Influence of concentrate level during winter and date of turnout to pasture on the performance of cattle and the effect of grazing of silage ground on grass yield and quality

The effects of two concentrate levels ((0.5 (low) and 1.5 (high) kg/day)) w ith ad libitum grass silage in winter and two turnout dates (21 March and 1 1 April) on the performance of 8-month-old spring-born continental-cross we anlings were examined. Animals on the earlier turnout treatment grazed the designated silage area until 11 April after which all animals grazed togeth er. Sixty-eight animals (40 steers and 28 heifers) with average initial liv e weights (29 November) of 333 (s.e. 6.3) and 306 (s.e. 4.6) kg, respective ly, were used. Silage intakes were 4.7 and 4.4 (s.e. 0.16) kg dry matter pe r head per day for the low and high concentrate levels, respectively. Mean winter live-weight gains were 69 and 89 (s.e. 3.6) kg for those on the low and high concentrate levels, respectively. Corresponding summer gains were 193 and 177 (s.e. 4.4) kg. Combined winter plus summer live-weight gains we re 271 and 257 (s.e. 4.5) kg for the early and late turnout treatments, res pectively (P < 0.05). There were no treatment effects on carcass weight or carcass traits of heifers (slaughtered at the end of the grazing season in November) or steers (housed on 24 October 1997 and slaughtered on 12 March 1998 following a winter finishing period on a silage-plus-concentrate diet) . Grazing the designated silage area reduced (P < 0.01) grass yield in earl y cut (14 to 20 May) silage plots but had no significant effect on those cu t later (3 to 6 June). It is concluded that feeding concentrates to achieve live-weight gains in excess of 0.55 kg/day in winter, while increasing win ter gain, did not result in higher slaughter or carcass weight. Earlier tur nout resulted in increased live-weight gain to the end of the grazing seaso n but had no effect on carcass weight.