Effect of different levels of dietary protein and water salinity on antioxidant enzymes of white leg shrimp (Penaeus vannamei) juveniles

In this study, effect of different levels of dietary protein (25, 35 and 45 per cent) and water salinity (0-3, 12-15 and 32-35 ppt) on antioxidant enzymes of white leg shrimp (Penaeus vannamei) was studied. 324 P.vannamei (with mean weight±SE: 5.55 ± 0.18 gr) were randomly distributed in twenty seven tanks. Experimental shrimps were fed by formulated diets for 56 days and at the end of the experiment, total antioxidant capacity (T-AOC) and activity of super oxidase dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) of hepatopancreas and muscle tissue were measured. The results showed significant difference in antioxidant enzymes activity of experimental shrimps among different treatments. This study showed that increasing trend on levels of dietary protein (especially 45%) at different water salinity, cause oxidative stress and increase the activity of antioxidant enzymes. Also, changes in water salinity from 32-35 to 12-15 and 0-3 ppt significantly increased (P>0.05) the activity of antioxidant enzymes in the hepatopancreas and muscle tissue of white leg shrimp. In general, level of 35% dietary protein and salinity of 32-35 ppt are appropriate conditions for culturing of juveniles of white leg shrimp.