Reducing age at first calving in N'Dama heifers using groundnut cake as a supplement to grazed natural pasture in The Gambia.

N'Dama heifers, initially weighing 129 kg at approximately 30 months of age, were supplemented with 250, 500 or 1000 g/head/day groundnut cake for 3 or 6 months during the dry or dry and wet seasons. Highly significant improvements in rates of liveweight gain and reproductive performance were obtained. Supplementation during the dry season only, approximately trebled the proportion of animals calving within 2 years of the beginning of the trial (6 vs 20%, P < 0.05), while this increase was around eight-fold in the animals that continued to receive supplement during the wet season (6 vs 50%, P < 0.05). Conceptions occurred at an overall mean liveweight of 185 kg, and a "target" liveweight of 200 kg for the first conception of N'Dama heifers is proposed as the basis for husbandry recommendations concerning these animals. It is concluded that such intervention can reduce the usually observed age at first calving of village based N'Dama heifers by 12 months, in a fashion that is both practicable and financially advantageous.