Dietary (−)-Epicatechin supplementation regulates myofiber development, fillet quality, and antioxidant status of Yellow River carp (Cyprinus carpio)

(−)-Epicatechin (EC) exhibits antioxidant effects and strengthens skeletal muscle growth and differentiation in mammals. However, there are no reports about the effects of EC in fish. This study evaluated the effects of EC on muscle antioxidant capacity, myofiber development, texture characteristics, and histomorphology were also investigated through feeding trial. 300 fish (16.27 ± 0.24 g) were fed four diets with different levels of EC (0, 100, 500, and 1000 mg/kg) for 60 days. The result showed that 1000 mg/kg EC supplementation enhanced antioxidant capacity and protein content in the muscle. Meanwhile, higher expression levels of proliferating cell nuclear antigen (pcna), myogenic differentiation antigen (myod), myogenin, myosin myosin heavy chain (myhc), and myosin light chain (mylc) were detected in the muscle of EC treatment, while the myostatin (mstnb) mRNA level was decreased in the EC 1000 group, the similar trends were observed in the protein expression levels of MyoD, Myogenin, MyLc (P < 0.05). Muscle hardness and pH value were increased significantly in EC 500 and 1000 groups (P < 0.05). Additionally, myofiber density, small-sized fiber percentage, and expression of genes related to AMP-activated protein kinase (AMPK) signaling pathway was promoted in the EC groups. These results indicated that dietary EC improved fillet quality and promoted myofiber development in Yellow River carp, which might be related to AMPK pathway.