Multi-omics insights into isovaleric acid effects on broiler performance, physiological health, and meat quality

Isovaleric acid (IVA) has been shown to benefit gut health, but its effects on broiler meat quality remain unclear. A total of 864 broilers were assigned to control or 0.05%, 0.1%, or 0.2% IVA groups to evaluate the effects of IVA supplementation on performance, blood biochemistry, immunity, gut microbiota, metabolome, and meat quality. IVA increased average daily gain and, at some doses, feed intake and villus height, while reducing feed conversion ratio. It also lowered serum blood urea nitrogen at 21 and 42 days and modulated inflammatory and immune indices. IVA improved meat quality by increasing breast and leg muscle protein content at 42 days, reducing drip loss and shear force, and improving color parameters. Microbiome analysis showed that IVA reduced Ace index and altered bacterial and fungal β-diversity at 21 days, whereas at 42 days it increased bacterial Shannon index and shifted community composition, while fungal α-diversity remained largely unchanged. Metabolomics revealed marked changes in lipid and amino acid metabolism. Integrative analysis identified Collinsella, norank_f__Ruminococcaceae, and unclassified_f__Oxalobacteraceae as key taxa associated with beneficial muscle metabolites. These findings highlight a gut microbiota-metabolome-muscle axis contributing to improved broiler meat quality and inform nutritional interventions in poultry production.