Effects of linolenic acid level on growth performance, digestive enzymes and antioxidant capacity of juvenile golden pompano (Trachinotus ovatus)

To determine the effects of dietary linolenic acid (LNA) level on growth performance, digestive enzymes and antioxidant capacity of juvenile golden pompano (Trachinotus ovatus), we assigned the fish ( 10.380.10)g randomly into six groups with three replicates per group and 20 fish per replicate. Six diets were formulated with six levels of LNA (dry matter, 0.13%, 0.59%, 1.10%, 1.60%, 2.10% and 2.50%) . The fish were fed twice daily for 56 d. The results show that the weight gain and specific growth rate (SGR) of fish fed diet with 0.59% and 1.10% LNA were significantly higher than those in group 2.1% and group 2.5%. Viscerosomatic index (VSI) , hepatosomatic index (HSI) , condition factor, abdominal fat and survival rate of fish were affected by dietary LNA levels significantly. The activity of pepsin of fish fed diet with 0.59% LNA was significantly higher than those fed with 0.13% and 2.50% LNA. The activity of amylase of fish fed diet with 1.10% LNA was significantly lower than those in the other groups. The total antioxidant capacity and catalase activity of serum showed an increasing trend and then decreased with increasing dietary LNA level. Quadratic regression analysis on SGR indicates that the optimum dietary LNA level for optimal growth of juvenile golden pompano was 1.04% of dry matter.