Effects of dietary branched-chain amino acid supplementation on growth and skeletal muscle cellularity in Japanese amberjack Seriola quinqueradiata

Abstract

The present study investigated a determination method for skeletal muscle fiber diameters in Japanese amberjack Seriola quinqueradiata. We also investigated the effects of two supplements, a mixture of branched-chain amino acids (BCAAs) and valine alone, on body growth and skeletal muscle cellularity. The minor distances between two points on randomly selected individual fibers were measured and termed fiber diameters. Using growing fish (ranging from 4.8 g to 194.0 g in body weight), body weights and median fiber diameters were significantly correlated. A BCAA-supplemented diet (valine:leucine:isoleucine, 1:2:1) significantly increased the body weight after 105 days. The distribution frequency of fiber diameters between 61 and 81 μm was significantly higher in the 1 % BCAA group (P < 0.05) than in the control. However, dietary valine supplementation (1 %) had no effect on growth or skeletal muscle cellularity. These results indicated that hypertrophic growth occurred in the skeletal muscle of Japanese amberjack and was affected by dietary supplementation with a BCAA mixture.