The objective of this study was to investigate the effect of tropical legume (Phaseolus calcaratus) mixed with ruzi grass feeding on the performance of lactating dairy cows. Eighty-eight lactating dairy cows from 22 smallholder dairy farms northeast of Thailand were assigned to respective dietary treatments according to a Randomized Completely Block Design (RCBD). Four cows were selected from each farm and were allocated into two different feeding groups as follows: ruzi grass and P. calcaratus mixed with ruzi grass (1:1 ratio), respectively. All cows were fed with roughage ad libitum with 1:2 ratio of concentrate diet to milk yield. The results revealed that total dry matter intake, ruminal volatile fatty acids, and ammonia nitrogen concentration were enhanced when cows were fed with P. calcaratus mixed with ruzi grass (P < 0.05). Moreover, feeding tropical legume mixed with ruzi grass could increase milk production and milk protein in this study. Importantly, an economical assessment showed that milk income and the profit from milk sale were significantly greater in cows fed the mixture of roughage than those from the non-mixed group. This study concluded that high-quality roughage as tropical legume mixed with ruzi grass at the ratio of 1:1 brought out the remarkable and practical implementation for smallholder dairy farms, and the intervention was practical and deserving of more on-farm intervention.
Keywords: Dairy crossbreeds; High-quality roughage; Milk production; Phaseolus calcaratus; Smallholder dairy farms.