Multi-omics reveals associations between feed efficiency, physiological traits and meat quality in slow-growing...

1. A total of 450 male chickens were individually housed and assessed for residual feed intake (RFI) and feed conversion ratio (FCR) over a 28 d feeding trial, with subsequent phenotypic measurements and breast muscle samples collected from selected high- and low-efficiency groups for metabolomic and lipidomic profiling.2. Residual FI had significant correlations with faecal volume, behavioural activity and head temperature, while FCR showed only a negative correlation with head temperature. Meat quality analysis revealed that residual FI correlated with breast muscle shear force, while FCR was associated with thigh muscle colour parameters.3. Multi-omics profiling of breast muscle showed distinct metabolite and lipid compositions between efficiency groups, and FCR was linked to triacylglycerol content and residual feed intake (RFI) to glycerophospholipid levels.4. This trial demonstrated that feed efficiency influences both physiological processes and meat quality, providing a basis for balanced breeding strategies in slow-growing poultry.