Responses to nitrogen and maize supplements by young cattle offered a low-quality pasture hay
1987
Lee, G.J. | Hennessy, D.W. (New South Wales Dept. of Agriculture, Grafton (Australia). Agricultural Research Station) | Nolan, J.V. | Leng, R.A. (New England Univ., Armidale (Australia). Dept. of Biochemistry Microbiology and Nutrition)
Both urea and protein meal supplements increased intakes of hay and total digestible organic matter (DOMI), but there was a significant interaction between maize and N supplements such that maize increased hay and DOM intakes when offered alone. The intakes of hay by the urea and protein meal supplemented groups were not significantly different. Both N and maize supplements had positive effects on liveweight change, with N having the largest effect. Steers supplemented with protein meal gained more than those offered urea, indicating an effect of protein on the efficiency of utilisation of absorbed nutrients. N supplements increased rumen ammonia concentrations. Total volatile fatty acid concentrations in the rumen did not differ significantly between supplements. Glucose entry rate was positively related to liveweight change and was increased by both the N supplements and whole maize. Glucose entry rate, adjusted for DOMI, was higher in protein meal supplemented steers than those receiving urea or no N supplement, and these steers had the highest growth rate. Urea pool size, and synthesis rate in the body, were greater in steers given the urea and protein meal supplements.
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