THE EFFECT OF SUPPLEMENTATION WITH LEUCAENA-LEUCOCEPHALA AND MAIZE BRAN ON VOLUNTARY FOOD-INTAKE, DIGESTIBILITY, LIVE WEIGHT AND MILK-YIELDOF BOS-INDICUS X BOS-TAURUS DAIRY-COWS AND RUMEN FERMENTATION IN STEERS OFFERED PENNISETUM-PURPUREUM AD-LIBITUM IN THE SEMI-HUMID TROPICS

An experiment was carried out to evaluate dairy performance and rumen fermentation from a forage-based diet supplemented with Lucaena leococ ephala (leucaena) and maize bran. Bos indicus (Ayrshire/Brown Swiss) X Bos taurus (Sahiwal) cattle were offered Pennisetum purpureum (napier grass) ad libitum either unsupplemented (N) ol supplemented on a dry- matter (DM) basis with I kg (LL) or 2 kg leucaena (LH) or 2 kg leucaen a together with I kg DM maize bran (LHM). Food intake, milk yield, die t apparent digestibility and nitrogen balance were measured using eigh t cows (mean live weight 384 (s.d. 41) kg in two 4 X 4 Latin squares. Rumen fermentation was measured using four rumen fistulated steers (me an live weight 352 (s.d. 12) kg in a 4 X 4 Latin square. Performance w as recorded during the last 7 days of each 21-day experimental period. Supplementation increased food intake (6.3, 7.6, 7.9 and 8.7 kg DM pe t day; P < 0.01; s.e.d. 0.24) end milk yield (5.1, 5.4, 5.5 and 6.5 kg /day; P < 0.01; s.e.d. 0.28)for N, LL, LH and LHM respectively. Supple mented diets tended to be mole digestible compared with napier grass a s the sole food (organic matter apparent digestibility coefficients 0. 54, 0.55, 0.57 and 0.57; s.e.d. 0.020; N, LL, LH and LHM, respectively ) and N balance increased progressively with supplementation. Suppleme ntation progressively increased rumen ammonia-nitrogen concentrations in steers and the rate of rumen degradation of napier grass increased when leucaena (diets LL and LH) teas offered. The results suggest that supplementation of napier grass with leucaena increased DM intake owi ng to increased ammonia concentrations and rates of napier degradation in the rumen. Supplementation of the forage diet with I kg DM maize b l an did not significantly reduce the rumen degradation of napier gras s and increased the molar proportions of propionate which may have inc reased the efficiency of utilization of metabolizable energy and there fore milk production.