Yeast Culture Improves Intestinal Barrier Function and Growth Performance in Yaks by Modulating Gut Microbiota and Microbial-Derived Metabolites.

This study investigated the effects of yeast culture supplementation on intestinal health and growth performance in male yaks. A total of four dietary treatments were established, including a basal diet (CON) and diets supplemented with 0.1, 0.5, and 1.0 g/kg yeast culture (CEL1, CEL2, and CEL3, respectively). Results showed that yaks in the CEL2 group exhibited significantly increased average daily gain compared with the control group (P < 0.05). In addition, serum antioxidant enzyme activity was partially improved, as evidenced by increased glutathione peroxidase activity, accompanied by a significant reduction in tumor necrosis factor-α levels (P < 0.05), indicating modulation of immune-related responses. Histological analysis revealed that yeast culture supplementation reduced jejunal crypt depth and increased the villus height to crypt depth ratio and PAS-positive material area, with significant effects observed in the CEL1 and CEL2 groups (P < 0.05). Moreover, the expression and distribution of the tight junction protein ZO-1 in the jejunum were significantly altered in the CEL2 group (P < 0.05), suggesting changes in intestinal epithelial structure. Microbiome analysis revealed differences in gut microbial composition between the CON and CEL2 groups, accompanied by alterations in intestinal metabolite profiles involving amino acid, lipid, and energy metabolism-related pathways. Integrated analysis indicated that yeast culture supplementation was associated with improved growth performance and changes in gut microbiota and metabolic profiles. Compared with the control group, supplementation with 0.5 g/kg yeast culture was associated with beneficial responses in several measured parameters under the conditions of this study.