Effects of dry season supplementation of Calliandra calothyrsus leaf-meal mixed with maize-bran on dairy cattle milk productivity in the West Usambara Highlands, Tanzania

Abstract The dry seasons decline in milk production due to insufficient feed supply to dairy cattle poses a great challenge to sustainability of smallholder dairy production systems in Tanzania. Locally produced leguminous fodder tree leaf meals combined with maize bran provide a great potential for overcoming the dry season protein-energy deficit in the basal roughage feeds. This study evaluated the effects of dry season Calliandra calothyrsus (Calliandra) leaf-meal: maize-bran based protein-energy homemade supplementary ration (HSR) on milk production of lactating cross-bred dairy cows in the Western Usambara Highlands (WUHs), Tanzania. Complete randomized design was employed whereby four groups of 4 lactating dairy cows were subjected to four levels of HSR rationed at 0, 2, 4 and 6 kg/cow/day. The lactating cows which were not subjected to HSR supplementation (0 kg/cow/day) were left under farmers’ feeding practices as a control. HSR had significant effect on dry season milk yields (P < 0.001) whereby milk yields were 2.7, 4.5, 5.6 and 6.1 litres/cow/day for 0, 2, 4 and 6 kg HSR/cow/day, respectively. In addition, simulated year-round daily milk yields indicated that 4 and 6 kg HSR/cow/day would double the milk yields. Nevertheless, there was overall significant difference in the income to cost ratios (P = 0.02) whereby it was 0.50, 0.79, 1.06 and 1.09 for 0, 2, 4 and 6 kg HSR/cow/day, respectively. However, the income to cost ratios for 4 and 6 kg HSR/cow/day did not differ significantly (P < 0.05). In conclusion, if the dairy farmers in WUHs are to produce profitable milk amounts during the dry seasons the supplementation level of 4 kg HSR/cow/day to the basal diets is recommended.