Noviembre 2011 - FMVZ-UNAM

Transcription

AÑO 5 *
NUMERO 51 * NOVIEMBRE 2011
http://www.fmvz.unam.mx/fmvz/departamentos/reproduccion/boletin/actual.html
Noviembre 2011
1
“Antes muerta que sencilla”
En los hatos lecheros se desecha cada año de 30 a 40% de las vacas adultas, lo cual obliga a producir una
cantidad similar de vaquillas, para mantener una población constante de vacas en ordeño. La vida
productiva de una vaca es de 2.5 a 3.5 lactancias, lo que indica que muy pocas vacas llegan a la cuarta o
quinta lactancias, cuando se alcanza la mayor producción de leche. Con fines descriptivos se han dividido
las causas de desecho en involuntarias y voluntarias. El primer grupo incluye enfermedades, infertilidad,
muerte; y el segundo grupo, la baja producción (lactancias cortas) y criterios raciales. Las principales causas
de desecho involuntario son infertilidad, mastitis, problemas del aparato locomotor y enfermedades
metabólicas. La mayor parte de los desechos ocurre durante los primeros 100 días posparto, en este
periodo de la lactancia ocurre cerca de la mitad de los desechos totales. En los primeros 30 días posparto
se eliminan de 6 a 10% de las vacas paridas, ya sea por enfermedad o muerte, lo cual está directamente
relacionado al manejo realizado en el periodo de transición. Algunos problemas reproductivos aumentan el
riego de desecho, por ejemplo, distocia, retención de placenta, quistes ováricos, metritis y periodos largos
de anestro posparto. El porcentaje de vacas eliminadas por razones involuntarias ha aumentado en los
últimos años, lo cual está asociado con el aumento del número de vacas por hato, con la alta producción de
leche (en los últimos 40 años pasó de 5 mil kg a más de 10 mil kg por lactancia), y con los sistemas de
alimentación basados en dietas con alto contenido energético, sólo por mencionar algunos factores. Manejar
vacas con producciones de >10 mil kg equivale a conducir un auto a más de 200 km por hora, en donde una
distracción tiene consecuencias fatales. En estas vacas cualquier cambio en los ingredientes en la dieta,
falla en el mezclado, un día con lluvia, un día caluroso, trabajadores nuevos, fin de semana, o la fiesta del
pueblo, tiene consecuencias no solo en la producción de leche sino también en la tasa de desechos. Cabe
recordar que la vaca lechera moderna es producto de muchos años de selección genética en conjunción
con el mejoramiento continuo de las prácticas de ordeño, alimentación, confort, salud y reproducción. La
complejidad metabólica de la vaca lechera requiere de un manejo altamente especializado y cualquier
carencia tiene consecuencias negativas en la duración de su vida productiva.
Foto de Portada. Feminización del trabajo profesional en el ganado lechero (prácticas de reproducción bovina en la
cuenca lechera de Tizayuca, México).
Dr. Joel Hernández Cerón
Departamento de Reproducción
Noviembre 2011
2
Manejo Reproductivo
Animal (2011), 5:11, pp 1705–1719
Bio-economic model to evaluate twinning rate
using sexed embryo transfer in dairy herds
N. Ghavi Hossein-Zadeh1†, A. Nejati-Javaremi2, S. R. Miraei-Ashtiani2, H.
Kohram2 and M. Honarvar3
1Department of Animal Science, Faculty of Agriculture, University of Guilan, PO Box:
41635-1314, Rasht, Iran; 2Department of Animal Science, University College of
Agriculture and Natural Resources, University of Tehran, PO Box: 31587-77871,
Karaj, Iran; 3Department of Animal Science, Faculty of Agriculture, Azad University
of Shahriar Shahr-e-Qods, Iran
A stochastic bio-economic model has been used to
determine the effects of new reproductive technologies over
a 15-year period. A strategy of using conventional artificial
insemination (AI) or embryo transfer (ET) using two sexcontrolled embryos at different conception rates (CRs) and
herd sizes resulted in a 24 state model. The genetic means
of AI population increased over the years, and the genetic
means of milk production for all of the embryo strategies
were greater than those of AI. In addition, the genetic means
of milk yield using different embryo-based scenarios in the
expanding herds were greater than those for the fixed herds.
The net profit of using sexed ET in the expanding herds was
greater (P< 0.05) than that of fixed size herds. In general,
there was a roughly consistent trend in net profit per cow for
sexed ET strategies in the expanding herds over the years,
but there was an increasing trend in net profit per cow for
sexed ET strategies in the fixed herds over the years.
Medium to high CRs for ET and the use of sex-controlled
embryo systems, especially for induction of twin births to
produce dairy replacements, will be critical elements of a
system that produces significant numbers of female calves.
The greater number of female calves produced in the sexcontrolled scenarios allows the farmer to select animals with
the best genetic potential as dairy replacement heifers;
therefore, the rate of genetic gain increased in the dairy herd.
Results of sensitivity analyses showed that a significant
decrease in the production costs and increase in the ET
performance are essential for embryo-based technologies to
be profitable.
†E-mail: [email protected] or [email protected]
*****
Animal Reproduction Science 128 (2011) 100– 106
Effect of eCG on early resumption of ovarian
activity in postpartum dairy cows
B. Rostamia,b, A. Niasari-Naslajia,*, M. Vojgania, D. Nikjoua, H. Amanloub, A.
Geramic
a Department of Clinical Sciences, Faculty of Veterinary Medicine, University of
Tehran, Tehran, Iran
b Department of Animal Sciences, Faculty of Agriculture, Zanjan University, Zanjan,
Iran
c School of Mathematics, Statistics and Computer Science, University of Tehran,
Tehran, Iran
The purpose of the present study was to hasten the
resumption of ovarian activity early postpartum in lactating
dairy cows, using equine chorionic gonadotropin (eCG), to
enhance follicular growth, followed by hCG, to induce
ovulation. Primiparous Holstein dairy cows (n=21) were
assigned equally into eCG, eCG-hCG and Control groups.
Cows in the eCG and eCG-hCG groups received an i.m.
injection of eCG (500 IU Folligon(®)) on Day 6 postpartum.
Cows in the eCG-hCG group were also given an i.m. injection
of hCG (500 IU Chorulon(®)), once dominant follicle reached
the diameter of 13-16mm following eCG injection. Cows in
Control group did not receive any treatment. Daily blood
sampling and ultrasound examination were conducted,
starting at Day 6 postpartum until confirming the third
ovulation. Follicles ≥10mm in diameter were detected on Day
11.5±1.48, 10.1±0.52 and 11.1±1.36 after calving in Control,
eCG and eCG-hCG groups, respectively (P>0.05). The first
wave dominant follicle ovulated in 71.4% of cows treated with
eCG and eCG-hCG. In contrast, none of the first wave
dominant follicles ovulated in Control cows. By Day 20
postpartum, all cows in eCG group, 6/7 cows in eCG-hCG
group and none of the cows in Control group ovulated
(P<0.05). Short estrous cycles (≤16 days) were detected in
2/7, 1/7 and 6/7 cows in eCG, eCG-hCG and control groups,
respectively (P<0.05). In conclusion, injection of eCG on Day
6 postpartum could assist the early resumption of ovarian
activity by enhancing ovarian follicle growth and early
ovulation in postpartum cows. In this context, subsequent
hCG injection may not provide any more beneficial effect.
* Corresponding author at: E-mail address: [email protected] (A. Niasari-Naslaji).
*****
Noviembre 2011
3
Livestock Science 141 (2011) 123–128
High NEFA concentrations around parturition
are associated with delayed ovulations in
grazing dairy cows
Mauricio Javier Giuliodori a, Carole Delavaud b, Yves Chilliard b, Damasia
Becú-Villalobos c, Isabel Lacau-Mengido c, Rodolfo Luzbel de la Sota d,*
a Cátedra de Fisiología, Facultad de Ciencias Veterinarias, Universidad Nacional de
La Plata, Argentina
b INRA, UR1213 Herbivores, F-63122 Saint Genès Champanelle, France
c Instituto de Biología y Medicina Experimental, Conicet, Ciudad Autónoma de
Buenos Aires, Argentina
d Cátedra y Servicio de Reproducción Animal, Facultad de Ciencias Veterinarias,
Universidad Nacional de La Plata, Argentina
The objectives of this study were to assess indicators of
metabolic status of grazing dairy cows around parturition, and
the relationship between these indicators with the resumption
of ovulations postpartum (ROP). Holstein multiparous cows
(N=20) grazing on improved pastures and supplemented with
concentrates were body condition scored and tail bled weekly
from wk −2 through +9 related to parturition. Plasma samples
were analyzed for non-esterified fatty acids (NEFA), leptin,
insulin-like growth factor-1 (IGF-1) and progesterone (P4).
Data were analyzed with mixed models, logistic regression,
with receiver operator characteristic (ROC), and Cox
regression analysis. Cows having Delayed Ovulation ([DO],
ROP on week ≥5) had lower BCS, and higher NEFAs than
cows having a normal ROP around parturition (BCS:
2.73±0.08 vs. 2.94±0.05, P<0.05, and NEFA: 0.43±0.04 vs.
0.35±0.02mM, P<0.10, respectively). Also, DO cows had
lower BCS than normal herdmates (2.59±0.10 vs. 2.99±0.06,
P<0.01) around time of ROP, but they had similar NEFA,
leptin and IGF-1. The risk for DO increased as NEFA
increased (0.4% and 0.5% per every increasing mM of NEFA
in prepartum and postpartum, respectively). The ROC curve
showed that NEFA (prepartum and postpartum) had areas of
0.85 and 0.80, and cut-off values of 0.39 and 0.47mM.
Finally, hazard for ROP increased as prepartum IGF-1
increased, and it decreased as postpartum NEFA increased.
In conclusion, cows with lower BCS and higher prepartum
and postpartum NEFA had higher odds for getting DO than
herdmates with greater BCS and lower NEFA concentrations.
* Corresponding author at: E-mail address: [email protected] (R.L. de la Sota).
*****
J. Anim. Sci. 2011. 89:3551–3560
Long-term alteration of follicular steroid
concentrations in relation to subclinical
endometritis in postpartum dairy cows1
M. P. Green,*2 A. M. Ledgard,* S. E. Beaumont,* M. C. Berg,* K. P. McNatty,† A.
J. Peterson,* and P. J. Back‡
*Animal Biosciences Section, AgResearch Ltd., Ruakura Research Centre, Hamilton
3240, New Zealand; †School of Biological Sciences, Victoria University of
Wellington, Wellington 6140, New Zealand; and ‡Institute of Veterinary, Animal and
Biomedical Sciences (IVABS), Massey University, Palmerston North 11222, New
Zealand
The focus of this study was to investigate the effect of
subclinical endometritis (scEndo) on ovarian follicular steroid
concentrations in early postpartum pasture-fed dairy cows.
Mixed-age lactating dairy cows (n = 169) were examined to
ascertain uterine health status on d 21 postpartum (±3 d).
From this herd, a cohort of scEndo and uninfected cows (n =
47) were selected using uterine cytology to determine
scEndo. To ensure cows with scEndo were selected for the
study, a conservative threshold [>18% polymorphonuclear
(PMN) cells among uterine nucleated cells] was chosen as a
selection threshold. Ovarian follicular dynamics were
assessed by ultrasonography on d 21, 42, and 63
postpartum. On the latter 2 d, all follicles >4 mm in diameter
were ablated, and 4 d later, the largest (F1) and second
largest (F2) follicles were measured and their follicular fluid
aspirated. Hematological variables and plasma metabolites
were measured also on these days to further characterize
scEndo cows. On d 21, the prevalence of scEndo was
approximately 9% in this herd; by d 42 infections had selfresolved in the majority (81%) of those cows classified as
having scEndo on d 21. The scEndo cows had a delayed
return to cyclicity; however, no effect was evident on ovarian
follicle size or growth rate. Weeks after scEndo had selfresolved and cyclicity was restored, decreased (P = 0.07)
testosterone and increased (P = 0.07) cortisol concentrations
were evident in F1 follicles of scEndo compared with
uninfected cows. Progesterone concentrations of F1
increased (P < 0.05) in 11- to 16-mm diameter follicles of
scEndo cows, whereas estradiol, androstendione, and
dehydroepiandrosterone concentrations were decreased (P <
0.05) in F1 8- to 10-mm diameter follicles of scEndo cows.
These 3 steroids also differed (P < 0.05) between F1 follicle
size categories of scEndo but not uninfected cows. On d 21,
mean plasma albumin concentration was decreased (P =
0.02) in scEndo cows. In summary, early postpartum scEndo
had surprisingly long-term influences on the steroid
concentrations of ovarian follicles long after infections had
self-resolved. This is likely to affect oocyte quality and may
partially explain the reduced conception rates and longer
interval between calving and conception that are often
Noviembre 2011
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associated with scEndo, although more detailed
investigations are required to substantiate this theory.
2
Corresponding author: [email protected]
*****
Reprod Dom Anim 46, 781–786 (2011)
Effects of Induction of Ovulation with GnRH or
hCG on Follicular and Luteal Blood Flow in
Holstein–Friesian Heifers
S Aslan1, D Arslanbas2, N Beindorff2 and H Bollwein2
1Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Ankara
University, Ankara, Turkey; 2Clinic for Cattle, University of Veterinary Medicine,
Hannover, Germany
The objective of this study was to compare the effects of
gonadotropin-releasing hormone (GnRH) and human
chorionic gonadotropin (hCG) on follicular blood flow (FBF)
during the pre-ovulatory period and on luteal blood flow (LBF)
during dioestrus in Holstein–Friesian heifers. Twelve animals
were randomly divided into two groups and treated with either
intramuscular injection of 100 µg GnRH or intravenous (IV)
injection of 5000 IU hCG on Day 0 (oestrus, 48 h after
administration of PGF2α) to induce ovulation. Follicular size
(FS), FBF and time of ovulation were recorded with colour
Doppler sonography at 0, 1, 3, 6, 12 and 24 h after GnRH
and hCG treatment. Luteal size (LS) and LBF were
investigated on Day 9 and 12 after ovulation. Plasma
samples were taken to determine total oestrogens (Etot) and
progesterone (P4) after each examination. Ovulation occurred
between 24 and 48 h after treatment in all animals. No
difference (p > 0.05) was observed in FS between the two
treatment groups. Follicular blood flow was higher in the hCG
group than that was in GnRH group at 1 h after treatment (p
< 0.01). Total oestrogens were also higher (p < 0.01) in the
hCG group than GnRH group; however, this difference was
only obvious at 12 h after treatment. No difference (p > 0.05)
was observed in LS, LBF or P4 levels on Day 9 and 12
between treatment groups. In conclusion, the results suggest
that induction of ovulation with hCG and GnRH has a
temporary effect on FBF and oestrogen levels while no effect
on the size of corpora lutea, LBF and P4 levels was
observed.
Author’s address: SelimAslan, E-mail: [email protected]
Performance of dairy heifers in a silvopastoral
system
Domingos Sávio Campos Paciullo a, Carlos Renato Tavares de Castro a, Carlos
Augusto de Miranda Gomide a, Rogério Martins Maurício b,*, Maria de Fátima
Ávila Pires a, Marcelo Dias Müller a, Deise Ferreira Xavier a
a Embrapa Dairy Catlle, Rua Eugênio do Nascimento, 610, CEP 36038-330, Juiz de
Fora, MG, Brazil
b Federal University of São João Del Rey, Praça Frei Orlando, no 170, CEP 36307352 São João Del Rei, Minas Gerais, Brazil
The characteristics of the pasture and performance of dairy
heifers were evaluated in a silvopastoral system (SPS)
established with Brachiaria decumbens grass in a consortium
with four tree species (105trees/ha) and in a monoculture
system of Brachiaria decumbens (MS). Thirty-two paddocks
(0.5ha/paddock) were used, sixteen for each system (SPS
and MS). The paddocks were managed under rotational
stocking, with seven days occupation and 35 and 45days of
rest during the rainy and dry seasons, respectively. The
treatments were distributed in a randomised block design
with two repetitions. The heifers used had an initial weight of
200kg and a variable stocking rate as a function of the
herbage allowance of 7.0kg of DM/100kg of body weight/day.
The forage mass was estimated at each grazing cycle. For
each sample, the DM, crude protein and neutral detergent
fibre contents were determined as well as the in vitro dry
matter digestibility (IVDMD). All animals were weighed every
35days to estimate daily body weight gain and weight
production per area. The forage dry mass, stocking rate and
herbage allowance were similar between the systems
studied, but they varied according to season. Average values
of 2031 and 1100kg/ha/grazing cycle, 1.6 and 0.8AU (Animal
unit=450kg of body weight)/ha and 7.2 and 5.0kg DM/100kg
of body weight were estimated for the rainy and dry seasons,
respectively. The values for crude protein content were
higher in the SPS in the rainy season, while the NDF and
IVDMD did not vary with raising system. The body weight
gains per animal and per hectare in the dry season did not
vary, but were higher in the SPS during the rainy season in
the first and third experimental years. The annual body
weight gains were also higher in SPS than in the MS. It was
concluded that the SPS is more efficient for rearing dairy
heifers than the MS due to the higher body weight gain per
heifer and per area.
*Corresponding: E-mail address: [email protected] (R.M. Maurício).
*****
*****
Noviembre 2011
5
J. Dairy Sci. 94 :5487–5493
Reuse of norgestomet implants in an eCGbased superovulation protocol administered to
Nelore (Bos taurus indicus) cows
The effect of lameness on the fertility of dairy
cattle in a seasonally breeding pasture-based
system
Mateus José Sudano a,*, Fernanda da Cruz Landim-Alvarenga a,*, Roberto
Sartori b, Rui Machado c
a Department of Animal Reproduction and Veterinary Radiology, School of
Veterinary Medicine and Animal Science (FMVZ), São Paulo State University
(UNESP), 18618-970, Botucatu-SP, Brazil
b Department of Animal Science, University of São Paulo (USP), 13418-900,
Piracicaba, SP, Brazil
c Embrapa Southeast Cattle, PO Box 339, 13560-970, São Carlos-SP, Brazil
J. I. Alawneh, R. A. Laven,1 and M. A. Stevenson
Institute of Veterinary, Animal and Biomedical Sciences, Massey University,
Palmerston North, NZ 4471
This study assessed the reuse of norgestomet implants in
Nelore cows that were superstimulated with eCG. In a
crossover design trial, eight cows were randomly divided into
two experimental groups and twice superstimulated: Group 1
- half of the cows received a new norgestomet implant and
2mg estradiol benzoate (EB) on Day 0; Group 2 - remaining
cows received two once-used norgestomet implants and 2mg
EB also on Day 0. On Day 4 all cows received a single dose
of 2000IU eCG, and on Day 6 cows were treated with two
doses of PGF2α 12h apart. Ovulation was induced with
12.5mg pLH 12h after implant withdrawal (on Day 7), and
fixed-time artificial inseminations were carried out 12 and 24h
later. Seven days after pLH injection embryos were
recovered and blood samples were taken to determine
circulating progesterone. Ultrasound examinations were
performed at pLH administration and at embryo recovery.
The number of large follicles (≥8mm) was greater (P<0.05) in
Group 1 (17.1±1.8) than in Group 2 cows (9.7±1.6). The
mean number of corpora lutea was greater (P<0.05) for
Group 1 (13.8±1.8) as compared to Group 2 cows (5.4±1.0)
and the percentage of large follicles that ovulated following
pLH administration also differed (P<0.05) between
treatments (80.3% and 53.8% for cows in Groups 1 and 2,
respectively). However, no differences (P>0.05) were found
between treatments (respectively, for Group 1 and Group 2
cows) in the follicle diameter (10.5±1.6 and 10.2±1.7mm),
corpus luteum (CL) diameter (15.7±1.8 and 14.4±1.7mm),
CL volume (2232±1356 and 1893±1828mm3), ova/embryos
recovered (6.3±1.1 and 4.0±1.9), transferable embryos
(4.0±1.8 and 2.5±1.0) and plasma progesterone
concentration (36.1±8.3 and 35.1±6.9ng/mL). In conclusion,
the stimulatory effects on the ovaries provided by the use of
two once-used implants were less intense than the ones
verified after using a new implant.
* Corresponding authors at:
E-mail addresses: [email protected] (M.J. Sudano),
[email protected] (F.C. Landim-Alvarenga).
*****
The effect of lameness on the fertility of dairy cattle is well
recognized. But, the effect of lameness on the fertility of
seasonally breeding cattle in pasture-based systems is less
well characterized. This prospective cohort study of 463 cows
on 1 farm in the lower North Island of New Zealand was
designed to assess the effect of clinical lameness, as
identified by farm staff, on the hazard of conception after the
planned start-ofmating date. A Cox proportional hazards
model with time-varying covariates was used. After
controlling for the effect of parity, breed, body weight at
calving, and calving-to-planned start of mating interval, the
daily hazard of conception for cows identified as lame was
0.78 (95% confidence interval: 0.68–0.86) compared with
non-lame cows. Lame cows took 12 d longer to get pregnant
compared with their non-lame counterparts.
1 Corresponding author: [email protected]
*****
J. Anim. Sci. 2011. 89:3831–3837
Tail docking dairy cattle: Responses from an
online engagement1
D. M. Weary,2 C. A. Schuppli, and M. A. G. von Keyserlingk
Animal Welfare Program, Faculty of Land and Food Systems, University of British
Columbia, 2357 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
Tail docking remains a common practice on dairy farms in the
United States. This paper describes the results of an online
engagement designed to create discussion on tail docking, to
document the reasons participants put forward for and
against the practice, and to compare these reasons with the
literature available on this topic. A total of 178 people
responded; 30% were producers, 23% were veterinarians,
25% had no experience with the dairy industry, and 22%
included a mixture of teachers, students, and industry
professionals. Approximately 79% of participants were
opposed to docking. Responses varied with participant
demographics (e.g., females were more likely than males to
oppose docking), but in every demographic subgroup (e.g.,
by sex, age, country of origin, and dairy production
experience), the majority of respondents were opposed to tail
Noviembre 2011
6
docking. Common reasons for opposition to docking included
the lack of scientific evidence that docking improves
cleanliness or udder health, that docking is painful for cows,
that docking is unnatural, and that tails are important for
controlling flies. Some respondents in favor of docking cited
cow cleanliness as an issue, despite the scientific evidence
showing no positive effect of docking on cow cleanliness or
udder health. Additional reasons included protecting producer
safety. These results illustrate the range of reasons that are
cited for supporting and opposing tail docking. This approach
can be used to better target outreach efforts (e.g., improving
farmer education on the lack of positive effects of docking on
cleanliness and udder health while addressing concerns
about producer safety). More generally, this type of online
discussion provides a safe and productive format for
discussions about contentious issues in the dairy industry
and provides a mechanism for producers, industry
professionals, and the public to share perspectives on these
topics.
2 Corresponding author: [email protected]
*****
J Reprod. Dev. 57: 643-649 (2011)
Days in Milk at First AI in Dairy Cows; Its Effect
on Subsequent Reproductive Performance and
Some Factors Influencing It
Muhammad YUSUF1)2), Toshihiko NAKAO1), Chikako YOSHIDA1)3), Su Thanh
LONG1), Gokarna GAUTAM1), RMS Bimalka Kumari RANASINGHE1), Kana
KOIKE1) and Aki HAYASHI1)
1) Department of Veterinary Medicine, Faculty of Agriculture, Yamaguchi University,
Yamaguchi 753-8515, Japan
2) Department of Animal Production, Faculty of Animal Science, Hasanuddin
University, Makassar 90245, Indonesia
3) Field Center for Sustainable Agriculture and Forestry, Faculty of Agriculture,
Niigata University, Niigata 950-2181, Japan
The aim of the present study was to show the distribution of
cows by days in milk (DIM) at first AI, effect of DIM at first AI
on reproductive performance and some factors influencing
DIM at first AI. A total of 767 Holstein Frisian cows that
calved from January 2004 to December 2007 in 14 dairy
herds were used. The first AI conception rate (FAICR) was
34.0%. Seventy-five percent of the cows were first
inseminated within 100 days after calving. FAICR increased
linearly up to 100 DIM. A one unit (20 days) longer DIM at
first AI within the first 100 days postpartum increased the
likelihood of a 2.4% FAICR. However, cows first inseminated
at an earlier stage of lactation showed better reproductive
performance in terms of pregnancy rate and calving to
conception interval than cows first inseminated at a later
stage. A one day increase in the interval from calving to first
AI reduced the likelihood of 0.85 days to become pregnant.
Herd or region located in southwestern Japan, tie-stall herd,
first AI in spring, higher parity, uterine infection, metabolic
diseases and/or mastitis and abnormal resumption of
postpartum ovarian cycles contributed to delaying first AI.
Correspondence: T Nakao (e-mail:[email protected])
*****
J. Anim. Sci. 2011. 89:3531–3541
Influence of inducing luteal regression before a
modified controlled internal drug-releasing
device treatment on control of follicular
development1
J. K. Grant,* F. M. Abreu,† N. L. Hojer,* S. D. Fields,* B. L. Perry,* and G. A.
Perry*2
*Department of Animal and Range Sciences, South Dakota State University,
Brookings 57007; and †USDA-ARS Ft. Keogh Livestock and Range Research
Laboratory, Miles City, MT 59301
At the initiation of most controlled internal drug-releasing
(CIDR) device protocols, GnRH has been used to induce
ovulation and reset follicular waves; however, its ability to
initiate a new follicular wave is variable and dependent on
stage of the estrous cycle. The objectives of the current
studies were to determine 1) if inducing luteal regression
before the injection of GnRH at time of insertion of a CIDR
resulted in increased control of follicular development, and 2)
if removing endogenous progesterone by inducing luteal
regression before insertion of the CIDR decreased variation
in LH pulse frequency. In Exp. 1 and 2, Angus-cross cycling
beef heifers (n = 22 and 38, respectively) were allotted to 1 of
2 treatments: 1) heifers received an injection of PGF(2α) on d
-3, an injection of GnRH and insertion of a CIDR on d 0, and
a PGF(2α) injection and CIDR removal on d 6 (PG-CIDR) or
2) an injection of GnRH and insertion of a CIDR on d 0 and
on d 7 an injection of PGF(2α) and removal of CIDR (Select
Synch + CIDR). In Exp. 3, Angus-cross beef heifers (n = 15)
were assigned to 1 of 3 treatments: 1) PG-CIDR; 2) PGF(2α)
on d -3, GnRH on d 0, and PGF(2α) on d 6 (PG-No CIDR); or
3) Select Synch + CIDR. Follicular development and
ovulatory response were determined by transrectal
ultrasonography. Across all experiments, more (P = 0.02)
heifers treated with PG before GnRH initiated a new follicular
wave after the injection of GnRH compared with Select
Synch + CIDR-treated heifers. In Exp. 1, after CIDR removal,
interval to estrus did not differ (P = 0.18) between treatments;
Noviembre 2011
7
however, the variance for the interval to estrus was reduced
(P < 0.01) in PG-CIDR heifers compared with Select Synch +
CIDR heifers. In Exp. 3, there was a tendency (P = 0.09) for
LH pulse frequency to be greater among PG-CIDR and PGNo CIDR compared with the Select Synch + CIDR, but area
under the curve, mean LH concentrations, and mean
amplitude did not differ (P > 0.76). In summary, induction of
luteal regression before an injection of GnRH increased the
percentage of heifers initiating a new follicular wave.
Removal of endogenous progesterone tended to increase LH
pulse frequency, and the modified treatment increased the
synchrony of estrus after CIDR removal.
2 Corresponding
author: [email protected]
*****
J Reprod. Dev. 57: 613-619 (2011)
Effect of Follicular Aspiration at the Onset of
Progesterone-based Timed Artificial
Insemination on the Follicular Dynamics and
Fertility of Early Postpartum Japanese Black
Cows
Toh-Ichi HIRATA1), Naoki KON1), Akane SUGIYAMA1), Mai SATO1) and Takeshi
OSAWA1)
1) Faculty of Agriculture, Iwate University, Iwate 020-8550, Japan
The effect of gonadotropin-releasing hormone analogue
(GnRH-A) or follicular aspiration at the onset of
progesterone-based timed artificial insemination (TAI) on
subsequent follicular growth and synchronization of ovulation
was examined in early postpartum Japanese Black cows. A
total of 40 (22 in Exp. 1 and 18 in Exp. 2) Japanese Black
cows at 20-30 days postpartum were fitted with a
progesterone releasing internal device (PRID) for 7 days,
injected with a prostaglandin F2α analogue upon removal of
the PRID and GnRH-A 48 h later, and inseminated 18 h after
GnRH-A injection. In Exp. 1, the animals were divided into
three groups (untreated control, GnRH-A injection or follicular
aspiration) of different treatments on the first day of PRID
insertion (day 0), and the synchronized ovulation rate in the
follicular aspiration group (100%; 8/8) tended to be higher
(P=0.077) than that in the control group (42.9%; 3/7). In Exp.
2, follicular growth in the GnRH (n=9) and follicular aspiration
(n=9) groups was monitored by ultrasonography. Four out of
the nine animals in the GnRH group had a corpus luteum on
either day 4 or day 7 (OV group), and the other five animals
had no induced ovulation (NOV group). The diameter of the
ovulatory follicle on day 9 in the OV group (1.44 ± 0.11 cm)
tended to be greater (P=0.078) than that in the NOV group
(1.13 ± 0.07 cm). Follicular aspiration at the onset of PRIDbased TAI of early postpartum Japanese Black cows,
regardless of the resumption of ovarian cyclicity, tended to
result in a higher rate of synchronization of ovulation than
that of the untreated controls.
Correspondence: T-I Hirata (e-mail: [email protected])
*****
Theriogenology 76 (2011) 1416–1423
Pregnancy rates after fixed-time artificial
insemination of Brahman heifers treated to
synchronize ovulation with low-dose intravaginal
progesterone releasing devices, with or without
eCG
S.A.A. Butlera,*, P.C. Atkinsonb, G.B. Boe-Hansena, B.M. Burnsc, K. Dawsond,
G.A. Boe, M.R. McGowana
a School of Veterinary Science, The University of Queensland, Gatton, Queensland,
Australia
b PC & CE Atkinson Veterinarians, Allora, Queensland, Australia
c Queensland Alliance for Agriculture for Food Innovation, The University of
Queensland, Rockhampton, Queensland, Australia
d Animal Science, Agri-Science Queensland, Dutton Park, Queensland, Australia
e Instituto de Reproducción Animal Córdoba (IRAC), Córdoba, Argentina
The objective was to determine whether eCG in an ovulation
synchronization protocol with an intravaginal progesterone
(P4)-releasing device (IPRD) containing a low dose of P4
improves pregnancy rate (PR) to fixed-time AI (FTAI) in Bos
indicus heifers. Day 0, 2 y old Brahman heifers were
allocated to either eCG+ (n = 159) or eCG- (n = 157)
treatment groups. All heifers were weighed, body condition
scored (BCS), and ultrasonographically examined to
measure uterine horn diameter and presence of a CL. On
Day 0, all heifers received a low-dose IPRD (0.78 g P4) and 1
mg of estradiol benzoate (EB) im. On Day 8, the IPRD was
removed, all heifers received 500 μg cloprostenol im, and
those in the eCG+ treatment group received 300 IU of eCG
im. On Day 9, all heifers received 1 mg EB im. All heifers
were FTAI 52 to 56 h after IPRD removal. Ten days after
FTAI, heifers were exposed to bulls. Heifers were diagnosed
as pregnant to FTAI, natural mating, or not detectably
pregnant (NDP) 65 d after FTAI. Treatment with eCG+ as
compared to eCG- did not affect PR to FTAI (28.9 vs 30.6%;
P = 0.590), natural mating (51.3 vs 47.7%; P = 0.595), or
overall (65.4 vs 63.7%; P = 0.872). Mean live weight gain
from Days 0 to 65 d post-FTAI was higher in heifers pregnant
to FTAI (72.29 ± 4.26 kg; P = 0.033) and overall (66.83 ±
3.65 kg; P = 0.021), compared to heifers that were NDP
Noviembre 2011
8
(60.03 ± 3.16 kg). Uterine diameter group, 9-11, 12-13, and
14-20 mm (26.2, 31.3, and 33.3%; P = 0.256), presence and
absence of CL (29.8 vs 29.4%; P = 0.975), AI technicians 1,
2, and 3 (32.6, 28.8, and 22.4%; P = 0.293) and sires A, B,
and C (23.9, 36.0 and 27.0%; P = 0.122) had no effect on PR
to FTAI, natural mating, or overall. In conclusion, treatment of
primarily cycling Brahman heifers with 300 IU eCG in
conjunction with a low P4-dose (0.78 g) IPRD and EB to
synchronize ovulation, did not improve PR after FTAI, natural
mating, or overall.
* Corresponding author. E-mail address: [email protected] (S.A.A. Butler).
*****
Noviembre 2011
9
Artículos de Revisión
Reprod Dom Anim 46, 933–942 (2011)
Advances in Recombinant Gonadotropin
Production for Use in Bovine Superovulation
MW Hesser, JC Morris and JR Gibbons
Clemson University, Clemson, SC, USA
Bovine ovarian hyperstimulation is a process that currently
relies on pituitary-derived follicle stimulating hormone (FSH)
to facilitate the maturation of multiple follicles to achieve
dominance and eventual ovulation. The prevalence of this
process, also called superovulation, has more than doubled
in the past 10 years, but the efficiency of recovered
transferable embryos has remained low at ~6 per collection.
The use of pituitary-derived products presents other
problems including contamination from other hormones,
inconsistencies within and among batches, and the possibility
of the spread of disease-transmitting agents. Recombinant
gonadotropins have been engineered to yield varieties of
FSH and luteinizing hormone from a myriad of heterologous
hosts with the resulting products demonstrating various levels
of biological activity. Research has also been devoted to
alternative delivery methods to reduce the frequency of
injections required in current superovulatory protocols.
Together, recombinant gonadotropins and alternative delivery
approaches potentially provide an economical alternative to
the use of pituitaryderived products.
Author’s address (for correspondence):
E-mails: [email protected], [email protected]
*****
Reproduction (2011) 142 633–646
Endocrine-disrupting chemicals in ovarian
function: effects on steroidogenesis, metabolism
and nuclear receptor signaling
Zelieann R Craig, Wei Wang and Jodi A Flaws
Department of Comparative Biosciences, University of Illinois, 2001 S. Lincoln
Avenue, Urbana, Illinois 61802, USA
Endocrine-disrupting chemicals (EDCs) are exogenous
agents with the ability to interfere with processes regulated
by endogenous hormones. One such process is female
reproductive function. The major reproductive organ in the
female is the ovary. Disruptions in ovarian processes by
EDCs can lead to adverse outcomes such as anovulation,
infertility, estrogen deficiency, and premature ovarian failure
among others. This review summarizes the effects of EDCs
on ovarian function by describing how they interfere with
hormone signaling via two mechanisms: altering the
availability of ovarian hormones, and altering binding and
activity of the hormone at the receptor level. Among the
chemicals
covered
are
pesticides
(e.g.
dichlorodiphenyltrichloroethane
and
methoxychlor),
plasticizers (e.g. bisphenol A and phthalates), dioxins,
polychlorinated biphenyls, and polycyclic aromatic
hydrocarbons (e.g. benzo[a]pyrene).
Correspondence should be addressed to J A Flaws; Email: [email protected]
*****
Biology of Reproduction 85, 871–883 (2011)
Xenobiotic Effects on Ovarian Preantral
Follicles1
Connie J. Mark-Kappeler,3 Patricia B. Hoyer,3 and Patrick J. Devine2,4
Department of Physiology,3 University of Arizona, Tucson, Arizona INRS-Institute
Armand-Frappier,4 Institut National de la Recherche Scientifique, Laval, Québec,
Canada
Women are born with a finite population of ovarian follicles
which are slowly depleted during their reproductive years
until reproductive failure (menopause) occurs. The rate of
loss of primordial follicles is determined by genetic and
environmental influences, but certain toxic exposures can
accelerate this process. Ionizing radiation reduces pre-antral
follicle numbers in rodents and humans in a dose-dependent
manner. Cigarette smoking is linked to menopause occurring
1-4 years earlier than with nonsmokers, and components of
smoke, polycyclic aromatic hydrocarbons, can cause follicle
depletion in rodents or in ovaries in vitro. Chemotherapeutic
agents, such as alkylating drugs and cisplatin, also cause
loss of pre-antral ovarian follicles. Effects depend on dose,
type and reactivity of the drug, and the age of the individual.
Evidence suggests DNA damage may underlie follicle loss
induced by one common alkylating drug, cyclophosphamide.
Occupational exposures have also been linked to ovarian
damage. 2-bromopropane caused infertility in men and
women in an industrial setting and can induce ovarian follicle
depletion in rats. Solvents, such as butadiene, 4vinylcyclohexene, and their diepoxides can also cause
specific pre-antral follicle depletion. The mechanism(s)
underlying effects of the latter compound may involve
alterations in apoptosis, survival factors such as KIT/Kit
Ligand, and/or the cellular signaling that maintains primordial
follicle dormancy. Estrogenic endocrine disruptors may alter
follicle formation/development and impair fertility or normal
Noviembre 2011
10
development of offspring. Thus, specific exposures are
known or suspected of detrimentally impacting pre-antral
ovarian follicles, leading to early ovarian failure.
2 Correspondence and current address: e-mail: [email protected]
*****
Terminologies for the pre-attachment bovine
embryo
Jaana Peippoa, Zoltan Machatyb, Augustine Peterc,*
a MTT Agrifood Research Finland, Biotechnology and Food Research, FI-31600
Jokioinen, Finland
b Department of Animal Sciences, Purdue University, West Lafayette, Indiana, USA
c Department of Veterinary Clinical Sciences, Purdue University, West Lafayette,
Indiana, USA
There are numerous publications regarding bovine embryos,
ranging from descriptions of their appearance and
development to emerging techniques in the field of assisted
reproductive technology (ART). Concurrently, several
specialized terms have been developed to describe the
bovine embryo. Many of these terms are simple, some are
difficult to understand and use, and others are antiquated
and may not be scientifically accurate. For example, use of
terms such as syngamy, conception rate, implantation and
embryo resorption should be revisited. This review presents a
brief overview of current knowledge regarding the preattachment period of the bovine embryo and attempts to
define the terms. In this process, conventional terminology is
presented, and contemporary and novel terms are proposed
from a biological perspective.
* Corresponding author. E-mail address: [email protected]
*****
Noviembre 2011
11
Fisiología Reproductiva
In vivo and in vitro studies of the role of the
adrenergic system and follicular wall contractility
in the pathogenesis and resolution of bovine
follicular cysts
A. Rizzo, M. Spedicato, M. Mutinati, G. Minoia, M. Pantaleo, R.L. Sciorsci*
Department of Animal Production, University of Bari Aldo Moro
Bovine follicular cysts (FCs) are a common cause of
economic loss in modern dairy herds. Their
aetiopathogenesis is not completely understood, even though
an inadequate hypothalamic release of GnRH at the time of
ovulation is considered to be their main cause. Much
evidence, however, suggests a role for adrenergic
innervation in ovarian functions, such as follicular
development, steroid hormone secretion, and follicular
contractility, the latter being an event important for ovulation.
Moreover, in humans, polycystic ovary syndrome, a disease
very similar to bovine follicular cysts, is characterised by
increased density of adrenergic nerves. Given these
premises, the aim of our study was to evaluate the
effectiveness and mode of action of a novel strategy for the
treatment of bovine follicular cysts. In the in vivo experiment,
170 Friesian cows diagnosed with follicular cysts were
assigned to four groups (groups A, B, C, and D) to assess
the effects of epidural administration of a β-adrenergic
antagonist (carazolol) alone or in combination with a GnRH
analogue (lecirelin). The four groups underwent the following
treatments: Group A was administered lecirelin in
combination with carazolol; Group B was administered
carazolol; Group C was administered lecirelin; and Group D
was administered only normal saline solution. In the in vitro
experiment, strips of the walls of cystic follicles recovered
post-mortem were suspended in an organ bath, connected to
an isometric force transducer and exposed to increasing
doses of epinephrine or to the same treatment after exposure
to carazolol for 15 min (n = 10). The amplitude and frequency
of the contractile activity were recorded. None of the control
cows was observed in oestrus or was submitted to AI. The
combination of lecirelin and carazolol induced a significant
increase in the number of cows in oestrus (88%) compared to
lecirelin alone or to carazolol alone (P < 0.05 and P < 0.01,
respectively). The combination of lecirelin and carazolol and
lecirelin alone were significantly more efficacious than
carazolol alone (P < 0.01 and P < 0.05, respectively). In the
in vitro experiment, epinephrine increased the amplitude of
the contractions of the strips in a dose-dependent manner.
This response was significantly enhanced in strips pretreated with carazolol. The treatments had no effect on the
frequency of contractions. In conclusion, our work
demonstrates that the epidural administration of a GnRH
analogue and a β-adrenergic blocker is an effective means of
treating cows with cystic ovarian disease. Moreover, it
confirms, from a clinical point of view, that alterations of the
adrenergic system and of the contractility of the follicular wall
can be considered aetiopathogenic factors involved in the
development of FCs. The results of this study lay the basis
for a new therapeutic approach to FCs.
*****
Reproduction, Fertility and Development
Inclusion of bovine lipoproteins and the vitamin
E analogue, Trolox, during in vitro culture of
bovine embryos changes both embryo and fetal
development
J. A. RookeA,C, R. G. WattA, C. J. AshworthA,B and T. G. McEvoyA
Livestock Systems Group, SAC, West Mains Road, Edinburgh EH9
3JG, UK.
BThe Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian
EH25 9RG, UK.
ASustainable
This experiment investigated effects of lipoproteins and
Trolox (vitamin E analogue) on bovine embryo and fetal
development. The treatments were: in vitro culture (IVC) in
synthetic oviducal fluid alone (SOF); with bovine lipoproteins
(2% v/v; SOFLP); with Trolox (100 µM; SOFT); and with
lipoproteins and Trolox (SOFLPT). In vitro culture with
lipoproteins increased fatty acid content of blastocysts (P<
0.001) whereas inclusion of Trolox had no effect (P>0.05).
Whereas lipoproteins reduced zygote development to
blastocysts (P=0.03), Trolox facilitated increased
development (P<0.001) and counteracted the reduction
observed with lipoproteins (interaction, P= 0.009).
Lipoproteins also compromised (P<0.001) but presence of
Trolox (P>0.05) had no effect on blastocyst morphological
grade. Pregnancy rates resulting from synchronous transfer
of IVP embryos were not affected by IVC treatment. At Day
70 of pregnancy, compared with SOF, fetal weight was lower
in SOFLP but not SOFLPT (interaction, P<0.001). Liver
Noviembre 2011
12
weight (g kg -1 fetal weight) was greater (P=0.03) in
treatments containing Trolox. Placentome numbers were
greater in SOF and SOFLPT compared with SOFLP and
SOFT (interaction, P=0.002); superior embryo grades were
also associated with increased numbers of placentomes
(P=0.024). In conclusion, the interactive effects of lipoprotein
and Trolox inclusion on in vitro embryo development were
also evident in fetal development at Day 70.
CCorresponding
author. Email: [email protected]
*****
Influence of insulin-like growth factor-binding
proteins-2 and -3 in the pathogenesis of cystic
ovarian disease in cattle
Fernanda M. Rodrígueza,b, Natalia R. Salvetti a,b, Carolina G. Panzania, Claudio
G. Barbeitob,c, Hugo H. Ortegaa,b, Florencia Reya,b,*
a Departamento de Ciencias Morfológicas, Facultad de Ciencias Veterinarias,
Universidad Nacional del Litoral, Esperanza, Santa Fe, Argentina
b Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos
Aires, Argentina
c Instituto de Patología & Cátedra de Histología y Embriología, Facultad de Ciencias
Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina
Ovarian cysts are one of the major causes of infertility in
dairy cows. The development is associated with an endocrine
imbalance in the hypothalamo-hypophyseal-gonadal axis in
which endocrine factors participate in follicular growth and
differentiation and in the secretion of ovarian hormones.
Insulin-like growth factor family are essential local regulators
of ovarian follicle development and functionality and actions
are mediated by binding protein activity. The aim of the
present study was to analyze the expression of IGFBP-2 and
IGFBP-3 in developing follicles of normal estrous cycling
animals and with spontaneous and induced cystic ovarian
disease (COD) to determine IGF bioavailability. The mRNA of
IGFBP-2 and IGFBP-3 in follicular walls was quantified by
reverse transcription-polymerase chain reaction (RT-PCR)
and in situ hybridization. Protein expression was analyzed by
immunohistochemistry. The results demonstrated reduced
amounts of mRNA of both IGFBPs in the granulosa cells of
ovarian follicles of animals with COD (P<0.05). The present
study suggests that the IGF system or imbalances between
IGFs and IGFBPs may be involved in COD of cattle.
* Corresponding author at: E-mail address: [email protected] (F. Rey).
Liposomes for cryopreservation of bovine sperm
T. Röpkea, H. Oldenhofb, C. Leidingc, H. Siemeb, H. Bollweina, W.F. Wolkersd,*
for Cattle, University of Veterinary Medicine Hannover, Hannover, Germany
b Clinic for Horses - Unit for Reproductive Medicine, University of Veterinary
Medicine Hannover, Hannover, Germany
c AI Center Neustadt/Aisch, Neustadt/Aisch, Germany
d Institute of Multiphase Processes, Leibniz Universität Hannover, Hannover,
Germany
a Clinic
In this study, the effect of various unilamellar liposomes on
cryopreservation of bovine spermatozoa has been
investigated. Liposomes were composed of saturated lipids
with various acyl chain lengths: DSPC (18:0), DPPC (16:0),
DMPC (14:0), or DLPC (12:0). Alternatively, liposomes were
prepared using unsaturated egg phosphatidylcholine (EPC)
or DOPC (18:1, neutral), alone or in combination with lipids
with various head groups: DOPS (negatively charged),
DOPG (negatively charged), and DOPE (neutral). Fourier
transform infrared spectroscopy studies showed that bovine
sperm membranes display a gradual phase transition from 10
to 24 ºC. Phase transition temperatures of the liposomes
varied from -20 to +53ºC. Sperm was incubated in the
presence of liposomes for either 6 or 24 h at 4 °C prior to
freezing. Postfreeze survival rates were determined based on
the percentage of progressively motile cells as well as the
percentage of acrosome- and plasma membrane-intact cells.
With DOPC liposomes a postthaw progressive motility of
43% was obtained compared with 59% using standard egg
yolk freezing extender. Postthaw progressive motility
increased up to 52% using DOPC:DOPG (9:1) liposomes,
whereas DOPC:DOPS or DOPC:DOPE liposomes did not
increase survival compared with DOPC liposomes. Among
the saturated lipids, only DMPC was found to increase
cryosurvival, up to 44% based on progressive motility. DLPC
liposomes caused a complete loss in cell viability, already
prior to freezing, whereas DPPC and DSPC liposomes
neither positively nor negatively affected cryosurvival. Taken
together, the higher postthaw survival obtained with
DOPC:DOPG liposomes as compared with DOPC liposomes
can likely be attributed to increased liposome-sperm
interactions between the charged phosphatidylglycerol
groups and charged regions in the sperm membranes.
Interestingly, the lipid phase state of the liposomes during
preincubation is not the decisive factor for their cryoprotective
action.
*****
*****
Noviembre 2011
13
Pulses of prolactin before, during, and after
luteolysis and synchrony with pulses of a
metabolite of prostaglandin F2α in heifers
O.J. Ginthera,b,*, M.A. Begb
a Eutheria Foundation, Cross Plains, WI 53528, USA
b Department of Pathobiological Sciences, University of Wisconsin-Madison, WI
53706, USA
Pulses of prolactin (PRL) and a metabolite of prostaglandin
F2α (PGFM) were determined from hourly blood samples
collected before, during, and after luteolysis (n=7 heifers).
Progesterone concentrations were used to partition the
results into six 12-h sets from 12h before to 36h after
luteolysis. Pulses of PRL with a nadir-to-nadir interval of
4.4±0.2h were detected in each 12-h set. Pulses were
rhythmic (P<0.05) in six heifers, beginning 12h before the
end of luteolysis. The peak of a PRL pulse was greater
(P<0.05) for the 12h after the end of luteolysis than for other
12-h sets, except for the last set of luteolysis. Area under the
curve of a pulse was greater (P<0.05) for the 24h that
encompassed the end of luteolysis than for two previous 12-h
sets. Synchrony between the peaks of PRL and PGFM
pulses was greater (P<0.03) during and after luteolysis
(same hour for 29/39 pairs) than before luteolysis (0/12).
Concentration of PRL centralized to the peak (Hour 0) of
PGFM pulses was greater (P<0.05) at Hours 0 and 1 than at
Hours -2, -1, and 3. Results supported the hypothesis that
PRL is secreted in pulses in heifers. The pulses were most
prominent and rhythmic during the last 12h of luteolysis and
thereafter. The pulse peaks of PRL and PGFM were
synchronized for most PRL pulses during and after luteolysis.
during luteolysis to the end of the second pulse. Mares (n=7)
were selected with a 9-h interval between the peaks of the
two pulses. In mares, estradiol-17β (estradiol) increased
(P<0.05) within each PGFM pulse and plateaued for a mean
of 6h between the pulses, resulting in a stepwise estradiol
increase. Progesterone decreased linearly (P<0.0001)
throughout the intra-pulse and inter-pulse intervals of PGFM.
In heifers (n=6), inter-pulse intervals were variable, and
therefore Hours 1-4 of the first pulse (Hour 0=PGFM peak)
and Hours -4 to -1 of the second pulse were used to
represent the mean 8-h interval between peaks of the two
pulses. Estradiol increased (P<0.05) during the ascending
portion of each PGFM pulse and then decreased (P<0.05)
beginning at Hour -1 of the first PGFM pulse and Hour 0 of
the second pulse. The 1-h delay during the second pulse was
accompanied by an apparent increase in PRL. A transient
decrease in estradiol occurred in individuals between PGFM
pulses at a mean of 5h after the first PGFM peak,
concomitant with a transient LH increase (P<0.05). Results
indicated that estradiol plateaued in mares and fluctuated in
heifers during the interval between PGFM pulses. Heifers
also showed temporal relationships between estradiol and LH
and apparently between estradiol and PRL.
* Corresponding author at: E-mail addresses: [email protected],
[email protected] (O.J. Ginther).
* Corresponding author at: E-mail address: [email protected] (O.J. Ginther).
*****
Concentrations of circulating hormones during
the interval between pulses of a PGF2α
metabolite in mares and heifers
O.J. Ginthera,b,*, M.B. Rodrigueza, M.A. Begb
a Eutheria Foundation, Cross Plains, WI 53528, USA
b Department of Pathobiological Sciences, School of Veterinary Medicine, University
of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA
The temporal relationship of several hormones to a
metabolite of prostaglandin F2α (PGFM) was studied in
mares and heifers from the beginning of the first PGFM pulse
Noviembre 2011
14
Sitios de Interés

Agrociencia
http://www.colpos.mx/agrocien/agrociencia.htm

Animal

Animal Reproduction
http://www.cbra.org.br/publicacoes/animalreproduction/issues.do

Animal Reproduction Science
http://www.sciencedirect.com/science/journal/03784320

Biology of Reproduction
http://www.biolreprod.org/

Ciencia

Domestic Animal Endocrinology

Journal of Animal Science
http://jas.fass.org/

Journal of Dairy Science
http://jds.fass.org

Journal of Dairy Research
http://journals.cambridge.org/action/displayJournal?jid=DAR

Journal of Reproduction and Development
http://www.jstage.jst.go.jp/browse/jrd

Livestock Science

Manejo lechero
http://www.manejolechero.com/

Nature
http://www.animal-journal.eu/
http://www.revistaciencia.amc.edu.mx/
http://www.nature.com/nature/index.html
Noviembre 2011
15

Physiological . Reviews
http://physrev.physiology.org/

Proceedings of the National Academy of Sciences of the United States of America
http://www.pnas.org/

Reproduction
http://www.reproduction-online.org/

Reproduction in Domestic Animals
http://www.wiley.com/bw/journal.asp?ref=0936-6768

Reproduction, Fertility and Development
http://www.publish.csiro.au/nid/44.htm

Revista Mexicana de Ciencias Pecuarias
http://www.tecnicapecuaria.org.mx/index2.php

Science
http://www.sciencemag.org/

The American Association of Bovine Practitioners
http://www.aabp.org/

The Dairy Cattle Reproduction Council (DCRC)
http://www.dcrcouncil.org/index.html

The Veterinary Record
http://veterinaryrecord.bvapublications.com/

Theriogenology
http://www.sciencedirect.com/science/journal/0093691X

Veterinary Clinics of North America: Food Animal Practice
http://www.vetfood.theclinics.com/

Veterinaria México
http://www.fmvz.unam.mx/fmvz/revvetmex/revvetmex.htm
Noviembre 2011
16
Noviembre 2011
17

Noviembre 2011 - FMVZ-UNAM

Transcription

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