Effect of swimming training on the flesh quality in Chinese Perch (Siniperca chuatsi) and its relationship with muscle metabolism

This study aims to explore the effect of swimming training on the muscle quality of Chinese Perch (Siniperca chuatsi) and the relationship between flesh quality characteristics and metabolism. A total of 240 Chinese Perch with an initial weight of 70.66 & PLUSMN; 0.34 g were divided into four groups, the control [CK, 0 body length per second (bl/s)], low flow velocity (LF, 0.4 bl/s), middle flow velocity (MF, 0.8 bl/s) and high flow velocity (HF, 1.2 bl/s) groups, for a 56-day experiment. The results showed that swimming training significantly improved the gumminess, chewiness, resilience, adhesiveness and hardness of muscles and increased the density of muscle fibers. Compared with the other groups, the MF group had stronger antioxidant capacity and larger muscle fiber diameter. Regarding nutrition-related indicators, the content of crude protein, essential amino acids (EAAs) and delicious amino acids (DAAs) in muscle increased significantly under 1.2 bl/s exercise intensity. However, the content of polyunsaturated fatty acids (PUFAs) in the HF group decreased significantly. At the same time, with increasing flow velocity, the mRNA expression of protein catabolism-related genes was significantly upregulated, while the mRNA expression of lipid metabolism-related genes decreased significantly. The metabolomics results showed that under 1.2 bl/s exercise intensity, the KEGG functional pathway was mainly mapped to amino acid metabolism and carbohydrate metabolism. At this flow velocity, most lipids and their derivatives in metabolites were downregulated, and most amino acids and their derivatives were upregulated. Therefore, moderate swimming training will help to provide healthier and more nutritious aquatic products.