Change in metabolite levels and liveweight of grazing cattle when supplemented with Leucaena leucocephala or urea-molasses
1987
Foster, A.H. (Queensland Dept. of Primary Industries, Gayndah (Australia). Brian Pastures Pasture Research Station) | Blight, G.W. (Queensland Dept. of Primary Industries, Rockhampton (Australia). Biometry Branch)
Liveweight change and the concentration of a number of metabolites in rumen fluid, blood and faeces were monitored in cattle from weaning until they were 33 months old, grazing spear grass alone and when supplemented with either Leucaena leucocephala, urea molasses, or both. Levels of metabolites in unsupplemented cattle in winter reflected the poor protein content of spear grass. A low molar percentage of higher volatile fatty acids in rumen fluid indicated a shortage of amino acids in the feed; and the low ammonia nitrogen concentrations would have limited bacterial protein production. A true dietary protein supplement (leucaena) significantly increased the molar percentage of higher volatile fatty acids in the winter and spring, which urea-molasses did not. Both supplements increased rumen concentrations of ammonia nitrogen in winter, but only leucaena increased concentrations in spring in both yearlings and two-year-olds supplemented with urea-molasses lost weight. In spring, yearlings and two-year-olds supplemented with leucaena gained weight, but liveweight gain from urea-molasses supplement was not significantly different from that of unsupplemented cattle. The better gains from leucaena seem due to leucaena's superior amino acid profile.
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