K.B. ADDISON1, D.G. CAMERON2 and G.W. BLIGHT3
1Formerly Queensland Department of Primary Industries, Brian Pastures Pasture Research Station, Gayndah, 4625.
2Queensland Department of Primary Industries, Brisbane, 4000.
3Queensland Department of Primary Industries, Rockhampton, 4700.
The effects of supplements formulated from cottonseed meal, sorghum meal and biuret and balanced for either nitrogen or energy content were examined in two separate trials using weaner Hereford steers grazing native speargrass pastures.
In Trial 1, with equal nitrogen contents, the steers received Nil, 680
g cottonseed meal, 318 g cottonseed meal + 318 g sorghum meal + 44 g
biuret or 597 g sorghum meal + 83 g biuret head-1 day-1
from May to November 1969 and again from March to May 1970. From November
to March they grazed unsupplemented green panic pastures as one herd.
Cottonseed meal was the superior supplement over both supplementation
periods with liveweight gains of 60.9 and 29.2 kg head-1,
respectively, compared with 10.5 and 14.5 kg head-1, respectively,
for unsupplemented animals. Sorghum meal plus biuret gave gains of 29.8
and 19.6 kg head-1, respectively, and was useful for bodyweight
maintenance when faecal nitrogen levels were below 1.3%. Sorghum meal
plus biuret was not an effective substitute for half the nitrogen in
cottonseed meal and produced gains of only 37.5 and 26.4 kg head-1
over the two periods. There were no differences amongst treatment weight
gains (mean 94.3 kg) when a common pasture was grazed over summer.
In Trial 2 a new draft of weaner steers grazed the same speargrass paddocks
from May to August 1970 with the supplements balanced for energy content.
They, received Nil, 680 g cottonseed meal, 650 g sorghum meal, or 650
g sorghum meal + 113 g biuret. Cottonseed meal remained the most effective
supplement with 18.0 kg head-1 gain versus –16.5 kg
head-1 for no supplement. Sorghum meal plus biuret gave maintenance
(–1.4 kg head-1 and sorghum meal –10.0 kg head-1.