Published online by Cambridge University Press: 02 September 2010
1. Groups of 12 male and 12 female lambs, early weaned and individually fed, were used at six centres in Great Britain to determine the effect of dietary protein concentration on growth rate and feed utilization from weaning to 37 kg live weight. Three diets varying in the proportion of rolled barley to white-fish meal were used to give 13·5, 16·0 or 18·5% crude protein in the dry matter. The diets were pelleted and offered ad libitum.
2. The male lambs showed significantly poorer growth rates and feed conversions on the low-protein than on the other diets. Results for the females were more variable so that although the mean values showed similar trends these were not statistically significant.
3. Female lambs had about 19% lower growth rates than male lambs. The mean food conversion (kg dry matter/kg gain) with the diet containing 16% crude protein was 2·67 for the males and 3·30 for the female lambs. Food utilization differed significantly between centres, the centres using lambs of Finn Dorset breeding having lower growth rates and poorer food utilization than Suffolk crosses.