EFFICIENCY OF NITROGEN-UTILIZATION BY PREGNANT WEST AFRICAN DWARF GOATS FED VARIOUS LEVELS OF CRUDE PROTEIN IN THE DIET

Twenty pregnant West African dwarf (Fouta djallon) goats, with mean live weights of 26.3 ± 0.6 kg, were used in a crude protein (CP) utilization study to ascertain optimal dietary levels. Does were randomized into five groups of four animals each. Five supplements with 5, 10, 15, 20 and 25% CP were prepared from cassava flour, dried brewer's grain, molasses and urea. Each animal group was fed one of the protein supplements to basal grass (Cynodon nlemfluensis) hay. Nitrogen intake (NI), apparently absorbed nitrogen (AAN), faecal nitrogen (FN), urinary nitrogen (UN) and retained nitrogen (RN) increased significantly (P<0.05) with increasing CP in the diets. Over 70% of daily dry matter (DM) intake was from concentrate supplements. Changes in the rate of NI and AAN with increasing CP in the supplement were described by exponential equations which showed that the initial rate of change was 0.097, which declined at 0.012 per unit increase of CP in the concentrate. Corresponding values of 0.116 and 0.017 were obtained for AAN. Both NI and AAN increased exponentially (P<0.01) with increasing CP in the supplement. By differentiating regression equations of NI and AAN, peak rate of change per unit change of CP in the concentrate occurred at 20 and 17% CP, respectively. Results showed that it would be uneconomical to go beyond 20% CP in the concentrate as supplement for pregnant West African dwarf goats. © 1990.