EFFECTS OF DIETARY INCLUSION OF FERMENTED SOYBEAN MEAL ON GROWTH, BODY COMPOSITION, ANTIOXIDANT ENZYME ACTIVITY AND DISEASE RESISTANCE OF ROCKFISH (Sebastes schlegeli)  

Two experiments were conducted to investigate the effects of replacing fish meal (FM) with fermented soybean meal (FSM) on growth performance, body composition, antioxidant enzyme activity and disease resistance of rockfish, Sebastes schlegeli, at the juvenile and grower stages. Five isonitrogenous (51%) and isocaloric (17.2 MJ kg^-1) diets were formulated to contain 0, 8, 16, 24 and 32% FSM (designated as FSM0, FSM8, FSM16, FSM24 and FSM32). Each experimental diet was fed to triplicate groups of juvenile (1.2 ± 0.04 g; EXP I) and grower (148.2 ± 2.9 g; EXP II) rockfish to visual satiation twice daily for 8 weeks. A trend of reduced growth performance and feed utilization efficiency with increased dietary levels of FSM was found in juvenile fish whereas grower fish did not show any definite pattern of change due to feed composition. The viscerosomatic index (VSI) of juvenile fish fed the diets containing 32% FSM was significantly lower than those of all the other experimental groups. Replacement of FM with FSM, up to 40%, had no significant effect on whole body and muscle proximate and amino acid compositions of juvenile and grower rockfish, respectively. The plasma antioxidant enzyme activity of grower fish was significantly enhanced by the dietary inclusion of the FSM compared with the control group. Survival of juvenile fish after intraperitoneal injection of Edwardsiella tarda was not affected by dietary treatment. These results indicate that FSM can be used successfully as a replacement for FM at levels up to 20% in diets for juvenile rockfish while at least 40% of dietary FM protein can be replaced by FSM without causing any adverse effect on grower rockfish performance.