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Growth-Performance and Shrink by Stocker Calves Grazing Bermudagrass
Pastures and Fed Different Levels of Grain Sorghum
K. Coffey, 1 W. K. Coblentz, 1 and G. Montgomery 2
Story in Brief
A 48-day grazing study was conducted to evaluate the effect of feeding no supplemental grain sorghum or ground grain
sorghum at 0.5 or 1% of body weight (BW) on growth-performance and shrink by stocker cattle grazing bermudagrass
in the summer. A total of 72 mixed-breed stocker steers and heifers (490±8.4 lb) were allocated randomly by weight and
sex into nine groups and grazed bermudagrass pastures from June 29 until August 16, 2000. Calves were fed 0, 2.5, or
5 lb/day of ground grain sorghum on Monday through Friday. Calves fed 5 lb/day of grain sorghum were heavier (P <
0.10) than calves from the other groups, and had faster (P = 0.11) weight gain (0.43 lb/day) than those fed no grain. Gain
by calves fed 2.5 lb/day grain were numerically improved (0.12 lb/day) compared with calves fed no grain, and numerically
lower (0.31 lb/day) than from calves fed 5 lb/day, but did not differ statistically (P > 0.11) from either group.
Supplemental grain level did not affect (P > 0.10) calf shrink. Therefore, supplemental grain fed at 1% of BW may be
used to improve weight gain by calves grazing bermudagrass during the summer, but conversion efficiencies should be
considered to determine if the supplement is economical or not.
Introduction
Grains are often fed to grazing cattle to improve rate of
gain. Calf gains may be improved substantially during lateseason
grazing of bermudagrass by supplementation with low
levels of grain (Gunter and Phillips, 1998), but those gains
may still be lower than desired. When supplemental grain
levels reach approximately 0.5% of body weight, forage
intake may be suppressed (Lusby and Horn, 1991), leading to
inefficient conversion of the supplemental grain to additional
body weight gain. However, without the additional energy
supplementation, gains may not be adequate to reach marketing
objectives of the producer. The objective of this study was
to compare growth-performance by stocker cattle grazing
bermudagrass and fed different levels of grain sorghum.
Experimental Procedures
Seventy-two mixed-breed stocker steers and heifers
were received at the University of Arkansas Southeast
Research and Extension Center in Monticello on June 16,
2000 and had received respiratory and clostridial vaccinations
and a growth-promoting implant prior to arrival at the
station. Calves initially grazed a bermudagrass pasture as a
group. Calves were weighed on June 28 and 29 without prior
removal from pasture and water, were stratified by weight
and sex, and allocated randomly to one of nine groups. The
groups were then allocated randomly to receive no grain
sorghum (0GS), or 2.5 (2.5GS) or 5 lb/d (5GS) Monday
through Friday of ground grain sorghum. These levels were
chosen to represent feeding grain at either 0.5, or 1% of body
weight. Groups of calves were then allocated randomly to one
of nine bermudagrass pastures for a 48-day study.
All calves were offered free-choice access to a commercial
mineral mix containing lasalocid. Pastures were fertilized
with a complete commercial fertilizer to provide 50
lb/acre of each of N, P2O5, and K in late May and 50 lb/acre
N in early July.
Calves were weighed on July 27 without prior removal
from pasture and water for an intermediate weight. On
August 16 beginning at 0700 h, calves on 2.5GS and 5GS
treatments were fed their respective supplement amounts,
were allowed to consume the supplement, and were then
removed from pasture along with 0GS calves. They were
immediately weighed, then placed in small pens without feed
or water. Calves were weighed at 2-hour increments through
the following 10-hour period to determine the impact of grain
supplement level on subsequent shrink.
All animal weight and shrink data were analyzed statistically
using SAS (SAS Institute, Inc., Cary, NC.) procedures
for a completely randomized design.
Results and Discussion
Final body weight was heavier (P < 0.10) from calves
fed 5GS than those on 0GS or 2.5GS treatments (Table 1).
Total gain tended to be greater (P = 0.11) from calves fed 5GS
than from those on 0GS, but gain from calves fed 2.5GS did
not differ (P > 0.11) from those on either 0GS or 5GS. At
1 Department of Animal Science, Fayetteville
2 Southeast Research and Extension Center, Monticello
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