Effect of Yeast Culture on Growth of Beef Cattle Fed on Grass Silage plus Barley Based Concentrates
The effects of dietary inclusion of yeast culture (Yea Sacc; Saccharomyces cerevisiae plus growth medium; 5 X 106 organisms/g) on growth, feed conversion efficiency and carcass traits of beef cattle were examined in three experiments. The animals were con tinental breed crosses and in each experiment were offered grass silage ad libitum. In Experiment 1, young bulls (14 per treatment, initial liveweight (LW) 315 kg) were offered either no additive or 10 g yeast culture per animal daily for 203 days plus an average of 3.8 kg per animal daily of supplementary concentrate dry matter (DM) In Experiment 2, young bulls (20 per treatment, initial LW 310 kg) were offered either no additive or 15 g yeast culture per animal daily for 220 days plus an average of 3.5 kg per animal daily of supplementary concentrate DM. In Experiment 3, growing heifers (20 per treatment, initial LW 271 kg) were offered either no additive or 15 g yeast cul ture per animal daily for 127 days plus an average of 0.86 kg concentrate DM per ani mal daily. In Experiment 1, yeast culture had no effect on feed intake or slaughter traits but did increase (P<0.05) average daily gain (1.18 v. 1.11 kg/day) and tended (P<0.1) to improve the conversion of dietary DM to liveweight gain (6.92 v. 6.57 kg DM intake/kg liveweight gain) In Experiment 2, neither feed intake, liveweight gain, feed conversion ratio nor any measured slaughter trait was influenced by yeast culture. In Experiment 3, neither DM intake, liveweight gain nor feed conversion ratio was influenced by yeast culture. It is concluded that dietary inclusion of yeast culture resulted in only a marginal improvement in growth and efficiency of cattle fed a basal diet of grass silage and barley based concentrates.