1. Broiler chickens were fed 60-100% of recommended energy intakes to study the effects of energy restriction on protein and fat retention. 2. At an energy retention of 179 kJ/kg W0.75 d, only protein was retained. At higher energy intakes, each increment in retention had a rather constant composition: about 85% energy in fat and 15% in protein. At lower energy intakes body fat was mobilised whereas protein was deposited. 3. The efficiencies of energy retention in protein and fat were estimated to be 0.66 and 0.86 respectively. 4. The rather constant composition of additional retained energy after additional energy supply provides an explanation for a linear relationship between energy intake and energy retention.

The potential for increased productivity of N'Dama cattle in response to small supplementary inputs of proteinaceous by-products has been shown to be substantial under village husbandry conditions in The Gambia. Young N'Dama bulls were used to compare sesame cake with cottonseed as sources of supplementary protein during the wet and early dry seasons of 1987. They were fed 0, 40, 80 or 160 g crude protein/day in these forms for four months. Supplementation significantly increased growth rate from 169 g/d in controls to means of 272 and 271 g/d for those given sesame cake and cottonseed respectively; there were no significant differences among the supplemented groups. During the four months of the dry season immediately after supplementation ceased all previously supplemented groups grew significantly more rapidly than the controls (at least P less than 0.05), indicating a substantial carry over effect of the supplements. Over this period the mean gain of the groups previously given sesame cake exceeded that of those that had received cottonseed (217 cf. 158 g/d; P less than 0.01). The economic benefits of these responses were substantial.