A comparison of pasture grazing and storage feeding, and the effects of sward surface height and concentrate supplementation from 5 to 10 months of age on the lifetime performance and carcass composition of bulls

Abstract

A 3-year experiment was carried out to compare systems of bull beef production involving continuous housing or pasture grazing from 5 to 10 months of age and to examine the effects of herbage allowance and concentrate supplementation on lifetime performance and carcass quality. Animals were either set-stocked at pasture to maintain nominal sward heights of 7, 9 and 11 cm or were offered grass silage (700 g digestible organic matter per kg dry matter (DM)) supplemented with 1·5 and 3·0 kg barley-based concentrates (183 g crude protein per kg DM) per head daily. Half of the animals grazed at each sward height were given 1·5 kg concentrates per head daily while the remainder received no supplement. A total of 160 continental X Friesian and 48 Friesian calves which were initially 197 kg live weight were used. From 10 months of age until slaughter at about 17 months all animals were given grass silage ad libitum and supplemented with 3·0 (year 1) or 3·75 (years 2 and 3) kg cereal-based concentrates per head daily.Animals which grazed the 9- and 11-cm swards produced carcasses of similar weight to those given silage and 3·0 kg concentrates per day, while those grazing the 6·7-cm swards produced carcasses of similar weight to those given silage supplemented with 1·5 kg concentrates. Reducing sward surface height from 11·0 to 9·3 cm did not affect performance but further reductions to 7·9 (year 1) and 6·7 (years 2 and 3) cm reduced live-weight gain by 0·13 and 0·32 kg/day respectively. Concentrate supplementation did not affect the performance of animals grazing swards which were 7·9 cm or taller but increased live-weight gain by 93 and 193 g/kg concentrates for those grazing the 6·7 cm swards and those receiving silage respectively. Differences in live weight at 10 months of age due to the feeding treatments imposed from 5 to 10 months of age were largely retained until slaughter at 17 months as there was little compensatory growth during the residual period. The treatments did not affect carcass composition when the data were adjusted to a constant carcass weight, or meat quality which was satisfactory for all treatments.