This study was conducted to investigate the impact of dietary inclusion of Moringa oleifera leaf meal
(MLM) as a substitution for soybean meal on nutrient digestibility, rumen fermentation, rumen enzyme
activity, blood metabolites, growth-related hormones, and growth performance of buffalo calves. Thirty
buffalo calves eight to nine months of age with an average body weight of approximately 153.7 ± 0.97 kg
were randomly distributed through three dietary treatments (ten calves/treatment). MLM inclusion rates
were 15% (M15) and 20% (M20), replacing soybean meal by 50 and 75% in the concentrate mixture,
respectively. The results indicated that, digestibility of dry matter, organic matter (OM), and crude fiber
(CF) increased significantly (p < 0.05) with MLM inclusion, while the digestibility of crude protein (CP)
and ether extract (EE) reduced significantly (p < 0.05) with MLM addition. Dietary supplementation with
MLM significantly affected (p < 0.001) rumen fermentation by reducing ruminal enzymes, ruminal
ammonia-N, total protozoa, and acetate/propionate ratio and increasing acetic, propionic, and butyric
acids and total volatile fatty acid concentrations (p < 0.001). Furthermore, dietary inclusion of 15%
MLM significantly improved (p < 0.001) final body weight, dry matter intake of feed, daily weight gain,
feed conversion efficiency, blood metabolites, and plasma insulin growth factor-I (IGF-I). It can be concluded
that MLM is a multi-purpose protein supplement that provides some nutritional and therapeutic
advantages when replacing 50% of soybean meal. Dietary supplementation of 15% MLM improved rumen
fermentation, growth performance, blood metabolites, plasma IGF-I and mitigated ammonia and
methane without any adverse effects in growing buffalo calves.