THE EFFECTS OF SUPPLEMENTARY CHINESE MILK VETCH SILAGE ON THE GROWTH-RATE OF CATTLE AND THEIR INTAKE OF AMMONIATED RICE STRAW

Thirty-two Holstein heifers were allocated to four groups and used to investigate the response in growth rate to supplementing ammonia bicar bonate-treated rice straw (ABRS) with Chinese milk vetch( Astragalus s inicus L.) silage (MVS). All groups were offered ABRS ad libitum with 1 kg of a concentrate mixture per head per day, and the MVS was supple mented at levels of 0, 10, 20 or 30% of the calculated dietary dry mat ter intake. Intake of ABRS was not affected by a 10% inclusion rate of MVS but inclusion at each of the higher levels reduced ABRS intake, D ry matter intakes were higher in all three supplemented groups, and da ily liveweight gains were 588 g, 692 g, 800 g and 777 g in the groups supplemented with MVS at levels of 0%, 10%, 20% and 30%, respectively. When MVS accounted for 20 or 30% of the diet, the liveweight gains we re significantly higher than in the non-MVS group (P<0.05). Concentrat e consumption per kilogram liveweight gain was 1.70 kg, 1.45 kg, 1.25 kg and 1.30 kg for the 0%, 10%, 20% and 30% levels, respectively. It i s concluded that supplementation of an ABRS-based diet with MVS may im prove the growth rate of ruminants and save concentrate consumption. T he results of orthogonal contrasts indicate that the optimal level of supplementary MVS in this study was 23% of the dietary dry matter inta ke. (C) 1997 Elsevier Science B.V.