The effect of three different growth rates on feed utilization of cattle

Abstract

This paper describes the effect of three different growth rates from 300 to 440 kg liveweight on feed utilization of Angus steers. The growth rates studied were high (H, 0.8 kg/d), low (L, 0.4 kg/d) and high-maintenance (HM, 0.8 kg/d, followed by a period during which liveweight was held constant). Animals were offered a variable amount of a pelleted concentrate ration, together with a fixed amount (0.9 kg) of oaten straw daily. The DM intakes of both dietary components were related to a number of different indices of animal performance. Differences between treatments were found in DM intake per unit liveweight gain (H < L < HM), empty body weight gain (H < L, HM) and carcass weight gain (H < L, HM). DM utilization was similar in the three treatments, however, when carcass gains were corrected to a common level (18 %) of dissectible fat in the carcass. Carcass energy gains were calculated from the results of chemical analyses and related to DM intake. DM was converted to carcass energy more efficiently in the H than in either the L or HM treatments. An analysis of dietary protein utilization showed that the efficiency of carcass protein storage in the three treatments was similar.