Three diets containing 0, 45 or 90 g fish meal dry matter (DM) per kg diet DM were given to lambs in sufficient quantities to provide energy for maintenance and 150 g daily gain. The lambs grew directly from 30 to 40 kg live weight (C) or were given a maintenance diet only such that they remained at 30 kg live weight for 12 weeks before being allowed to proceed to 40 kg (R). The 48 lambs were slaughtered at 40 kg. Preliminary slaughter groups provided data upon the fleece-free empty body weights for both C and R lambs at 30 kg live weight.
There were no significant diet × growth pattern interactions. R lambs ate more DM (P < 0·01) and had greater fleece-free empty body gains (P < 0·01) than C lambs. The inclusion of fish meal in the diet increased fleece and offal weights (P < 0·05) and fleece-free empty body gains (P < 0·01). Much of the response was confined to the first increment of fish meal. The preceding growth pattern had little effect upon the response of the lambs to dietary supplements of fish meal.