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Arkansas Animal Science Department Report 2001
these levels of gain, the conversion efficiencies were 14.9 and
8.3 lb of supplemental grain required to produce an additional
pound of gain from 2.5GS and 5GS, respectively. These
conversion efficiencies are somewhat better than observed in
a previous study from feeding grain sorghum at 1% of BW
(9.5 lb/lb; Galloway et al. 1993a), but are worse that from
another study from feeding corn at .5% of BW to calves grazing
bermudagrass pastures (6.1 lb/lb; Galloway et al. 1993b).
The rate of shrink (%/hour) during the period between
2 and 4 hours after removal from pasture was lower (P < 0.10)
from calves on the 5GS treatment than from calves on the
0GS or 2.5GS treatments (Table 2). However, total weight
loss over the entire 10-hour period (lb and % of initial body
weight) did not differ (P > 0.10) among treatments.
Therefore, feeding supplemental grain sorghum to
calves grazing bermudagrass pastures during the late grazing
season improved weight gain, but conversion efficiencies
were poor making the economic efficiency questionable. In
order for the calves to gain approximately 2 lb/day during the
late grazing season, it was necessary to feed them 25 lb of
ground grain sorghum each week (5GS). Feeding grain
sorghum prior to a period of feed and water deprivation did
not impact cattle shrink over a 10-hour period.
Implications
In order to achieve body weight gains in excess of 1.5
lb/day in a typical summer grazing period from calves on
bermudagrass pastures, supplements must be fed. Feeding at
levels at or above 0.5% of body weight should improve animal
gain, but conversion efficiencies may limit economic
benefits of the supplementation. Feeding ground grain
sorghum immediately prior to removing calves from
bermudagrass pastures should have minimal impact on body
weight loss during a period of feed and water deprivation.
Literature Cited
Galloway, D. L., et al., 1993a. J. Anim. Sci. 71:1288.
Galloway, D. L., et al., 1993b. Prof. Anim. Scientist 9:173.
Gunter, S., and M. Phillips. 1998. AR. Agric. Exp. Sta. Rept.
464. pp. 93-95.
Lusby, K.S., and G.W. Horn. 1991. Prof. Anim. Scientist
7:43.
Table 1. Growth performance by stocker steers grazing bermudagrass pastures
and fed different levels of ground grain sorghum.
Level of ground grain sorghum, lb/day M-F
Item 0 2.5 5 SE
Initial weight, lb 490 489 492 1.2
Weight – d 29, lb 523 522 535 4.2
Final weight, lb 562 b 567 b 584 a 5.7
Total gain, lb 72 d 78 cd 92 c 5.9
Daily gain, lb 1.49 d 1.61 cd 1.92 c 0.123
Feed/additional gain, lb/lb - 14.9 8.3 -
a,b Means within a row without a common superscript letter differ (P < 0.10).
c,d Means within a row without a common superscript letter differ (P = 0.11).
Table 2. Weight loss during a 10-h drylot shrink by stocker steers fed different
levels of ground grain sorghum.
Level of grain sorghum, lb/day M-F
Item 0 2.5 5 SE
Shrink, %/h
0-2 h 1.32 1.44 1.47 0.279
2-4 h 0.98 a 1.06 a 0.56 b 0.127
4-6 h 1.13 0.84 1.38 0.207
6-8 h 0.61 0.63 0.62 0.112
8-10 h 0.17 0.53 0.31 0.153
Total weight loss, lb 45 51 49 1.7
Total weight loss, % 9.8 10.1 10.0 0.13
a,b Means within a row without a common superscript letter differ (P < 0.10).
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