Theoretical and Empirical Contributions to the Interplay Between Gut Microbiota Composition and Serum Metabolite Profiles in Indigenous Chickens Under Extensive Management in North East Nigeria

The relationship between gut microbiota composition and host metabolic biochemistry in indigenous poultry under traditional management conditions represents a frontier of veterinary physiology with profound implications for sustainable production in low-input systems. This study made original theoretical and empirical contributions to characterising the gut microbiota-serum metabolome axis in indigenous village chickens under extensive management in Adamawa and Borno States, North East Nigeria. One hundred and fifty adult indigenous chickens sampled during three seasonal periods were subjected to metagenomic analysis of ileal and caecal contents by 16S ribosomal RNA gene sequencing alongside serum untargeted metabolomics by liquid chromatography-mass spectrometry. A theoretical model proposing seasonal foraging-driven microbiota shifts as upstream determinants of host tryptophan, short-chain fatty acid, and bile acid metabolism was constructed and tested by structural equation modelling. Seasonal variation in ambient temperature and diet diversity drove significant shifts in the Firmicutes-to-Bacteroidetes ratio. Microbiota diversity scores correlated positively with serum indole and bile acid metabolite concentrations, which in turn predicted circulating immunoglobulin A levels. Tryptophan-derived serotonin precursors were elevated in rainy season chickens with the highest microbial diversity. This study provides the first gut microbiota-metabolomics integrated dataset for Nigerian indigenous chickens and advances a theoretical microbiota-immunity axis framework applicable to traditional poultry systems in North East Nigeria. Keywords: gut microbiota, serum metabolomics, indigenous chickens, tryptophan metabolism, North East Nigeria.