Nitrogen utilization and microbial protein synthesis
In buffaloes the effects of ELM supplementation in concentrate with rice straw as roughage on nitrogen metabolism and efficiency of microbial protein synthesis are summarized in Table 5. The results revealed that supplementation of ELM did not affect nitrogen utilization. In this study, it was observed that positive nitrogen retention and absorption were obtained in the ELM supplemented group and were not different among treatments. Similarly, Benchaar et al. (2006) observed no change in N retention when cows were fed with 2 g/d of the Crina ruminant supplement. According to Cutrignelli et al. (2007), PD excretion ranged between 28 and 34 mmml/d and was not affected by treatments. Moreover, no PD parameter was impacted by EML feeding; therefore calculated microbial protein synthesis yield also was not different among treatments which were similar to the results of Newbold et al. (2004) who reported no change in bacterial N flow, estimated from excretion of urinary PD, when sheep were supplemented daily with 100 mg of mixed EO. Under this study, ELM supplementation tended to improve the N retention and efficiency of microbial N synthesis.