Chapter 8: Considerations Concerning Stocking rate

Comments

Transcription

Chapter 8: Considerations Concerning Stocking rate
Chapter 8: Considerations Concerning
Stocking rate
1. The concept of grazing capacity.
2. What we have learned from stocking rate
studies.
3. Grazing intensity versus grazing timing.
4. Components of stocking rate.
a. Distance from water and slope
b. Forage demand by grazing animals
c. The harvest coefficient
d. Stocking rate calculation
5. Benefits of conservative stocking.
6. Stocking rate economics.
Cornerstones of Grazing Management
1.
2.
3.
4.
Proper stocking rate
Proper distribution
Proper kinds of animals
Proper grazing system
• ***Proper stocking rate is most important
Conservative versus Heavy stocking
90
90
80
80
70
70
60
60
50
East
West
North
40
30
50
40
30
20
20
10
10
0
1st 2nd 3rd 4th
Qtr Qtr Qtr Qtr
East
West
North
0
1st 2nd 3rd 4th
Qtr Qtr Qtr Qtr
Stocking vs. Specialized grazing
systems
Range research shows stocking rate has had a
much bigger impact on range vegetation and
financial returns than specialized grazing
systems.
Specialized grazing systems will not overcome
the impacts of excessive stocking.
Stocking rate vs season of use
• Stocking rate has had much more effect
on rangeland vegetation than season of
use
Table 20. Effects of grazing management on semi-desert
grass-shrub rangeland in southeastern Arizona.
__________________________________
Characteristics
Continuous
yearlong grazing
Summer
grazing
Winter
grazing
10
12.53
46.0
155.1
10
12.53
41.6
169.4
_________________________________________________________________________________________________________________________________________________________________
Duration of study
Annual precipitation (in)
% Grazing use
Forage production (lb/ac)
Perennial grass prod.
(lb/ ac)
Calf weight (lbs)
Range Trend
10
12.53
47.2
220.5
89.4
414
up
27.5
396
stable-down
42.4
396
stable-down
Table 20b. Perennial grass yields and cover
showed the greatest increases where percent
use was lowest. Both vegetation and cattle
performances was higher under year-long than
seasonal grazing. The authors recommended
that grazing use on the perennial grasses not
exceed 40%. Stocking these ranges for about
35% use of forage with some destocking in dry
years was considered the best strategy.
Source: Martin, S.C. 1975; Martin, S.C. and D.R. Cable, 1974.
Definitions of some grazing terms
Heavy grazing- a degree of herbage utilization
that does not permit desirable forage species to
maintain themselves.
Moderate grazing- a degree of herbage
utilization that allows palatable species to
maintain themselves.
Light grazing – a degree of herbage utilization
that allows palatable species to maximize their
herbage producing ability.
Definitions continued
Conservative grazing – a degree of herbage
utilization between light and moderate, generally
involving about 35% use of forage.
Severe grazing – a degree of herbage
utilization generally above 60% use of forage
that results in long term damage to the range.
Stocking Rate and Forage
Production
Heavy stocking has greatest effects
on forage production in drought
years.
Table 12. Forage Production (lbs/acre) on Heavily and Moderately Stocked
Pastures in Drought Compared to 10-years Average on the Fort Stanton Experimental
Range in New Mexico.
Drought
Years
Grazing intensity
1974
Heavy
(50-55% use)
Moderate
(40-45% use)
10 years
Average
(1970-1979)
Drought year
as percent
of average
103
607
17%
235
740
32%
Source: Pieper et al. 1991, Holechek, 1994.
Table 13. Forage Production (lbs/acre) on Moderately and Conservatively
Stocked Pastures in Drought Compared to 6-years average on the Chihuahuan Desert
Rangeland Research Center.
Grazing intensity
Drought
6 year
Drought year
years
Average
as percent
1994 & 1995 1993-1998 of Average
Moderate
(40-45% use)
44
194
23%
Conservative
(30-35% use)
89
273
33%
Source Molinar 1999, Molinar et al, 2002.
Table 6. Influences of grazing intensity on cattle
production (yearlings) on ponderosa pine
bunchgrass in Colorado1
____________________________________________________
Heavy
Moderate
Light
_______________________________________
Study duration years
Length of grazing months
Period of grazing
Acres/ yearling
% use of forage
Forage prod (lb/ ac)
Gain/ head (lbs)
Net return ($ ac)
6
5
Jun-Oct
12
58
1,256
172
0.74
Source Johnson W.M. 1953, USDA. Circ. 929
6
5
Jun-Oct
13
33
1,565
211
1.35
6
5
Jun-Oct
24
16
2,037
231
0.98
Stocking vs. Specialized grazing
systems
Range research shows stocking rate has had a
much bigger impact on range vegetation and
financial returns than specialized grazing
systems.
Specialized grazing systems will not overcome
the impacts of excessive stocking.
Grazing capacity and stocking rate
Grazing capacity - maximum animal numbers
which can graze each year on a given area of
range, for a specific number of days without
inducing a downward trend in range condition.
‰ It is based on vegetation weight, not cover.
Stocking rate – the actual number of animals
assigned to a rangeland unit for a given time
period.
Components of weight estimate-key area
grazing capacity (Holechek 1988)
1. Land area
determination
2. Adjustment for
ungrazable range
3. Determination of forage
production
4. Selection of utilization
Coefficient
5. Determination of forage
demand by livestock
and game animals
6. Adjustment for distance
form water
7. Adjustment for slope
8. Computation of grazing
capacity
9. Interpretation of grazing
capacity relative to
recent precipitation
10. Use of stubble heights
to cross-check actual
use.
Stocking ranges
How many days? How many animals?
500 lbs forage per acre (dry)
200 acres
100,000 lbs total
100,000 lbs X 0.35 (harvest coefficient)=35,000 lbs
grazable forage
325 lbs forage per acre needed to protect the site
200 acres
65, 000 lbs forage that must be left on the site for
protection
100,000 – 65000= 35, 000 lbs (can be consumed)
Stocking ranges cont.
You have the following animals
10 cows (average weight = 800 lbs) = 8000 lbs
1 bull ( average weight = 1100 lbs) = 1,100 lbs
9 calves ( average weight = 200 lbs) = 1,800 lbs
10, 900 lbs
Stocking ranges cont.
• Ruminant animal will eat 2% of body
weight/day
• (ranges from 2.6 on high quality forage to 1.4
on mature forage)
10, 900 x .02 = 218 lbs. forage consumed/day
35,000/218 = 160 days of grazing, however this
is only a guideline.
Uses of grazing capacity information
1. Forage allocation to livestock and wildlife.
2. Quantification of forage resources on a
pasture, ranch, or allotment.
3. Assignment of stocking rate when data are
lacking on trend and grazing intensity.
4. Assignment of stocking rate when data are
lacking or uncertain on past stocking rates.
Uses of grazing capacity information
cont.
5. Determines ranch monetary value.
* Grazing capacity is the most expensive of the
4 types of grazing surveys (trend, intensity,
capacity, condition).
** Sound grazing capacity data requires at least
3 years of data collection.
Problems with stocking at grazing
capacity
1. Major reductions in livestock numbers will
be needed in one half the years to avoid
rangeland degradation.
2. Difficulty in accurately estimating forage
crops.
3. Stocking at capacity generally does not
permit rangeland improvement.
4. Stocking at capacity gives lower financial
returns than conservative stocking ( 80-90%
of capacity)
Problems with stocking at grazing
capacity cont.
5. Severe financial losses can occur under
drought conditions.
6. Multiple use values are difficult to maintain.
* Stocking at capacity involves about 40% use
forage on New Mexico rangelands.
** Considerable research shows the financially
most effective stocking rate is well below
what the rangeland vegetation will sustain.
Table 6. Influences of grazing intensity on cattle
production (yearlings) on ponderosa pine
bunchgrass in Colorado1
____________________________________________________
Heavy
Moderate
Light
_______________________________________
Study duration years
Length of grazing months
Period of grazing
Acres/ yearling
% use of forage
Forage prod (lb/ ac)
Gain/ head (lbs)
Net return ($ ac)
6
5
Jun-Oct
12
58
1,256
172
0.74
Source Johnson W.M. 1953, USDA. Circ. 929
6
5
Jun-Oct
13
33
1,565
211
1.35
6
5
Jun-Oct
24
16
2,037
231
0.98
Table 8. Yearling cattle production and financial return characteristics at
the Central Great Plains Experimental Range, Colorado
Grazing Intensity
Excessive
Moderate
Forage production (lbs/acre)
Forage utilization (%)
Weight again per animal (lbs)
Weight again per unit area (lbs/acre)
Death loss (%)
Gross income/acre ($)
Gross income/yearling ($)
536
54
218
22
1.43
1.54
81.22
689
37
268
34
0.33
1.93
96.02
Source; Kipple, G.E., and D.F. Costello. (1960). Vegetation and cattle to different
intensities of grazing on shortgrass range of the central Great Plains. U.S. Dept.
Agric. Tech. Bull. 1216.
Stocking plans recommended for New
Mexico and other western rangelands.
1. Stock for about 30%
use of long term
average forage
production.
2. Apply flexible stocking
in drought.
3. In dry years sell older
cows
4. Always sell livestock to
level forage resources
will support;
avoid expensive feeding
programs.
5. Rest or lightly graze for
2 growing seasons after
severe drought.
6. Restock with about one
half normal herd first
year after severe
drought.
Benefits of conservative grazing (30-35%
use of forage)
1. Maximized long term (and often short term)
financial returns from ranching
2. Permits improvement in forage productivity.
3. Reduces risk of damage to range from heavy
grazing in drought.
4. Facilitates multiple use concept on public
lands.
5. Strongly and broadly recommended by
researchers conducting long term razing
studies.
Guidelines to proper use
Heavy use- Range has a “clipped” or mowed
appearance. Over half of the fair and poor
forage-value plants are used. All accessible
parts of the range show use, and key areas
are closely cropped. They may appear
stripped if grazing is severe. There is
evidence of livestock trailing to forage.
Moderate use (proper use)- About one-half of
the good and fair forage value plants are
used. There is little evidence of livestock
trailing. Most of the accessible range shows
some use.
Guidelines to proper use cont.
Light use- Only choice plants and areas are
used. There is no use of poor forage
plants. The range appears practically
undisturbed.
‰ On key areas average stubble heights of
12 to 14 inches for tall grasses, 6 to 8
inches for mid grasses and 2 to 3 inches
for short grasses are recommended
minimums for proper use.
Guidelines on management changes
• If grazing intensity is heavy on 30% or more
of a pasture two years in a row or in 2 years
out of 5 management changes are need
• If grazing intensity becomes severe on one
third or more of the pasture in any year,
management changes should be implemented

Similar documents