Food additives are used to increase growth rate by young growing cattle in their first winter before being turned out to graze. Evidence indicates that increased gains may not be retained through the grazing season. A trial was made to measure the effect of food additives on the performance of young growing cattle during winter and subsequently through the grazing season. Sixty British Friesian castrated male calves were offered grass silage ad libitum (DM 198g/kg; ME l0.0MJ/kg DM; CP 130g/kg DM) supplemented with either bruised barley or dried, molassed sugar beet pulp.