Scarce and poor-quality food resources limit smallholder dairy production in the tropics. Food resources for zerograzing may be improved by intercropping Pennisetum purpureum (napier grass) with Leucaena leucocephala leguminous hedgerows. To evaluate dairy cow performance from this alley cropping system, 36 Ayrshire/Brown Swiss × Sahiwal cows in a 2×3 factorial design were individually fed from the 3rd week of lactation for 14 weeks on diets of napier fodder harvested at 1·0 m or 1·5 m and offered ad libitum, supplemented with 0, 4 or 8 kg fresh weight leucaena fodder. Average daily milk yield during the 2nd week of lactation was a covariate in the analyses of milk yield, and post-partum live weight a covariate in the analyses of dry matter (DM) intake and live-weight change.
Napier harvesting height and leucaena level had independent effects on performance. Napier height (1·0 m or 1·5 m) significantly (P < 0·01) affected daily napier DM intake (9·3 and 6·8 kg), total daily DM intake (10·5 and 7·9 kg), daily live-weight losses (165 and 490 g) and daily milk yield (8·6 and 6·9 kg respectively). Leucaena supplementation (0, 4 or 8 kg) significantly (P<0·01) increased total daily DM intake (7·8, 9·3 and 10·4 kg), reduced daily live-weight loss (560,235 and 175 g), and increased daily milk yield (7·3, 7·7 and 8·3 kg respectively). The results show that reasonable dairy performance can be achieved in the tropics by supplementing a napier fodder basal diet with leucaena forage, and highlight the importance of the stage of harvesting of the napier fodder. The results are discussed in relation to the nutrient requirements for milk production given by the Agricultural Research Council (1980 and 1984).