Growing lambs are frequently subject to varying planes of nutrition. Knowledge of the response of lambs to the restoration of non-limiting feeding conditions following a period of feed restriction is necessary in order to determine economic systems for finishing lambs.

Thirty Blackface wether lambs (birth weight 3.8 kg s.d. 0.38 kg) were treated in two ways from birth to 25 kg live weight (LW). One half were reared by well-fed ewes at grass (treatment UR). The other lambs sucked poorly-fed ewes up to weaning at 18.2 kg LW (s.d. 1.9); thereafter R lambs were given 700 g/day of a high quality pelleted feed (F) to 25 kg LW. Feed F contained 158 g crude protein/kg dry matter (DM) and had an estimated metabolisable energy yield of 12.5 MJ/kg DM.

From 25kg LW both UR and R lambs had ad libitum access to feed F to a final LW of 45 kg unless slaughtered earlier. The feed intakes and LW of individual sheep were measured weekly. Six lambs from each treatment were slaughtered at 25 kg LW in order to assess the effect of treatment on body composition. Three lambs from each treatment were subsequently slaughtered at 35 kg, 40 kg and 45 kg LW. Weights of gut-fill and organs were recorded and the cold carcass (CC) dissected into lean, bone and fat.