Integrated Multi-Omics Analysis Reveals the Role of the Gut Microbiota–Metabolite–Endocrine Axis in Post-Weaning Estrus Recovery in Tibetan Pigs

The weaning-to-estrus interval (WEI) is an important indicator of sow reproductive performance, yet the mechanisms underlying post-weaning anestrus in Tibetan sows remain unclear. In this study, multiparous Tibetan sows were classified into an estrus group (FQ) and an anestrus group (WQ) based on estrus status after weaning. Serum reproductive hormones, hematological parameters, gut microbiota (16S rRNA sequencing), and fecal metabolites (untargeted metabolomics) were analyzed. Compared with the FQ group, the WQ group showed significantly lower estradiol (E2) and higher progesterone (P) levels (p < 0.01), along with a decreased proportion of neutrophils and an increased proportion of lymphocytes (p < 0.05). No significant differences in alpha diversity were observed, whereas PLS-DA revealed differences in microbial community structures between groups. LEfSe analysis indicated that Methanobrevibacter and Acinetobacter were enriched in the FQ group, whereas Muribaculaceae and Prevotella were enriched in the WQ group. Differential metabolites were mainly involved in amino acid and lipid metabolism and enriched in pathways related to steroid hormone biosynthesis, oocyte maturation, and tryptophan metabolism. These findings suggest that post-weaning anestrus may be associated with endocrine imbalances, immune changes, and gut microbiota–metabolite interactions. They may provide a basis for future studies in Tibetan pig breeding and genetic improvement.