Abstract：To explore the molecular mechanism by which feeding methods regulate post-slaughter meat quality through mitochondrial oxidative stress, this study used proteomic analysis to compare the quality and mitochondrial status and function of muscle fibers in lamb meat from sheep under high-concentrate fattening and grazing feeding conditions. Ten hybrid lambs of Mongolian sheep and small-tailed Han sheep were selected and randomly divided into two groups (n = 5): PF (pure grazing on natural grassland without concentrated feed supplementation) and HC (fed on a basal diet composed of roughagfeed mixed with forage and concentrated supplement). After completion of the feeding trial, the lambs were slaughtered and the longissimus dorsi muscle was collected for analysis. It was found that there were differences in nutrient contents between the two groups of lamb meat. Compared with grazing, high-concentrate feeding resulted in lower redness value (a*) and poorer oxidative stability of lamb meat. In the HC group, the oxidative stress damage to mitochondria in muscle fibers was more severe, manifested by increased reactive oxygen species (ROS) content, enhanced mitochondrial lipid peroxidation, Ca2+ overload, and increased mitochondrial membrane permeability. Proteomic analysis revealed that compared with the PF group, 25 differentially expressed proteins (DEPs) were found in the mitochondrial oxidative phosphorylation pathway in the HC group, among which 19 were enriched in mitochondrial complex I (CI) (subunits such as NDUFV2 and NDUFA4 were significantly upregulated). The abnormal expression of mitochondrial CI may disrupt the electron transport chain, leading to electron leakage and promoting the generation of ROS. This in turn induces a positive feedback loop of “oxidative stress-mitochondrial apoptosis”, ultimately leading to protein oxidation and changes in meat quality.
2026, Vol. 40 
