Body composition studies with the milk-fed lamb. III. The effect of the protein and energy intake on the composition of the live-weight gain

Abstract

SUMMARYNineteen male cross-bred lambs, aged between 2 and 5 days, were allotted to each of three dietary treatments. The protein contents of the diets (on a dry-matter basis) were 12·0% (diet A), 28·5% (diet B) and 45·5% (diet C). The energy intakes of groups of lambs within each dietary treatment varied from below maintenance to ad lib.The experimental period was of 3 weeks and the composition of the live-weight gain was estimated by the comparative slaughter method.Body composition within each dietary treatment was highly correlated with empty body weight, but not with the previous energy intake. The fat content of the gain decreased, and the water and protein contents increased, as the dietary-protein concentration increased.When compared at the same empty body weight, the protein content of the fat-free body of lambs given diet C was significantly higher than that of lambs given diet A. This effect of dietary-protein concentration could not be explained by differences in the amounts of protein stored as wool.