Gut microbiota-derived propionic acid mitigates age-related albumen quality deterioration by modulating magnum...

The declined albumen quality during the late laying phase is associated with age-related magnum dysfunction, in which to the roles of gut microbiota is unclear. This study aimed to elucidate the relationship between gut microbiota and magnum function, and its impact on albumen quality. Hy-Line Brown layers at peak (30 wk) and late (70 wk) laying phases were compared to assess age-related changes in albumen quality, magnum function, and gut microbiota. Fecal microbiota transplantation (FMT) from peak- to late-phase hens was conducted to assess functional effects. Microbiome and metabolome analyses were then integrated to identify key bacterial taxa and metabolites. The role of the leading candidate metabolite was further validated through dietary supplementation. Results showed that late-phase hens exhibited significant reductions in albumen height, magnum mucosal fold height, and tubular gland diameter (P < 0.05), alongside gut microbial dysbiosis. FMT from peak-phase donors effectively reversed age-related declines in magnum histomorphology and albumen height in late-phase hens. It also up-regulated the expression of barrier function genes (Claudin-1, ZO-2, MUC2, AGR2) and magnum secretory markers (OVOA), while down-regulating pro-inflammatory cytokines (IL-4, IFN-γ) (P < 0.05). Microbial analysis identified Anaerotruncus as the only genus consistently enriched following FMT and positively correlated with improved albumen height and magnum morphology. Metabolomic analysis revealed that propionic acid was the top metabolite associated with Anaerotruncus abundance. Crucially, dietary supplementation with sodium propionate recapitulated the key benefits of FMT. In summary, our findings revealed a gut microbiota-oviduct axis through which microbiota from peak-laying hens ameliorate age-related magnum decline and improve albumen quality in aging hens.