or LOW FA
pasture for approximately one h, then removing
the selected material from the rumen. Forage
and masticate samples were analyzed for
176
Brooksville
There were no differences in forage mass at
Brooksville (Table 1) between FA (P=0.23) or
month (P=0.15) during the winter and spring.
While the IVDOM concentration of both sample
types (Table 2) increased from December to
May (P<0.001), masticate samples averaged
13% greater IVDOM concentration (P<0.001)
compared to hand-collected forage samples.
Similarly, the CP concentration of masticate
samples (Table 3) was greater (P<0.001) than
the hand-collected samples during the winter
and spring. The similarity of the forage and
masticate CP concentrations in March led to a
type x month (P<0.001) effect. At Brooksville,
the steers were able to select forage that was
32% greater in IVDOM and CP compared to
hand-collected forage samples (Table 4).
greater in CP concentration (36% and 22%,
respectively) with other months eliciting less of
a selection response.
Marianna
Marianna had the lowest forage mass (Table 1)
compared with other locations, with variation
between months (P=0.04), but not between FA
(P=0.12).
Masticate sample IVDOM
concentration (Table 2) was greater (P<0.001)
compared to hand-collected forage samples with
variation between months (P<0.001). With the
exception of January (35.0% IVDOM
concentration), hand-collected forage samples
varied by less than 5% IVDOM (mean= 53.0%).
Similarly, IVDOM concentration of masticate
samples only varied by 9% during the winter
and spring (mean= 64.3%) with the exception of
January (54.5%). The differences between
sample type and month resulted in a type x
month
(P=0.03)
effect
for
IVDOM
concentration during the winter and spring.
Masticate sample CP concentrations (Table 3)
were greater (P<0.001) than hand-collected
forage samples from December to May. CP
concentrations were also affected by month
(P<0.001) with only a tendency for a type x
month interaction (P=0.08), which was likely
due to the similarity in value between masticate
and hand-collected forage samples during
March. The greatest opportunity for selection of
forage with greater IVDOM concentration
compared to hand-collected forage (Table 4;
P<0.05) was in January (55.4%) and February
(37.3%). The mean SI for CP concentration
indicated the opportunity for selection of forage
material that was 17% greater in CP
concentration compared to hand-collected forage
during the winter and spring.
Santa Fe
There was no LOW FA sample taken at Santa Fe
during January due to sampling difficulty, thus
forage and masticate samples were not analyzed
for IVDOM and CP during January. There was
a month effect (P=0.04) for forage mass from
December to May, which was likely due to the
sharp increase in forage mass in May with only a
tendency (P=0.09) for a difference between FA
(Table 1). Throughout the winter and spring,
IVDOM concentration (Table 2) was greater
(P<0.001) for masticate compared to handcollected samples. Month also affected IVDOM
concentration of both sample types (P<0.001)
from December to May. The variation between
sample type and month led to type x month
(P=0.01) interaction for IVDOM concentration.
During the winter and spring, CP concentration
(Table 3) varied between month (P<0.001).
While there was no sample type effect (P=0.18)
on CP concentration, masticate samples had
greater CP concentration than hand-collected
forage samples with the exception of March.
February had the greatest SI (Table 4) for
IVDOM concentration (P<0.05) indicating the
opportunity for steer selection of forage 62%
greater in IVDOM concentration compared to
hand-collected forage samples with other
months eliciting less of a selection response
(mean= 14%). During January and February,
the steers were able to select forage that was
State Mean
Month affected the overall state mean forage
mass (Table 1; P<0.001), while there only
tended to be a difference between FA (P=0.10)
at all locations. The forage mass of the HIGH
FA decreased from December to April until
increasing in May, while the LOW FA remained
fairly constant during the winter until increasing
by approximately 1,400 lb/ac in May. Masticate
177
samples were consistently greater (mean=
59.2%) in IVDOM concentration (Table 2;
P<0.001) compared to hand-collected forage
samples (mean= 45.8%). Month also affected
IVDOM concentration of masticate and handcollected forage samples (P<0.001) during the
winter and spring likely due to changing
environmental factors at each location. The
sample type and month effects led to a type x
month interaction (P<0.001) for IVDOM
concentration. Similarly, CP concentrations
(Table 3) were affected by month (P<0.001)
with masticate samples consistently greater than
the hand-collected forage samples with the
exception of March, thus influencing a type x
month interaction (P=0.02). The SI for IVDOM
concentration (Table 4) varied by month
(P<0.05) with the greatest opportunity for
selection in January and February (51%), while
the remaining months indicated the steers
selected forage that was 19% greater in IVDOM
concentration compared to hand-collected forage
samples. The SI for the overall mean CP
concentration (P<0.05) was greatest in
December (37%), followed by January and
February (30%), and least in March, April and
May (10%) indicating less of an opportunity for
selection of forage as the winter and spring
seasons progressed.
Conclusions and Implications
The results of this study indicate that during the
winter and spring when bahiagrass forage mass
is most limiting and nutritive value is low,
grazing steers will select forage material with
greater IVDOM and CP concentrations
compared to hand-collected forage values,
which are normally gathered for estimation of
available forage quality. The data collected in
this study imply that forage samples collected by
hand may under-estimate the nutritive value of
the actual selected forage by cattle.
The
implications of this study indicate the
opportunity to more closely match cow
requirements with forage resources, based on
available bahiagrass nutritive value and cow
selection within those forage opportunities. If
energy and protein supplementation can be more
closely matched to cow requirements, then less
N and other nutrient inputs would be added to
the environment thus improving land and water
quality, which is an important concern for
Florida cattle producers.
Literature Cited
Chambliss, C. G. and L. E. Sollenberger. 1991. Proc. 40th Annual Florida Beef Cattle Short Course, pp 7480.
Coleman, S. W. and K. M. Barth. 1973. J. Anim. Sci. 36: 754-761.
Russell, J. R. et al. 2004. J. Anim. Sci. 82(Suppl 2): 93.
Schlegel, M. L. et al. 2000. J. Anim. Sci. 78: 2202-2208.
Weir, W. C. and D. T. Torell. 1959. J. Anim. Sci. 18:641-649.
1
Ashley Hughes, Former Graduate Student; Matt Hersom, Assistant Professor, UF-IFAS, Animal
Sciences, Gainesville, FL
178
Table 1. Effect of forage availability and month on overall mean forage mass (lb/ac)
FAa Dec
Jan
Hb
5,184 3,429
Lc
1,858 1,195
Brooksville H
2,093 1,277
L
1,431
833
Santa Fe
H
1,626 1,000
L
939
na
Marianna
H
1,128 1,616
L
406
478
St. Mean
H
2,508 2,832
L
1,159
836
a
FA= Forage availability.
b
H = High forage availability.
c
L= Low forage availability.
d
SEM= Standard error of the mean.
Location
Ona
Feb
3,156
1,257
2,251
951
1,345
867
889
672
1,911
937
Month
Mar
2,653
1,341
1,974
1,366
1,311
930
730
703
1,085
1,376
Apr
1,840
978
1,329
1,114
1,170
946
927
519
889
1,316
May SEMd
6,258
592
4,017
1,788
356
1,259
3,549
383
1,466
1,872
275
1,386
2,032
414
2,700
P-value
FA Month FA*Month
0.09 <0.001
0.17
0.23
0.15
0.50
0.09
0.02
0.19
0.12
0.04
0.42
0.10
0.001
0.73
Table 2. Effect of sampling type and month on in vitro digestible organic matter (IVDOM, %)
Typea Dec
Jan
Feb
Fb
38.56 34.94 39.09
Mc
47.80 51.17 58.41
Brooksville F
40.43 39.69 38.73
M
52.44 60.08 58.78
Santa Fe
F
43.66
na
39.32
M
51.46
na
63.27
Marianna
F
54.68 35.04 50.80
M
66.34 54.56 69.51
St. Mean
F
44.21 37.51 42.24
M
55.63 56.32 62.62
a
b
F= Hand-collected forage.
c
M= Masticate.
d
Location
Ona
Month
Mar
42.83
56.45
44.36
56.62
55.84
63.63
54.88
61.99
49.62
60.63
179
Apr
43.70
65.25
50.26
57.89
51.81
57.08
54.49
60.15
50.81
59.84
May SEMd
51.29
2.05
58.72
50.10
1.42
57.78
50.42
2.62
61.57
50.19
2.23
63.65
50.52
1.98
60.53
P-value
Type
Month Type*Month
<0.001 <0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
0.01
<0.001
<0.001
0.06
<0.001
<0.001
<0.001
Table 3. Effect of sampling type and month on crude protein (CP, %)
Location
Ona
a
Type Dec
Jan
Feb
Fb
7.57
9.22 10.93
Mc
9.57 10.56 13.49
Brooksville F
6.78
8.02
8.06
M
10.19 12.90 11.47
Santa Fe
F
7.70
na
11.91
M
9.83
na
14.56
Marianna
F
9.03
9.75 12.16
M
12.00 11.70 14.24
St. Mean
F
7.81
9.53 10.82
M
10.62 11.94 13.44
a
b
F= Hand-collected forage.
c
M= Masticate.
d
Month
Mar
Apr
May
SEMd
12.05 11.70 10.84
0.62
11.92 15.72 12.24
10.20 10.06 10.89
0.49
10.39 11.63 11.63
15.20 13.75 13.27
0.89
14.72 15.07 13.55
10.36 11.47
9.83
0.56
10.57 11.89 12.61
11.92 11.72 11.31
0.58
11.93 13.64 12.52
P-value
Type
Month Type*Month
<0.001 <0.001
<0.001
<0.001
<0.001
<0.001
0.18
<0.001
0.43
<0.001
<0.001
0.08
<0.001
<0.001
0.02
Table 4. Effect of month on steer selection indexa of bahiagrass forage.
Location
Analysis
Month
Dec
Jan
Feb
Mar
Apr
May
Ona
IVDOMb 122.73 146.45
153.78
129.85 149.22
115.12
CPc
124.98 118.66
134.53
99.91 136.43
112.88
Brooksville IVDOM 129.68 151.72
151.79
127.67 115.74
116.70
CP
150.24 167.84
147.56
101.84 115.55
106.71
Santa Fe
IVDOM 108.78
na
161.63
114.36 110.47
122.25
CP
136.06
na
122.17
96.84 109.80
102.08
Marianna
IVDOM 121.72 155.43
137.30
112.87 104.30
126.98
CP
134.69 118.00
116.28
102.07 103.91
129.38
St. Mean
IVDOM 120.71g 151.82ef 151.11e 121.23g 119.92g 120.34g
CP
136.52f 131.03f
130.12f 100.24e 116.44ef 112.82ef
a
{[(Masticate concentration – forage concentration) / forage concentration] * 100} + 100.
b
IVDOM= In vitro digestible organic matter.
c
CP= Crude protein.
d
e,f,g
Within a row, means with a different superscript differ, P<0.05
180
SEMd P-value
18.96
0.65
24.93
0.89
6.72
0.04
19.55
0.24
6.18
0.02
21.34
0.79
8.11
0.05
8.96
0.21
5.73 <0.001
8.59
0.03
Research and Graduate Programs
Undergraduate Programs
The Department offers four animal industry
options (Beef, Meats, Equine, and Dairy), plus an
Animal Biology Specialization which serves preprofessional students. The Beef Cattle option is
designed for students wanting to pursue a career
in the beef cattle industry. This option prepares
students in the area of management, genetic
improvement,
feeds
and
feeding,
and
reproduction.
Potential
careers
include;
management, marketing and sales, genetics,
laboratory and quality control.
The Department has 31 faculty members
working in the various disciplines of
Nutrition,
Breeding
and
Genetics,
Physiology, Molecular Biology, Meat
Science and Management. Additionally,
there are several faculty members at the outlying Research and Education Centers that
participate in our research and graduate
programs. The Department offers programs
in Master of Science, Master of Agriculture
and Doctor of Philosophy.
Resources
Students have access to an on-campus beef
teaching cow herd in addition to two research
and production–oriented herds close to campus.
There are also three additional out-lying
Research and Education Centers with over
2,500 beef cows of both Bos indicus and Bos
taurus breeding available for research and to
provide hands-on experience for our students.
Extension and the Beef Industry
The Department plays an active role in
facilitating communication and dissemination
of research and production-oriented material to
Florida cow-calf producers. Beef producers
and state and county faculty work cooperatively
in an effort to improve the production,
efficiency and marketability of Florida beef
cattle. Florida is in a unique position of having
more large-scale cow-calf operations than any
other state in the United States.

2009 Florida Beef Research Report

Transcription

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