The effect of sustained swimming exercise on the growth performance, muscle cellularity and flesh quality of juvenile qingbo (Spinibarbus sinensis)

Abstract

This study was undertaken to investigate the effects of sustained swimming exercise on the growth performance, muscle cellularity and flesh quality of juvenile qingbo fish (Spinibarbus sinensis). Experimental fish were exercised under four water velocities, nearly still (control, 3cms−1) and 1, 2 and 4body lengths (bl)s−1, for eight weeks at 25°C. Then, growth performance indicated by the specific growth rate (SGR), white muscle cellularity suggested by the diameter and density of white muscle fiber, flesh quality evaluated by some textural mechanical properties (hardness, springiness, chewiness, cohesiveness) and physico-chemical parameters (pH, color, moisture, ash, protein, fat, amino acids, and fatty acids) were measured. Sustained swimming at moderate velocities (1 and 2bls−1) resulted in a significantly higher SGR and similar white fiber diameter and density compared with the controls. However, the fish trained at a water velocity of 4bls−1 displayed a similar SGR, smaller white fiber diameter and higher white fiber density compared with the controls. Sustained swimming resulted in significant increase in the values of pH and all textural traits but showed no significant effect on the color of the flesh for juvenile S. sinensis. Fish swimming under moderate water velocities exhibited higher levels of the protein content of the muscle, total essential amino acids (∑EAA) (at 2bls−1) and total amino acids (∑AA) (at 1 and 2bls−1) compared with control fish. However, the lowest levels of total amino acids (∑AA) and total n-6 poly-unsaturated fatty acids (∑n-6 PUFA) were observed in fish swimming at water velocity of 4bls−1. These data suggest that (1) moderate swimming exercise (1 or 2bls−1) improved growth performance, which could not be attributed to changes in white muscle cellularity; (2) sustained swimming showed a positive effect on texture characteristics, which was partly due to the higher white fiber density and flesh pH compared with controls; and (3) moderate swimming exercise (1 or 2bls−1) was beneficial for improving the nutritional quality of the flesh, whereas high-intensity swimming (4bls−1) resulted in an impairment of the nutritional quality of the flesh in juvenile S. sinensis. Statement of relevanceWe declare that the experiments complied with the current laws of the country in which the experiments were performed and that our paper complied with the laws of commercial aquaculture.