A comparative study of gut microbiota and metabolites in Tibetan sheep during cold and warm seasons

< 0.05), with KEGG enrichment linking these to steroid hormone biosynthesis, fatty acid metabolism, bile acid synthesis, and propanoate pathways. These findings suggest possible associations between seasonal extremes and: (1) modulation of nutrient metabolism (e.g., secondary bile acids and short-chain fatty acids); (2) activation of stress-response pathways (e.g., pentose phosphate pathway, ABC transporters, and DNA replication); and (3) immune regulation mediated by bioactive metabolites. Cold-season enrichment in DNA repair and energy-production pathways may be associated with responses to oxidative stress, whereas warm-season shifts in lipid metabolism are consistent with increased nutrient availability. Fluctuations in key metabolites-such as elevated melatonin in cold seasons and elevated ursolic acid in warm seasons-likely reflect adaptations related to thermoregulation and antioxidant defense. This work provides foundational insights into microbiota-host interactions under extreme environmental conditions, supporting the optimization of supplementation, probiotic use, and sustainable husbandry on the Qinghai-Tibet Plateau.