Nitrogen metabolism in indigenous Malawi goats

SUMMARY Four mature castrate Malawi goats, mean live weight 29·66 kg, were offered diets of poor quality Rhodes grass hay, or hay plus a concentrate comprising either maize bran or maize bran-cotton seed cake mixed in varying proportions, so that N intake varied from 4·76 to 20·81 g/day in a series of four metabolism trials. By extrapolation metabolic faecal N loss was estimated to be 9·94 g/kg faecal D.M. and that of endogenous urinary N to be 0·121 g/kg W 0·75 . The daily maintenance requirement for nitrogen was shown by a factorial method to be 0·682 gN/kg W 0·75 , and by use of regression equations to be 0·688 g N/kg W 0·75 or 0·314 g apparent digestible N/kg W 0·75 . The mean daily requirement was 8·8 g N, with a mean apparent digestibility of N of 43·4%, and a true digestibility of 80·0%.