Intestinal Development in Wuzhishan Pigs at Different Growth Phases: Insights from Microbiome and Metabolomics

Wuzhishan pigs are a typical Chinese indigenous miniature pig breed, with thin skin and high amino acid content in muscle; slow weight gain and long feeding phases limit their value. As the primary digestive and absorptive organ, the intestine is crucial for growth, yet current studies on its development are limited. This study aimed to investigate intestinal physiological differences in Wuzhishan pigs across four phases (pre-weaning: 7, 14 days; weaning: 35, 38, 45 days; fattening: 70, 100 days; maturity: 180, 240 days) by evaluating intestinal morphology, digestive enzyme activity, gut microbiota diversity via 16S rRNA gene sequencing, and metabolite characteristics via metabolomic analysis. Results showed poor intestinal morphology and enzyme activity during weaning, significant ileal and colonic microbial diversity differences across phases, increased beneficial bacteria with age, and enriched opportunistic pathogens (<i>Streptococcus</i>, <i>Romboutsia</i>, <i>Terrisporobacter</i>) during weaning; weaning also had lower lipid metabolites, correlated with decreased <i>Fusobacterium</i>, <i>Lactobacillus</i>, and <i>Muribaculaceae</i>. Fattening enhanced amino acid metabolism, with increased <i>Lactobacillus</i> correlated with higher amino acids and muscle-related metabolites, while maturity increased immune-related metabolites (e.g., pyridoxine) in the vitamin B6 pathway. These results explain delayed rapid weight gain in Wuzhishan pigs and provide a theoretical basis for maintaining intestinal stability and production performance.