Multi-omics insights into the role of microencapsulated sodium butyrate on production performance in aged quails

This study investigated the effects of microencapsulated sodium butyrate (MSB) on production performance, reproductive hormone profiles, and gut microbiota-metabolite interactions in late-laying quails. Dietary MSB supplementation significantly increased laying rate and early egg weight and elevated serum FSH and LH concentrations, suggesting a potential involvement of reproductive endocrine regulation. MSB enhanced gut microbial richness and enriched fiber-fermenting, SCFA-associated taxa such as Lachnospiraceae, Ruminococcaceae and Bacteroides, while co-occurrence network analysis revealed increased connectivity and robustness of the microbial community. Untargeted metabolomics showed coordinated changes in amino acid derivatives, short peptides and lipid-like molecules. Exploratory mediation analysis further suggested that specific metabolites may be involved in the associations between MSB-responsive bacteria and host reproductive traits. Specifically, the dipeptide Pro-Trp and N-arachidonoyl phenylalanine were potentially associated with the relationship between decreased s__uncultured_bacterium_o__RF39 and improved laying rate, whereas N-docosahexaenoyl tryptophan appeared to link increased s__unclassified_f__Lachnospiraceae to higher FSH concentrations. These findings indicate that MSB may improve reproductive performance in aging quails by reshaping the gut microbiota and its metabolite outputs in a manner that supports reproductive endocrine function. Overall, this study provides novel insights supporting the use of microencapsulated sodium butyrate as a functional feed additive for extending the productive lifespan of laying quails.