Dietary resveratrol improves meat quality and antioxidant capacity of Tibetan sheep by regulating muscle fiber characteristics and mitochondrial function.

Combining metabolomics and proteomics, this study aimed to investigate the effects of resveratrol (RES) on meat quality, antioxidant capacity, muscle fiber characteristics and mitochondrial function in Tibetan sheep. Thirty healthy, 10-month-old male Tibetan sheep (33.87 ± 1.65 kg) were divided into three treatments: CON (basal diet), ResL (basal diet + 80 mg/kg RES), and ResH (basal diet + 360 mg/kg RES; n = 10). The experiment had a prefeeding period of 10 d and a treatment period of 84 d. Dietary RES supplementation significantly improved meat quality by decreasing shear force and drip loss, and increasing crude protein content (P < 0.05). For antioxidant capacity, RES enhanced SOD and GSH-Px activities (P < 0.05), upregulated SOD1, SOD2, and Nrf2 (P < 0.05), and downregulated Keap1 expression (P < 0.01). Regarding muscle fiber traits, RES promoted slow-twitch fiber proportion, upregulated MyHC IIa, IGF-1 and mTOR, while downregulating MyHC IIx and FoxO3 expression (P < 0.05). For metabolic regulation, RES did not alter lactate or glycogen levels (P > 0.05), but increased glucose content, reduced pyruvate kinase (PK) activity, and enhanced hexokinase (HK), succinic dehydrogenase (SDH), NAD-dependent malate dehydrogenase (NAD-MDH), and mitochondrial respiratory chain complex (MRCC) II/III activities, along with upregulating NRF1 and TFAM expression (P < 0.05). Metabolomic and proteomic analyses revealed that key proteins (PKM, PFKM, PGM1, PGAM2, HADHB, NDUFA8, NDUFS4, and GOT2) and differential metabolites (4-methylene-L-glutamine, anserine, betaine aldehyde, and N1-Methyl-2-pyridone-5-carboxamide) were closely correlated with muscle antioxidant capacity, mitochondrial function and meat quality (P < 0.05). In summary, RES collaboratively regulates muscle energy metabolism, muscle fiber type transformation and antioxidant capacity by modulating key glycolytic and mitochondrial respiratory chain proteins, as well as critical metabolites, ultimately enhancing the meat quality of Tibetan sheep.