Leucaena leucocephala leaf meal as supplement to diet of grazing dairy cattle in semiarid Western Tanzania

The effect of supplementation with three levels of Leucaena leucocephala leaf meal (LLM) added to a diet composed of cotton seed hulls (CSH) and maize bran (MB) on milk yield, milk composition and body weight changes of grazing lactating cows was studied in a completely randomised design. Marginal product analysis for the different levels of LLM as a substitute to cotton seed cake (CSC) was also calculated. The following treatment diets were used in the experiment: Diet 1, (control) composed of 1.8 kg DM CSH and 1.8 kg DM MB. Diet 2, 3 and 4 had an addition of 1.2, 2.0 and 2.6 kg DM of LLM respectively. Diet 5 was composed of 1.8 kg DM of CSC and 1.8 kg DM of MB. Treatments, number of lactations, farm and initial milk yields significantly (P < 0.01) influenced milk production. LLM supplementation to grazing cows significantly increased milk production, weight gain and milk composition (P > 0.05). Cows on treatment 1 achieved no significant (P < 0.05) increase in milk yield compared to cows on treatment 2, 3, 4 and 5 which attained net milk increase of 3.6, 4.1, 6.7 and 4.4 litres/cow/day respectively. There was no significant (P > 0.05) difference in net milk produced by cows on treatment 2, 3 and 5 compared to treatment 1. LLM supplementation significantly (P < 0.05) increased total solids (TS) in milk compared to that of cows under control, but there was no significant (P > 0.05) influence on milk crude protein (CP), butter fat (BF), solids not fat (SNF) and ash in all the diets. Body weight was significantly (P < 0.05) increased by LLM supplementation. Degradation coefficients of the treatment diets were high and varied significantly (P < 0.01) and had an influence on the metabolizable energy value of the treatment diets. Cows on diet 2 to 4 had a weight gain of 190.9, 101.8 and 80.9 g/cow/day respectively and cows on diet 5 attained the highest weight gain (234.5 g/cow/day). Diet 4 had the highest marginal productivity of 4.3 followed by diets 2, 3 and 1 with marginal productivities of 2.8, 0.6 and 0 respectively. It was therefore, concluded that the optimal supplementation level using LLM as a substitute for the more expensive CSC was diet 4.This revised version was published online in November 2005 with corrections to the Cover Date.