2002 Unified Beef Cattle and Range Research Report (continued)
Southwest Feeders Project: 2002 Calf Backgrounding
Test
Leif Anderson1, Dan
Nudell1, Chip Poland2, Tim
Faller1, and Don Stecher1
The Southwest Feeders Project at the Hettinger Research Extension Center
is providing education and research programs for producers interested in
backgrounding calves in southwest North Dakota. In addition to determining
added returns to the livestock operation, the added value to forage crops
through livestock feeding is being evaluated for the income potential in
diversified operations. The coming year will provide the opportunity to
expose these findings to many more producers through additional education
and demonstration programs.
Producers in southwest North Dakota are continually looking for
opportunities to increase income and sustainability of their farm and
ranch enterprises. The Southwest Feeders Project was developed to
address these issues by creating a program that combined both the
educational and research components into a hands-on, producer-driven
initiative. The first year's goal was to provide producers with the resources
to evaluate the performance and economics of their steer calves in
a custom backgrounding environment, while minimizing individual risk
by feeding a smaller number of cattle. Cooperating producers
participated by consigning multiples of eight head of calves which averaged 583
pounds. After a 56-day feeding trial, calves averaged 2.76 lbs/day for an
off-test weight of 737 lbs. Feed cost per pound of gain was $0.28 with a
total cost of gain of $0.42. Based on an independent valuation of calves
on- and off-test of $83.50 and $82.98, respectively, net return per head
was $54.30. In addition, there was a $33 net return per acre for the
raised barley-pea haylage. With a goal of adding value through locally
available livestock and feed, this backgrounding test provided cooperating producers
a base with which to measure livestock and crop production opportunities.
Introduction
Southwest Feeders is a multi-faceted project designed to enhance
value-added economic development in southwestern North Dakota
through education and research programs involving production systems
that utilize locally produced feedstuffs, calves and lambs. A new calf
background feeding facility (24 pens, 192 head capacity) has been constructed
at the Hettinger Research Extension Center to directly support the
educational and research components of this project. This facility will also
be used in the summer to augment current lamb finishing research at
the center. Lamb finishing work will begin in the research lot during
the spring of 2003.
In addition to cattle backgrounding and lamb finishing at the
Hettinger Research Extension Center, producers will have additional
educational opportunities and resources available. Throughout the year,
Southwest Feeders will host a Feeder's Field Day for producers and offer
additional county meetings and one-on-one farm/ranch visits.
There is in excess of $20,000,000 in economic activity available to
the agricultural community of southwestern North Dakota associated
with beef backgrounding. Statewide the potential level of economic
activity exceeds $55,000,000. Lamb finishing would increase on the statewide
level by $2,100,000. Southwest Feeders is designed to actively engage
the agricultural community of southwestern North Dakota in
value-added livestock production through a coordinated and targeted research
and education program in calf backgrounding and lamb finishing.
The 2002 calf backgrounding test was structured as a research and
education demonstration project allowing producers to evaluate cattle
performance in a controlled backgrounding environment.
Procedure
The test began Nov. 8, 2002, with weighing all animals on-test.
Represented in the test were 192 calves (eight head/pen x 24 pens) from
12 different producers from six different counties throughout southwest
North Dakota. This weight was used as the baseline for all performance
and economic analysis of the 56-day test. One weigh period at 28 days was
used to aid in tracking economic and animal performance while
providing report information to cooperating producers. The test period ended
Jan. 3, 2003.
All pens of cattle were independently and anonymously valued by
two qualified individuals based on weight on-test the market as of Nov. 8,
2002, previous management prior to receiving in the yard
(weaning, vaccinations, etc.), cattle representative of a larger saleable group,
weight off-test, and the market as of Jan. 3, 2003.
The backgrounding ration consisted of a barley-pea haylage and
whole corn base with a locally produced mineral/protein supplement (Table
1). Pen feed adjustments were based on individual bunk calls prior to
cattle being fed once daily (9 a.m.). Upon receiving into the backgrounding
lot, cattle were provided a seven- to 10-day feed acclimation period
before starting the backgrounding test. Custom feeding fees were charged
to the cooperating producers according to a signed custom feeding agreement.
Animals were individually weighed prior to the morning feeding for
on-test, 28-day interim and off-test weights. A health protocol
was established through a local veterinary clinic including a monthly pen
walk-through by the attending veterinarian.
Data collection and reporting to cooperating producers included individual
calf weights for the three weigh periods, ADG, pen feed consumption and feed
conversions, cost of gain, breakeven projections and pen close-outs based on
independent valuation of calves.
Table 1. Southwest Feeders 2002 Backgrounding Diet.
---------------------------------------------------------------------
Total Diet Barley-Pea
(calculated) Haylage Corn Supplement
---------------------------------------------------------------------
% of diet, DM basis 100.00 73.50 21.50 5.50
% DM 45.90 38.90 88.60 91.70
Protein, % 13.60 13.80 11.40 20.00
NEm, Mcal/lb 0.83 0.68 0.99 0.62
NEg, Mcal/lb 0.47 0.41 0.68 0.35
Ca, % 0.72 0.56 0.02 5.50
P, % 0.36 0.33 0.34 0.84
Cu, ppm 21.00 5.00 3.00 308.00
Zn, ppm 82.00 27.00 29.00 1007.00
Mn, ppm 75.00 33.00 11.00 880.00
Deccoxa 125 mg 125 mg
Rumensinb 200 mg 200 mg
---------------------------------------------------------------------
aDeccox fed from 11/1/02 to 12/2/02
bRumensin fed from 12/3/02 to 1/9/03
Results and discussion
Cattle averaged 583 lbs at the start of the backgrounding test (192
head). After a 56-day feeding period, average daily gain was 2.76 lbs/day for an
off-test weight of 737 lbs. Average daily intake per head was 16.55 lbs
(dry matter basis) for a feed conversion of 6.14 lbs per pound of gain (dry
matter basis) (Table 2).
Overall feed cost per pound of gain was $0.28. Total cost of gain
including yardage, processing, death loss and interest was $0.42. Yardage cost
was $0.25 per head per day and processing expenses averaged $4.50 per
head. Death loss for the whole yard was 0.5%. While death loss had
minimal impact across all pens, it had a negative impact (-$39.24/head) on
the return of the particular pen (Figure 1). The average value of all cattle
on-test was $83.50/cwt. and an off-test value of $82.98/cwt. Calculated
net return per head for the overall trial was $54.30 (Table 3).
In addition to the $54.30 per head net return to the overall livestock enterprise,
net return per acre of crop ground is important in the analysis of the locally
produced barley-pea haylage. Forage production of the barley-pea haylage occurred
in 2000 and it was stored in haylage bags. Based on a production of 5.9 ton/acre
(38.9% DM) and a feed value of $26/ton (as-fed), the barley-pea haylage had
a gross return of $153/acre. With production and harvesting costs of $120/acre
(based on custom charges), net return per acre for the barley-pea haylage was
$33/acre.
Table 2. Feeding performance of all pens combined.
----------------------------------------------------
0-28 d 28-56 d 0-56 d
----------------------------------------------------
DMI, lbs 16.03 17.07 16.55
DMI, %BW 2.56 2.42 2.50
F:G, (feed:gain) 5.08 7.66 6.14
Feed cost of gain, $/lb 0.23 0.34 0.28
ADG, lb/d 3.16 2.37 2.76
----------------------------------------------------
Table 3. Feeding close-out on all pens for 56 day test. (Click
here for a 22KB Adobe Acrobat pdf file.)
Figure 1. Net return per head by pen for 56 day backgrounding test.
(Click here for a 15KB black and white graph.)
Figure 2. Average daily gain by pen for total 56 day backgrounding test.
(Click here for a 26KB black and white graph.)
Implications
Results of the 2002 calf backgrounding test provided
favorable information to cooperating producers and a positive first year for
Southwest Feeders. Opportunities exist for producers interested in
background-ing calves in southwest North Dakota as shown by the overall positive
net return. The weather through the feeding test provided
above-normal temperatures and the cattle market provided for
higher-than-anticipated returns. In addition to returns to
the livestock operation, added value to forage crops through livestock
feeding adds to the income potential in diversified operations. The
coming year will provide the opportunity to present these findings to
additional producers through group and farm/ranch visits.
1Hettinger
Research Extension Center, Hettinger, ND
2Dickinson Research
Extension Center, Dickinson, ND
INDEX
Effect of field pea level on intake, digestion, microbial
protein synthesis, ruminal fermentation and fill in beef steers fed growing
diets
J.J. Reed1, G.P.
Lardy1, M.L. Bauer1, J.S.
Caton1 and T.C. Gilbery1
Objectives were to evaluate the effects of an increasing level of field
peas on intake, digestion, microbial protein synthesis and ruminal fermentation
in beef steers fed growing diets. Because of their relatively high level
of protein, including field peas in growing diets will reduce the need for
protein supplementation and may reduce feed costs. It appears that field
pea is a suitable substitute for corn in growing diets.
The effects of increasing the level of field pea (var: Profi) on intake,
digestion, microbial protein synthesis, and ruminal fermentation were evaluated
in beef steers fed growing diets. Four ruminally and duodenally cannulated crossbred
beef steers (807 ± 106 lb initial BW) were used in a 4 x 4 Latin square
design. The control diet consisted of 50% corn, 23% corn silage, 23% alfalfa
hay and 4% supplement (DM basis). Field pea replaced corn at 0, 33, 67, and
100%, forming the treatments. Diets were formulated to contain a minimum of
12% CP, 0.62% Ca, 0.3% P and 0.8% K (DM basis). Each period was 14 days in length.
Steers were adapted to the diets for nine days. On days 10 to 14, intakes were
measured. Field pea was incubated in situ and ruminal fluid was collected and
pH recorded. Duodenal samples were taken for three consecutive days. Linear,
quadratic and cubic contrasts were used to compare treatments. There were no
differences in DMI (P > 0.46). Ruminal dry matter fill (P =
0.02) and mean ruminal pH (P = 0.01) decreased linearly with an increasing
level of field pea. Total tract disappearance of OM (P = 0.001), N (P
< 0.001) and NDF (P = 0.004) increased linearly with an increasing
level of field pea. There were no differences observed in total tract disappearance
of starch (P = 0.5) or ADF (P = 0.27). Ruminal disappearance of
N corrected for microbial matter (P = 0.02) and ruminal disappearance
of NDF (P = 0.004) increased linearly with an increasing level of field
pea. There were no differences in ruminal disappearance of OM (P = 0.9),
starch (P = 0.77) or ADF (P = 0.77). In situ rumen degradability
of field peas responded cubically (P = 0.04) as it increased from 0 to
33, decreased from 33 to 66, and increased from 66 to 100% field pea inclusion.
Because of their relatively high level of protein, including field peas in growing
diets will reduce the need for protein supplementation and may reduce feed costs.
It appears that field pea is a suitable substitute for corn in growing diets.
Introduction
Field pea (Pisum sativum) production in North Dakota has
increased dramatically from approximately 14,000 acres in 1994 to 89,000
acres in 2001 (NDASS, 2001). The reasons for this increase in acreage are
several fold. Field peas are adapted to the Northern Great Plains, use
conventional equipment and fix nitrogen in the soil (Anderson, 1998).
Annual legumes complement crop rotations by expanding the number of
crops available to small-grain producers to avoid problems associated
with continuous small-grain cropping. These problems include soil
erosion, disease, poor soil structure and pests (Martin and Leonard, 1967).
Human consumption is the dominant market for pea producers;
however, the feed industry is an excellent potential market for peas
(Corbett, 1994). Until recently, there has been a lack of information available on
the nutritive attributes of feeding peas to ruminants.
Much recent research has focused on feeding field peas in growing
and finishing rations. Researchers have reported similar dry matter
intakes when field peas replaced cereal grains in growing diets (Anderson,
1999; Poland and Landblom, 1996). Okine (2001) reported increased
gain:feed ratio (G:F) when field peas replaced barley and soybean meal in
growing diets. Poland and Landblom (1996) reported no difference in G:F
when field pea replaced barley and soybean meal in 33% concentrate diets
while replacement with field peas in 77% concentrate diets decreased G:F.
Flatt and Stanton (2000) replaced corn with field peas at 5, 10 and 20% in
86% concentrate finishing diets. Dry matter intake decreased linearly,
and G:F increased linearly. Birkelo et al. (2000) replaced 10% of corn
with field peas in 77% concentrate finishing diets. Inclusion of field
peas increased ADG and G:F over the first 56 days of the trial, however,
there were no differences between treatments over the entire trial.
There were also no differences in carcass characteristics.
Limited research has been conducted on the effects of field peas on digestion,
microbial protein synthesis, ruminal fermentation and fill. Research is this
area is warranted. Therefore, the objectives of this research were to evaluate
the effects of an increasing field pea level on intake, digestion, microbial
protein synthesis, ruminal fermentation, and fill in beef steers fed growing
diets based on corn, corn silage and alfalfa hay.
Procedures
Four ruminally and duodenally cannulated beef steers were used in a 4 x 4
Latin square design. Steers were housed in an enclosed barn in individual tie
stalls. Animals were allowed ad libitum access to water and diets. The control
diet consisted of 50% rolled corn, 23% corn silage, 23% alfalfa hay and 4% supplement
(DM basis). Rolled field pea replaced rolled corn at 0, 33, 67 and 100% (DM
basis), forming the treatments (Table 1). Diets were formulated to contain a
minimum of 12% CP, 0.62% Ca, 0.3% P and 0.8% K (DM basis). Steers were fed twice
daily at 12-hour intervals.
Each experimental period was 14 days in length. Feed and feed refusal samples
were collected on days 10 to 14 to determine dry matter intake. Duodenal fluid
samples were collected on days 10 to 13 to estimate flow of nutrients from the
rumen to the small intestine. Fecal collections took place on days 10 to 13
to estimate total tract digestion. Rolled field peas were incubated in the rumen
via in situ bags on days 10 to 13 to estimate degradation of field peas in the
rumen. On day 13 of each period, ruminal fluid samples were collected and analyzed
for pH, NH3-N, and VFA. Ruminal evacuations were conducted on day
14 of each period to determine ruminal dry matter fill.
Table 1. Diet composition, analyzed dietary nutrient content,
and IVOMD.
---------------------------------------------------------------
Treatments
------------------------------------
Item 0 33 67 100
---------------------------------------------------------------
Ingredient, % of DM
Dry-rolled corn 50.000 33.500 16.500 0.000
Rolled field Pea 0.000 16.500 33.500 50.000
Corn silage 23.000 23.000 23.000 23.000
Alfalfa hay 23.000 23.000 23.000 23.000
Fine ground corn 2.350 2.350 2.350 2.350
Limestone 0.496 0.496 0.496 0.496
Urea 0.437 0.437 0.437 0.437
Salt 0.300 0.300 0.300 0.300
Molasses 0.160 0.160 0.160 0.160
Dicalcium phosphate 0.212 0.212 0.212 0.212
Trace mineral premixa 0.020 0.020 0.020 0.020
Vitamin E premixb 0.020 0.020 0.020 0.020
Vitamin A:D premixc 0.005 0.005 0.005 0.005
Analyzed dietary nutrient content
DM, % 76.16 76.49 76.83 77.16
- - - - - - - % DM - - - - - - - - -
OM, % 88.65 89.55 90.48 91.38
CP, % 14.54 17.02 19.57 22.05
Starch, % 47.18 42.77 38.21 33.8
NDF, % 20.59 20.59 20.58 20.58
ADF, % 12.88 13.05 13.23 13.41
Calcium, % 0.92 0.92 0.93 0.94
Phosphorus, % 0.36 0.39 0.43 0.46
IVOMD, % 79.71 80.11 80.52 80.91
---------------------------------------------------------------
aContained 30,005 mg/kg Cu; 48,008 mg/kg Fe; 2776 mg/kg I;
180,034 mg/kg Mn; and 563 mg/kg Zn.
bContained 44 IU vitamin E/kg premix.
cContained 48396 IU vitamin A/kg premix and 4620 IU vitamin
D/kg premix.
Results and Discussion
There were no differences in dry matter intake (DMI) between
the treatments (P = 0.46, Table 2). There was a linear decrease
(P = 0.02) in ruminal dry matter fill with
an increasing field pea inclusion. Ruminal dry matter fill is highly
dependent on passage rate, digestion rate, and DMI (Bodine et al., 2000).
Since there was no difference in DMI between the treatments,
increasing levels of field peas may be increasing digestion rate.
There was no difference (P = 0.84) in organic matter intake (OMI)
between the treatments (P = 0.84, Table 2). There were no differences in
organic matter digestion in the rumen or intestine
(P > 0.40). However, total tract organic matter
disappearance increased (P = 0.004) with
increasing field pea inclusion. This data suggests that the organic matter of field
peas may be more digestible than that of corn in the total digestive tract.
Nitrogen intake increased linearly (P < 0.001) with an increasing
field pea inclusion because field peas are higher in protein that corn (Table
2). Total N (P = 0.02) and ammonia nitrogen (P < 0.001) flow
to the small intestine increased with an increasing field pea inclusion. Therefore,
there was more nitrogen available for absorption in the small intestine with
increasing level of field pea. Bacteria N (P = 0.41) flow to the small
intestine was not affected.
Starch intake (P = 0.001) and flow to the small intestine
(P = 0.008) decreased linearly with
increasing field pea inclusion (Table 2). The decreases in starch intake and flow
to the small intestine were not unexpected since the corn was higher
in starch than the field peas (72.36 vs 47.03%). There were no
differences in starch digestion relative to intake in the rumen, intestine, or
total digestive tract (P > 0.50).
There was no difference in neutral detergent fiber intake (NDF)
(P = 0.15) with an increasing field pea inclusion (Table 2). Ruminal
NDF disappearance was not affected (P = 0.21) by an increasing level of
field peas. Total tract NDF disappearance increased linearly
(P = 0.004) and quadratically (P = 0.04) with
increasing field pea inclusion.
Acid detergent fiber (ADF) intake was not affected
(P = 0.43) by an increasing field pea inclusion (Table
2). Ruminal ADF disappearance was not affected
(P = 0.77) by an increasing inclusion of field peas. Intestinal
ADF disappearance (% of intake) tended to increase linearly
(P = 0.08) and quadratically (P = 0.06) with
an increasing field pea inclusion. Total tract ADF disappearance was
not affected (P = 0.27) by an increasing level of field peas.
Mean ruminal pH decreased linearly (P = 0.009) with an
increasing inclusion of field pea (Table 2). Low rumen pH values are associated
with digestive upsets such as acidosis. However, acidosis was not an issue
in our study because diets contained a considerable amount of
roughage (34.5%) and the lowest average pH value was 6.43. Ruminal pH of
5.6 and 5.2 is often used as benchmarks for chronic and acute acidosis
(Owens et al., 1998).
Ruminal ammonia nitrogen (NH3-N) increased
(P < 0.001) with an increasing inclusion of field pea (Table
2). The increase in ruminal NH3-N was not unexpected and is related to
the increased dietary CP level as field pea level increased in the diet.
Adequate ruminal NH3-N concentrations
are important for microbial growth and function in the rumen. Ruminal
NH3-N values for all of the diets were above the recommended levels
for maximum microbial growth (0.97 to 2.42 mM) suggested by Satter
and Slyter (1974).
Total ruminal VFA concentrations increased linearly and cubically
(P = 0.01) with an increasing inclusion of field pea (Table 2). Volatile fatty
acids are a major end product of ruminal fermentation; therefore, our
data indicate that increasing the inclusion of field pea increases ruminal
fermentation.
In situ rumen degradability of field pea responded cubically (P = 0.04)
as it did not change between 0 and 33%, decreased from 33 to 67%, and increased
from 67 to 100%.
Table 2. Effect of an increasing level of field pea inclusion on intake,
digestion, and ruminal characteristics.
----------------------------------------------------------------------------------
Field pea
replacement of corn, % Contrastsa
-------------------------- --------------------
Item 0 33 67 100 SEM L Q C
----------------------------------------------------------------------------------
Intake
Dry matter, lb/d 28.16 26.99 27.43 27.02 0.55 0.27 0.51 0.35
Organic matter, lb/d 24.90 24.31 24.99 24.86 0.57 0.83 0.71 0.45
Nitrogen, lb/d 0.57 0.66 0.76 0.86 0.02 <0.001 0.77 0.73
Starch, lb/d 13.36 11.80 9.98 9.51 0.53 0.001 0.34 0.52
NDF, lb/d 6.44 6.22 6.84 6.42 0.16 0.49 0.54 0.04
ADF, lb/d 4.02 4.01 4.2 4.4 0.18 0.14 0.61 0.79
True ruminal
disappearanceb,
% of intake
Organic matter 84.4 84.6 85.1 85.1 0.8 0.51 0.90 0.84
Nitrogen 72.7 77.0 78.1 78.7 1.4 0.02 0.24 0.68
Starch 91.1 91.6 91.2 92.8 1.3 0.45 0.66 0.63
NDF 76.3 77.7 80.1 78.9 1.5 0.09 0.31 0.42
ADF 77.2 77.9 76.4 78.7 1.6 0.69 0.64 0.43
Bacterial crude
protein synthesis
g N/kg of OMDTc 7.3 7.5 7.5 8.1 0.5 0.27 0.74 0.70
Apparent total tract
disappearance, %
Organic matter 84.5 86.0 86.6 86.7 0.3 0.001 0.05 0.72
Nitrogen 80.5 83.4 84.9 85.6 0.6 <0.001 0.09 0.85
Starch 96.7 97.1 96.9 97.6 0.4 0.23 0.67 0.44
NDF 70.1 74.1 76.2 75.5 0.9 0.004 0.04 0.78
ADF 67.3 70.1 69.5 70.6 11.1 0.11 0.50 0.36
Rumen Characteristics
Dry matter fill, % BW 1.84 1.55 1.30 1.35 0.12 0.02 0.18 0.63
pH 6.68 6.69 6.45 6.62 0.03 0.01 0.02 <0.001
NH3-N, mM 2.40 3.39 5.30 8.18 0.25 <0.001 <0.001 0.96
Total VFA, mM 71.32 72.03 92.59 84.20 3.16 0.01 0.20 0.01
----------------------------------------------------------------------------------
aL = linear, Q = quadratic, and C = cubic.
bCorrected from OM of bacterial origin.
cOMDT = true OM disappearance.
Conclusions
An increasing level of field pea inclusion in growing diets does
not affect DMI or bacterial CP synthesis. Increasing levels of field peas
in growing diets increases ruminal, intestinal, and apparent total
tract digestion of N; and increases apparent total tract digestion of
OM, starch, and NDF. Field peas do not influence ADF digestion
when replacing corn in growing diets. An increasing level of field pea
inclusion increases ruminal NH3-N and
total VFA concentration, and decreases ruminal pH.
Implications
With high protein and energy levels, field pea can be an excellent
ingredient in livestock diets. Our research indicates that field pea is a
suitable substitute for corn in growing diets and may reduce the need for
protein supplementation because of its high protein content. Cost and
availability are factors that should also be
considered when formulating rations to include field peas.
Literature Cited
Anderson, V.L. 1998. Field peas in creep feed for beef calves. Carrington
Research Extension Center's Beef and Bison Production Field Day Report. p.
17-19. North Dakota State University Agriculture Experiment Station, Fargo.
Anderson, V.L. 1999. Field peas in diets for growing and finishing steer
calves.
Carrington Research Extension Center's Annual Research Report. p. 9-15. North
Dakota State University Agriculture Experiment Station, Fargo.
Birkelo, C.P., B.J. Johnson, and B.D. Rops. 2000. Field peas in finishing
cattle diets and the effect of processing. SDAES Cattle 00-4. South Dakota
State University Extension Service, Brookings.
Bodine, T.N., H.T. Purvis, II, C.J. Ackerman, and C.L. Goad. 2000. Effects
of supplementing prairie hay with corn and soybean meal on intake, digestion,
and ruminal measurements by beef steers. J. Anim. Sci. 78:3144-3154.
Corbett, R. 1994. Feeding peas to cattle. Page 16 in Canadian Peas. Feed
industry guide. D. Hickling, ed. Can. Special Crops Association. Winnepeg,
Manitoba, Canada.
Flatt, W.R. and T.L. Stanton. 2000. Effect of Profi peas, Pisum arvense,
on growth performance and carcass characteristics of feedlot cattle. Colorado
State University Animal Sciences Research Report. p. 81-84. Colorado State
University, Fort Collins.
Martin, J.H. and W.H. Leonard. 1967. Fertilizer, green manuring, and rotation
practices. Page 145 in Principles of Field Crop Production. The MacMillian
Company, New York.
North Dakota Agriculture Statistics Service. 2001. North Dakota Agricultural
Statistics 2001. No. 70. North Dakota State University, Fargo.
Okine, E. 2001. Feeding peas to backgrounding cattle. Western Forage/Beef
Group. 5:4.
Owens, F.N., D.S. Secrist, W.J. Hill, and D.R. Gill. 1998. Acidosis in cattle:
a review. J. Anim. Sci. 76:275-286.
Poland, W.W. and D.G. Landblom. 1996. Feeding value of field pea and hull-less
oat in growing calf diets. J. Anim. Sci. 74 Suppl 1:279.
Satter, L.D. and L.L. Slyter. 1974. Effects of ammonia concentration on rumen
microbial protein production in vitro. Br. J. Nutr. 32:199-208.
1Department
of Animal and Range Sciences
INDEX
Determining an optimum stocking rate for the Missouri
Coteau of North Dakota
Bob D. Patton1
The objective of this study is to determine the stocking rate that would
result in the greatest long-term economic return to the livestock producer.
In the past 12 years of this study the stocking rate that would have resulted
in the greatest return was 1.76 AUM/acre. However for a number of reasons
we feel this stocking rate may be too heavy to recommend.
This study compares the effects of five different grazing intensities on
the plant community, livestock performance and economic returns.
The stocking rate which provides the maximum pounds of beef/acre
is generally higher than the stocking rate which produces the
maximum economic return. The stocking rate with the highest return is higher
than the one which produces the maximum pounds of forage per acre. Also,
there is still some question regarding the sustainability of livestock
performance under the heavy stocking rates.
Introduction
A grazing intensity research project was initiated at the Central
Grasslands Research Extension Center (CGREC) in 1989. The objectives are
to determine the effect of grazing intensity on livestock
performance and profitability and its effect on
the sustainability of forage production. Only the effect on livestock
performance is discussed in detail in this paper.
Procedure
Five treatments are included: no grazing, light, moderate, heavy
and extreme grazing. Each treatment is replicated three times in pastures
of about 30 acres each except that the no grazing treatment consists of six
0.3-acre enclosures placed on both overflow and silty range sites.
Livestock are not rotated between pastures and each pasture receives the
same treatment each year. We try to stock the pastures each year so that
when the cattle are removed in the fall, 65%, 50%, 35% and 20% of
the forage produced in an average year is remaining on the light,
moderate, heavy and extreme treatments, respectively. For these pastures
that means 2,063 lbs/acre, 1,623 lbs/acre, 942 lbs/acre, and 484 lbs/acre,
of forage remains on the light, moderate, heavy and extreme pastures,
respectively. Open heifers have been used to stock the study since 1994; prior
to that bred heifers or steers had been used. Adjustments in
stocking pressure are made each year based on information from previous years
to better match our desired grazing intensities. The cattle are
weighed before they go on pasture and when they are removed. A dollar value
is assigned to each animal based on its weight and the regression
relationship which was developed using weight and sale prices from local
livestock auctions during the week the animals went on or were removed from
the pasture. When comparing estimated economic returns from
selected stocking rates, costs for land, labor and management are not
included because they vary greatly from one operation to another.
Regression relationships were determined each year between stocking rate
and average daily gain, gain per acre and economic return per acre.
Results and Discussion
Table 1 shows the average daily gain, gain per acre and body condition scores
from the different grazing intensities for the last five years, average gains
by treatment from 1991 to 2002 and average body condition from 1994 to 2002.
Grazing pressure was too light on the heavy and extreme treatments in the first
two years of the study so there are no significant differences in average daily
gains in 1989 and 1990. Following that year, average daily gain and animal body
condition scores decrease with increasing grazing intensity. The rate at which
average daily gain decreases with an increase in stocking rate varies greatly
from year to year. The differences between years may be due to variation in
forage quality or quantity, the effect of weather on the animals, their initial
weight or their potential to gain. In years when the grazing season ends early,
as in 2000 to 2002, there is less chance for the differences in rate of gain
between the light and extreme treatments to become significant.
Table 1. Average daily gains, gains per acre, and condition scores
from different stocking intensities.
------------------------------------------------------------------
Average Daily Gains (lbs/head/day)
Desired ----------------------------------------------------
Grazing Average
Intensity 1998 1999 2000 2001 2002 1991-2002
------------------------------------------------------------------
Light 1.53a1 1.40a 1.12 1.44 1.34 1.39a
Moderate 1.31ab 1.30a 1.07 1.29 1.47 1.27a
Heavy 1.03b 1.19ab 0.97 1.23 1.00 1.11b
Extreme 0.60c 0.96ab 0.82 1.14 0.78 0.77c
LSD2 (0.05) 0.38 0.25 NS3 NS NS 0.16
------------------------------------------------------------------
Average Gain (lbs/acre)
----------------------------------------------------
Average
1998 1999 2000 2001 2002 1991-2002
------------------------------------------------------------------
Light 28.29c 36.50b 33.03c 43.18c 20.06 24.39c
Moderate 62.25b 59.73b 42.39bc 59.88bc 37.90 48.51b
Heavy 97.86a 93.93a 58.24ab 67.15b 33.57 77.13a
Extreme 67.98b 108.49a 74.44a 108.27a 38.96 81.35a
LSD (0.05) 29.59 24.31 17.52 23.74 NS 12.73
------------------------------------------------------------------
Condition Score
----------------------------------------------------
Average
1998 1999 2000 2001 2002 1994-2002
------------------------------------------------------------------
Light 5.81a 5.72a 5.18a 5.78 5.22 5.39a
Moderate 5.71ab 5.65ab 5.20a 5.52 5.18 5.29ab
Heavy 5.21b 5.54bc 5.01a 5.43 5.18 5.13b
Extreme 4.65c 5.41c 4.61b 5.24 5.05 4.78c
LSD (0.05) 0.53 0.18 0.31 NS NS 0.21
------------------------------------------------------------------
1Means in the same column followed by the same letter are not
significantly different at p=0.05.
2LSD=least significant difference.
3Means not significantly different.
Initially, gain/acre increases as the stocking rate increases but
there comes a point when further increases in stocking rates result in
reduced gain/acre. All years except 2001 had at least one observation of a
stocking rate higher than the rate projected to give the maximum gain/per acre
for the year. Since we can't predict ahead of time what stocking rate would
give the maximum gain/acre in a particular year, it would be impossible
to stock each year for maximum gain/acre. In retrospect, if we were to
pick one stocking rate that would have resulted in the maximum
gain/acre over this 12-year period it would have been 2.14 AUM/acre. We predict
that if we had stocked at this level each year, gain per acre would have
ranged from a loss of 44.6 lbs/acre in 2002 to a gain of 148.9 lbs/acre in
1993 with an average of 78.3 lbs/acre. Because so little forage was
produced in 2002, the grazing season was cut short and none of the pastures
were actually stocked that heavily.
If cattle prices were constant, then return/acre would peak at a stocking rate
somewhere below maximum gain/acre with the exact point depending on carrying
costs (interest, death loss, salt and mineral, vet cost, transportation, labor
and land). However, when cattle are worth more per hundredweight in the spring
than they are in the fall it causes the point of maximum return/acre to occur
at a lower stocking rate. When they are worth more in the fall, it causes the
maximum return to occur at a higher stocking rate. Obviously we can't know ahead
of time what the optimum stocking rate for a particular year is going to be.
If we were to pick one constant stocking rate that would have provided the maximum
return/acre over this last 12-year period it would have been 1.76 AUM/acre.
Although the average return per acre is higher under the optimum rate there
were four years with negative returns while only one year had a negative return
under the moderate stocking rate. (Costs for land, labor and management have
not been subtracted). In all but three years (1992, 1996 and 1999), the stocking
rate with the greatest economic return was less than the rate with the greatest
gain per acre.
Recommendations
Results of the past 12 years indicate that the stocking rate that would have
provided the greatest return was 1.76 AUM/acre. However, for a number of reasons
we feel this stocking rate may be too heavy to recommend. First, the extreme
and heavy grazed pastures have been deteriorating in condition through the course
of the study and may not be able to support the rates of gain we have seen in
the past. Also, we have had higher-than-average precipitation through much of
this period. The average annual precipitation for the first 13 years of this
study was 19.06 inches compared to the 51-year average of 17.99 inches. As we
move into a period of drier weather, forage production and annual gains are
reduced. Both profits and losses are higher at higher stocking rates depending
on the difference between spring and fall livestock prices. The producer would
experience more years with negative returns at the higher stocking rates.
It appears that the moderate stocking rate may be too conservative if maximizing
profit is the objective. In only three out of 12 years, returns would have been
higher with a stocking rate less than the moderate rate of 0.96 AUM/acre. In
all other years, a higher stocking rate would have resulted in higher returns.
For a stocker operation in this area, the optimum stocking rate would fall in
the range of 0.96 to 1.76 AUM/acre. In lower rainfall areas farther west in
the state, these values would be reduced.
These stocking recommendations cannot be applied to a
cow-calf operation because calf gains are largely dependent on the cows'
milk production. Higher stocking rates could reduce the cows' condition
and conception rates and result in higher overwintering costs to bring the
cows back to condition to calve in the spring.
More information on this and other research conducted at the Central Grassland
Research Center is available at: http://www.ag.ndsu.nodak.edu/streeter/
1NDSU Central Grasslands
Research Extension Center
NEXT | INDEX
|
