AN ASSESSMENT OF THE BIOLOGICAL AND ECONOMIC-EFFICIENCY IN CONVERSIONOF MILK TO GROWTH IN NDAMA CALVES

Two groups of eight N'Dama calves were fed different quantities of mil k from birth to 10 months of age to compare efficiencies of converting milk to live-weight gain, and to assess the economic efficiencies of the two feeding regimes. Group 1 received an average of 347 (s.e. 2.4) kg per calf, with a daily and seasonal pattern of feeding designed to simulate a village production system where calves have access to only part of the milk produced by their dams, the rest being extracted for human consumption. Group 2 received an average of 617 (s.e. 5.1) kg p er calf, and simulated situations where no milk is extracted such as i n a ranch or station-type of operation. During the first 6 months, whe n growth was certainly mediated only by milk, and live-weight gains we re consistently positive at 151 and 262 g/day in groups 1 and 2 respec tively, the biological conversion of milk to live weight did not diffe r between groups (8.7 v. 8.8 kg milk per kg live-weight gain). When th e two groups were compared over the same weight range to remove possib le effects of variable maintenance requirements, the conversion effici encies again did not differ significantly. Over the whole 10-month per iod the biological conversion factors were slightly less favourable bu t still not different between groups (9.5 v. 9.4 kg/kg). When monetary values of milk and live weight at farmgate prices were applied to qua ntities of milk consumed and calf live-weight increases, the cost effi ciency of group 1 was superior to that of group 2. Based on these find ings and results from other on-farm experiments in The Gambia, it was concluded that the current practice of partial milk extraction as occu rs in the village production system is a logical approach for profit m aximization.