A randomised block experiment, involving 126 British Friesian and Friesian cross beef male calves which were initially 46.7 kg and 10 days old, has been carried out to examine the effects of the quantity of milk substitute consumed per calf on the lifetime performance of calves reared for beef production. The three treatments were (1) 400 g milk powder per head daily, weaned at 6 weeks old (2) ad libitum intake of milk powder, weaned at 6 weeks (3) ad libitum intake of milk powder, weaned at 8.5 weeks. Calves on treatment 1 were bucket fed twice daily, while those on treatments 2 and 3 suckled the milk from teats. The calves were purchased in three groups in (1) October, 1983 (2) December, 1983 and (3) February, 1984. Three commercial brands of acidified milk substitute were used, one for each group. All animals were individually penned until after weaning. They were offered a pelleted concentrate, based on barley and soyabean meal, ad libitum from two weeks old until intake reached a maximum of 2.7 kg per head daily. Hay was offered ad libitum to six weeks of age and well preserved grass silage was offered ad libitum thereafter. Group 1 calves were on an 18 month grass/cereal beef system, group 2 on a 22 month grass system and group 3 on a 15 month silage/ cereal system. The chemical compositions of the milk substitutes, concentrate and silage are given in Table 1.