Effects of adding Bacillus coagulans to the diet on diarrhea, gut microbiota, and metabolites in yak.

Abstract

The role of Bacillus coagulans in enhancing animal growth performance and immune function is increasingly recognized. However, its effects on diarrhea, gut microbiota, and metabolites in yaks in China's high-altitude regions remain unclear. This study randomly divided 20 two-year-old male yaks of similar body weight into two groups of 10 animals each. One group served as the control group (CG) fed a basal diet, while the other group received the basal diet supplemented with 1&#xa0;g Bacillus coagulans per kg of base concentrate (live bacteria count&#x2009;&#x2265;&#x2009;5&#x2009;&#xd7;&#x2009;10&#x2079; CFU/kg) as the experimental group (CP) for 60 days. The Probiotic supplementation significantly reduced the incidence of diarrhea and diarrhea index in the CP group compared to the CG group (P&#x2009;<&#x2009;0.05), decreasing by 2.34% and 2.2, respectively. Additionally, CP group levels of IgA, IgM, IgG, IL-10, NOS, and T-Aoc were significantly elevated (p&#x2009;<&#x2009;0.05) relative to CG. Notably, Bacillus coagulans supplementation significantly increased beneficial gut bacteria (Phascolarctobacterium, Agathobacter, Roseburia) in the CP group while suppressing harmful bacteria (e.g., Clostridium). It also modulated metabolic pathways, promoting the production of anti-inflammatory metabolites such as 5-(4-Methoxybenzylidene)-1,3-thiazolidine-2,4-dione, (8'S)-Latochrome, and N-Lauroyl Tyrosine. Consequently, the CP group exhibited higher levels of short-chain fatty acids (SCFAs), including lactic acid, butyric acid, valeric acid, and propionic acid, compared to the CG group. Ultimately, this enhanced yak immune function and reduced diarrhea incidence. Overall, these results suggest Bacillus coagulans may serve as an effective alternative to antibiotic growth promoters for improving yak diarrhea and gut health.