Dietary Supplementation with Hesperidin and Rosmarinic Acid Improves Meat Quality, Modulates Gut Microbiota, and Enhances Antioxidant Capacity in Finishing Pigs

Enhancing meat quality and optimizing pork-free amino acid profiles can boost the industry competitiveness of pork. Plant-extracted phenolic substances have beneficial effects on meat quality. This study evaluated the effects of dietary supplementation with hesperidin, rosmarinic acid, and their combination on meat quality in finishing pigs. Twenty-four pigs were divided into four dietary treatment groups: CON (basal diet), HES (basal diet supplemented with 600 mg/kg hesperidin), RA (basal diet supplemented with 40 mg/kg rosmarinic acid), and HES-RA (basal diet supplemented with 300 mg/kg hesperidin and 20 mg/kg rosmarinic acid). After 90 days, pigs were slaughtered and sampled following a 12 h fast. Compared with the CON group, the HES-RA group pigs exhibited a significant increase in pH45 min and meat color a*, and had a decrease in meat color L* and drip loss. The combined HES-RA supplementation significantly increased the activities of glutathione peroxidase, total antioxidant capacity, and total superoxide dismutase, while reducing malondialdehyde. Furthermore, the contents of arginine and leucine were elevated in the muscle and serum. This combination treatment also modulated the ileal microbiota composition, notably enriching short-chain fatty acid-producing genera such as Veillonella and Mitsuokella, and increased the concentrations of acetate, propionate, and butyrate in the ileum. Furthermore, the combined supplementation significantly elevated the muscle mRNA expression of GLUT4, mTOR, S6K1, and 4E-BP1. Collectively, the hesperidin and rosmarinic acid supplementation was associated with enhanced meat quality, along with improved antioxidant capacity, modulation of gut microbiota and SCFA production, and upregulation of mTOR-associated gene expression.