The effect of supplementing silage-based diets with soya bean and fish meals for finishing beef cattle

Abstract

ABSTRACTTwo experiments have been carried out to examine the effects on the intake and performance of finishing beef cattle of supplementing grass silages (perennial ryegrass) of medium and high digestibility (MD and HD respectively) with either extracted soya-bean meal or fish meal. In each experiment, the two silages were supplemented with (1) barley (107 g crude protein (CP) per kg dry matter (DM)), (2) a mixture of barley and soya-bean meal (187 g CP per kg DM) and (3) a mixture of barley and fish meal (182 g CP per kg DM) in a 2 × 3 factorial design. The MD silages were supplemented with 4·5 kg concentrates per head daily in each experiment and the HD silages with 2·75 and 2·5 kg per head daily in experiments 1 and 2 respectively. In experiments 1 and 2 respectively the diets were offered to 72 and 60 castrated male cattle of late maturing breed type which were initially 455 (s.e. 3·6) and 484 (s.e. 3·2) kg live weight; the MD silages contained 642 and 652 g digestible organic matter (DOM) per kg DM, 119 and 114 g CP per kg DM, 72 and 68 g NH3N per kg total N, and the HD silages contained 698 and 724 g DOM per kg DM, 158 and 148 g CP per kg DM, 58 and 51 g NH3N per kg DM. In experiment 1 for the MD silages supplemented with concentrates 1, 2 and 3 and the HD silages supplemented with concentrates 1, 2 and 3 respectively silage DM intakes were 5·47, 5·29, 5·24, 6·86, 6·77 and 6·76 (s.e. 0·129) kg/day; carcass gains 0·76, 0·74, 0·72, 0·75, 0·75 and 0·79 (s.e. 0·011) kg/day; subcutaneous fat depths 6·8, 7·8, 8·0, 9·2, 7·2 and 7·1 (s.e. 0·59) mm and areas of m. longissimus 21·5, 21·7, 23·2, 21·5, 22·4 and 21·9 (s.e. 0·78) mm2/kg carcass weight. Corresponding values for experiment 2 were 6·12, 6·05, 6·18, 7·65, 7·53 and 7·36 (s.e. 0·235) kg/day; 0·82, 0·88, 0·83, 0·85, 0·89 and 0·83 (s.e. 0·042) kg/day; 8·1, 7·8, 7·5, 9·1, 8·3 and 7·4 (s.e. 0·77) mm; 22·8, 21·9, 21·9, 21·0, 21·9 and 21·7 (s.e. 0·79) mm2/kg carcass weight. It is concluded that supplementation of MD or HD grass silages with soya-bean or fish meals did not significantly affect the intake, performance or carcass fatness of finishing beef cattle although the carcasses of animals offered HD silage supplemented with barley tended to be fatter than those from the other treatments.