Two trials were carried out to examine the effects of crude protein level in rations for intensively-finished suckled bulls. In 1987/88 (Year 1) high levels were tested as a possible means of delaying finishing and in 1988/89 (Year 2) low levels were tested.

In both years 54 Charolais x (Hereford x Friesian) bulls born in May-June were weaned in November, following paddock-grazing of cows and calves on permanent grassland. Following weaning, the bulls were housed in straw-bedded yards and offered wilted grass silage, with concentrate feed gradually increased. After 14 days the silage was removed and concentrates offered ad libitum. The bulls were allocated to 1 of 3 treatments with 2 replicates per treatment to provide 6 groups of 9 bulls. The experimental diets consisted of rolled barley with a pelleted protein concentrate and extra mineral supplement when appropriate, as described in Table 1. This resulted in diets with a range of protein but similar major mineral contents.