Proteomics- and Metabolomics-Based Investigation of the Effects of Astragalus membranaceus Powder on Meat Quality and Molecular Profiles of Longissimus dorsi Muscle in Ao-Hu Crossbred Rams

Astragalus membranaceus is a traditional Chinese medicinal herb commonly used as a feed additive in livestock production; however, the molecular mechanisms by which it influences meat quality in sheep remain poorly understood. In this study, 96 Ao-Hu crossbred rams were randomly allocated to four dietary treatments receiving 0%, 2%, 4%, or 6% Astragalus membranaceus powder (AMP) over a 70-day feeding trial. At the end of the trial, one sheep per pen (n = 6 per treatment) was selected for longissimus dorsi muscle collection and subsequent meat quality traits, proteomic and metabolomic analyses. Phenotypically, only the 6% AMP inclusion significantly reduced cooking loss, while all the other quality traits remained unchanged. Metabolomic analysis identified 24, 33, and 86 differential metabolites in the low-, medium-, and high-dose groups, respectively, with the high-dose group showing additional enrichment in arginine-proline metabolism, pantothenate/CoA biosynthesis, and cAMP/cGMP signaling pathways. Proteomic analysis revealed 11, 7, and 19 differentially expressed proteins, with collagen family members (COL1A1, COL1A2, and COL3A1) down-regulated exclusively at the high dose, though shear force was unaffected. Correlation analysis suggested associations between cooking loss and metabolites involved in fatty acid oxidation and redox balance. These findings provide clues for understanding the effects of AMP on meat quality and offer candidate pathways and protein targets for future mechanistic investigations.