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This study investigated the gut-muscle axis in aged laying hens by applying multi-omics analyses to compare hens fed a Caldifermentibacillus hisashii-containing fermented feed against a control diet. The researchers found that fermented feed administration drove a marked expansion of Lactobacillus and substantially shifted both the faecal and muscle metabolomes, with gut microbiota sharing considerable variance with both compartments. Key metabolic signals included depletion of proteolytic bacteria and faecal amino acids, reduced muscle ornithine and uric acid, and elevated hypoxanthine, collectively interpreted as evidence of enhanced host amino acid utilisation and efficient nitrogen turnover rather than accumulation.
Why it matters
Understanding the gut-muscle axis in livestock species could inform feeding strategies aimed at improving muscle quality and metabolic health in aged production animals, with potential economic benefits for the laying hen industry. More broadly, this work offers a statistically grounded framework that may be extended to other livestock models and, cautiously, to comparative studies in aging biology.
arXiv:2605.19171v1 Announce Type: new
Abstract: The gut-muscle axis has been proposed to link gut microbiota with skeletal muscle physiology, yet its universality across livestock species remains unclear. Using aged laying hens, a livestock model with a relatively short digestive tract, we examined the gut microbiota, faecal metabolome, and breast-muscle metabolome by integrative multi-omics analyses in hens fed a Caldifermentibacillus hisashii-containing fermented feed or a control diet. Non-metric multidimensional scaling revealed clear separation of the microbial community between groups (stress = 0.0097), characterised by a marked expansion of Lactobacillus with the administration of the fermented feed. Variance partitioning showed that the 16S microbiota shared substantial variance with both the faecal (shared R2 adj = 0.54) and muscle (shared R2 adj = 0.48) metabolomes, and partial dbRDA demonstrated that the faecal-to-muscle metabolite association was largely retained after controlling for 16S (direct R2 = 0.538, partial R2 = 0.485), consistent with faecal metabolites acting as an integral layer linking microbiota to muscle. Cliff’s delta-based selection showed depletion of proteolytic taxa and faecal amino acids, and reduced muscle Ornithine and uric acid alongside elevated Hypoxanthine. Because both groups were processed identically post-slaughter, these differences reflect in vivo states: amino acid depletion despite reduced bacterial proteolytic capacity points to enhanced host utilisation, and reduced uric acid, a post-mortem-stable purine end-product in uricotelic chickens, indicates efficient nitrogen turnover rather than accumulation. Collectively, these findings support a putative tripartite model of the gut-muscle axis in aged laying hens, providing a statistically grounded framework for understanding microbial contributions to muscle physiology in aged livestock.
Source: A putative model of the gut-muscle axis in aged livestock