Abstract: The genetic characteristics of different pig breeds interact with the segmented intestinal environment to jointly drive the differentiation of bile acid metabolism-related microbial communities in the porcine intestine. To investigate variations in bile acid metabolism-associated gut microbiota across different intestinal segments among regional pig breeds, this study collected samples from the duodenum, jejunum, ileum, cecum, and colon of Dahe pigs, Dahe black pigs, and Changdu Tibetan pigs, respectively. High-throughput 16S rRNA sequencing was employed to analyze the composition of bile acid metabolism-associated bacterial communities and their species interactions. The results demonstrated that differences in intestinal segmental physicochemical environments lead to functional specialization of bile acid metabolism microbiota: the small intestine predominantly harbors Lactobacillus species with bile salt hydrolytic activity, which dominate primary bile acid hydrolysis; the cecum and colon were enriched with anaerobic bacteria such as Bacteroides, Clostridium butyricum, and A creomyces mucoides, primarily responsible for secondary bile acid conversion. Genetic background significantly shapes microbial community structure: Dahe black pigs exhibited higher abundance of Lactobacillus in the small intestine with enhanced primary bile acid hydrolysis capacity; Changdu Tibetan pigs demonstrated abundant secondary bile acid conversion-associated microbiota adapted to high-altitude coarse feeding conditions; whereas Dahe pigs maintain a balanced whole-intestinal microbiota composition with optimal stability in bile acid metabolism microecology. Microbial correlation analyzed revealed significant negative correlations between dominant Lactobacillus strains in the small intestine and anaerobic fermentation bacteria in the large intestine, while functional symbiotic bacteria within the same segment exhibited synergistic positive correlations. In conclusion, the interaction between pig breeds and intestinal segments collectively determines the differentiation of bile acid metabolism microbial communities, providing theoretical insights for breed conservation and precision nutrition formulation development.

Key words: local pig breed, intestinal segment, intestinal microorganism, bile acid metabolism, community structure