Exploring the effects of resveratrol and β-hydroxy-β-methylbutyric acid under different protein levels on the ileal health of tibetan sheep

Overall, when the dietary protein content was 14%, digestive enzyme activities, immune responses, and SCFAs levels in the ileum were improved, and the mucosal morphology of the ileum was enhanced. When the 14% protein diet was supplemented with RES and HMB, the concentration of butyric acid was increased. This increase was due to the regulation of the ileum microbiota (Firmicutes and <i>Clostridium_sensu_stricto_1</i>) and metabolites (xanthine and uric acid), which promoted the activities of digestive enzymes and immune responses and improved mucosal morphology in the ileum.