The Pacific white shrimp is the most economically valuable shrimp species among crustacean aquaculture species. The fast growth, disease resistance, and tolerance for a wide range of water temperature and salinity are the key characteristics of the shrimp species cultures . Vitamin E, as an essential micro-nutrient, plays important roles in various physiological and biochemical processes. Vitamin E maintains and enhances the growth, innate immunity and antioxidant capacity of fish and shrimp. Thus, t his study was conducted to determine the dietary vitamin E requirement for Pacific white shrimp post-larvae.
The basal diet (E0) was prepared using soybean meal, fish meal and fish oil (protein, 32.5%; lipid, 9.20%). Four other diets were prepared by adding vitamin E (DL-α-tocopherol acetate) of 40 , 80 , 120 and 160 mg/kg to the basal diet (designated as E40 , E80 , E120 and E160 , respectively). Each diet was randomly assigned in quadruplicate group s of each 50 shrimp (3.95 ± 0.21 m g) and fed to the shrimp for 34 days.
The growth performance and feed utilization efficiency (FCR, PER) were significantly increased by vitamin E supplementation. The survival was the lowest in E0 group (65%), but no significant difference was found. Relative mRNA expression levels of insulin-like growth factor-binding protein, amylase, chymotrypsin and superoxide dismutase genes were significantly increased in shrimp fed vitamin E supplemented diets than in shrimp fed E0 diet. Shrimp fed E80, E120 and E160 diets had significantly higher resistance to ammonia than shrimp fed E0 diet. Broken line regression analysis indi cated that the optimum vitamin E level of the shrimp post-larvae would be 60.5 mg/kg diet.