Abstract
A 60 days feeding trial was conducted to investigate the effect of dietary high doses of vitamin E on Labeo rohita fingerlings. Five experimental diets were formulated to contain one control (VE0), two adequate levels of vitamin E supplementation, i.e. 100 and 150 mg/kg diet (VE100, VE150) and two high levels of vitamin E supplementation, i.e. 1000 and 1500 mg/kg diet (VE1000, VE1500). At the onset of feeding trial, 375 fish of nearly uniform initial body weight (3.58 +/- 0.04 g) were distributed in fifteen experimental tanks in the way that each dietary treatment was fed in triplicates and each tank contained 25 fish. Upon termination of feeding trial, no significant differences were found for dry matter, crude protein, crude fat and ash content in fish body. Lipid peroxidation was determined in terms of thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activities. The minimum value of TBARS was recorded in VE150 group, which was increased again with supplementation of high vitamin E levels. Similarly, adequate supplementation levels (VE1000, VE1500) reduced the superoxide dismutase (SOD), catalase and glutathione peroxidase activities, which were increased by feeding high vitamin dosages. Supplementation of vitamin E decreased the saturated fatty acids (SFA) and monoenes while increased the poly unsaturated fatty acids (PUFA) compared to control group. Similarly, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexanoic acid (DHA), total n-3 PUFA and total n-6 PUFA, arachidonic acid (ARA)/EPA, EPA/DHA, n3/n6 ratios were increased in muscle of fish fed vitamin E supplemented diets. However, differences between adequate and high doses of vitamin E were not significant for most of the fatty acids. In conclusion, dietary vitamin E supplementation reduced the lipid peroxidation which lead to increased PUFA contents in L. rohita. However, high doses of vitamin E showed the pro-oxidative effect which promoted lipid peroxidation.