Antibiotic-free Wenchang chickens may promote blood levels of B vitamins by modulating the gut microbiota: An integrated analysis of cecal content metagenomics and serum metabolomics

Through the selective breeding of superior strains, livestock and poultry can achieve enhanced disease resistance and production performance, thereby improving farming efficiency and increasing chicken meat yield. This study analyzed the expression of gut health-related genes, cecal microbiota, and untargeted serum metabolomics in Wenchang chickens from the NS strain (Normal strain) and the AFS strain (Antibiotic-free strain), and explored the relationships between their cecal microbiota and serum metabolites. Our results show that in the ileum, antioxidant-related indicators T-AOC (P < 0.05), T-SOD (P < 0.05), and GSH-PX (P < 0.05) were significantly higher in the AFS strain than in the NS strain, while MDA (P < 0.05) was significantly lower in the AFS strain than in the NS strain. The mRNA expression level of RORγt/FoxP3, which is related to immune regulation, was significantly lower in the AFS strain than in the NS strain (P < 0.05). The differential microorganisms in the cecum primarily included Muribaculum, Cryptobacteroides, Blautia, Enterocloster, Lachnoclostridium, Hydrogenoanaerobacterium, Ruminococcus, Subdoligranulum, Clostridioides, and Evtepia. The main differential metabolites in serum included folinic acid, biotin, lysophosphatidic acid (LPA), 3-hydroxy-3-methylbutanoic acid, 3-hydroxybutyric acid, and others. The differential metabolites are primarily enriched in the following metabolic pathways: gap junction, glycolipid metabolism, and fatty acid biosynthesis. In addition, the Pearson correlation analysis between the gut microbiota and serum metabolites showed that Blautia was positively correlated with folinic acid (P < 0.05) and biotin (P < 0.05); Lachnoclostridium was positively correlated with biotin (P < 0.01); and Ruminococcus was positively correlated with 3-hydroxybutyric acid (P < 0.05). This study mainly elucidates the metabolic characteristics of the antibiotic-free Wenchang chicken strain by analyzing gut microbiota and serum metabolites.