Effects of dietary ethoxyquin on growth, feed utilization and residue in the muscle of juvenile Japanese seabass, Lateolabrax japonicus

摘要

Ethoxyquin (EQ) is the most common synthetic antioxidant used for preventing rancidity in fish foodstuffs. However, literature related to the effects of dietary EQ on performance of fish was limited. The present study was conducted to investigate the effects of EQ on performance and EQ residue in muscle of juvenile Japanese seabass Lateolabrax japonicus and to estimate the optimal EQ concentration in the diet. Graded levels [0 (control), 50, 150, 450 and 1350mg EQkg(-1) diet] of EQ were added to the basal diet, resulting in five dietary treatments in the experiment. Each diet was fed to triplicate groups of seabass (initial body weight 8.01 +/- 0.76g) for 12weeks in floating sea cages (1.5x1.5x2.0m, 30 fish per cage). Survival ranged from 78.9 to 86.7%, and was irrespective of dietary EQ levels. The specific growth rate (SGR) of fish fed diets supplemented with 50mgkg(-1) EQ had significantly (P0.05) higher SGR than fish fed diets supplemented with 150mgkg(-1) EQ, the highest SGR was observed in fish fed diet with 50mgkg(-1) EQ supplementation. Feed intake (FI) and feed efficiency (FE) were not significantly (P>0.05) different among dietary treatments. Fish fed diets with 50 and 1350mgkg(-1) EQ had a significant (P0.05) lower body lipid content than fish in the control group. Muscle EQ level significantly increased when dietary EQ increased. Optimal EQ concentration estimated by polynomial regression based on maximum growth of juvenile Japanese seabass was 13.78mgkg(-1) diet.