Chlorogenic acid mitigates high stocking density-induced breast muscle quality decline in broilers via modulating mitochondrial redox homeostasis and glycolytic metabolism

High stocking density ( HD ) in intensive poultry farming induces oxidative stress and mitochondrial dysfunction, leading to compromising meat quality. This study explored the potential role of chlorogenic acid (CGA) as a protective dietary supplement for improving breast muscle quality under HD conditions. In total, 510 broilers were reared under either normal density (14 birds/m², ND) or HD (22 birds/m²), with 0.0, 0.5, 1.0 or 1.5 g/kg CGA added to the HD group. After 42 days, exposure to HD led to a substantial 12% ( P  < 0.05) decrease in body weight, a significant ( P  < 0.05) rise in feed conversion ratio ( FCR ), and deterioration in meat quality as evidenced by a marked decrease in pH, a rise in cooking and dripping losses, and unfavorable alterations in meat color ( L* , a* , b* ) ( P  < 0.05). Supplementation with 0.1% CGA significantly alleviated HD-induced growth suppression and enhanced antioxidant defenses by reducing the levels of malondialdehyde ( MDA ) and reactive oxygen species ( ROS ) ( P  < 0.05), while boosting glutathione peroxidase ( GSH-Px ) and superoxide dismutase ( SOD ) activities ( P  < 0.05).. Mechanistically, CGA alleviated mitochondrial dysfunction by downregulating heat shock proteins ( HSP60 , HSP70 ) and mitochondrial proteases ( CLPP , CLPX ) ( P  < 0.05), restored tricarboxylic acid ( TCA ) cycle activity (via increased SDH and MDH ), and shifted glycolytic flux toward aerobic metabolism. These findings highlight CGA as a promising feed additive for improving meat quality under HD stress through mitochondrial protection and metabolic reprogramming.