VITAMIN E SUPPLEMENTATION IN PRACTICAL DIET OF Labeo rohita FINGERLINGS

Abstract

The effect of dietary vitamin E supplementation in practical diet of Labeo rohita fingerlings was experimentally evaluated in this study. The study was conducted in three feeding trials which lasted 60 days each. The basal diet was same for all feeding trials. In the first feeding trial, two adequate levels (100, 150 mg/kg) and two high levels (1000, 1500 mg/kg) of vitamin E with a control level (0 mg/kg) were fed in a completely randomized design (CRD). In the second trial, two levels of lipids (8 and 16%) and three levels of vitamin E (0, 100, 1000 mg/kg) were supplemented in a 2×3 factorial arrangement. In the third feeding trial, three levels of oil oxidation (11.7, 56.3, 111.5 meq/kg) and dietary vitamin E (0, 100, 1000 mg/kg) were used in an 3×3 factorial arrangement. Adequate levels of dietary vitamin E increased growth performance of Labeo rohita when compared to the high levels of vitamin E. Also supplementation of vitamin E linearly increased the liver and muscle α-tocopherol level. The thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activities were decreased with adequate vitamin E supplementation, which increased proportionately with increase in vitamin E concentrations. The percentages of poly unsaturated fatty acids (PUFA) were higher in vitamin E supplemented diets than control. In the second feeding trial, fish fed the 16% lipid diets showed significantly higher growth than fish fed the 8% lipid diets. Increasing the dietary supplemental levels of fish oil decreased (p<0.05) the liver α-tocopherol content, but had no effect on muscle α-tocopherol level. The TBARS and antioxidant enzyme activities increased with increasing dietary fat levels. The PUFA percentages increased significantly with increased levels of dietary fish oil. In third feeding trial, growth of fish fed fresh fish oil and low oil oxidation level were significantly higher (p<0.05) than those of fish fed highly oxidized oil. Among highly oxidized oil (111.5 meq/kg) containing treatments, fish feeding on 1000 mg/kg vitamin E showed better growth performance. Oil oxidation caused a significant reduction in the concentrations of α-tocopherol in fish liver and muscles. Ingestion of oxidized oil resulted in higher TBARS levels, antioxidant enzyme activities and muscular PUFA, in particular, DHA while dietary vitamin E supplementation abrogated these effects. In conclusion, vitamin E supplementation reduced the lipid peroxidation, enhanced the growth performance and improved the meat quality of L. rohita fingerlings irrespective of the level and quality of fish oil; however, the required level of vitamin varied depending upon dietary level of fish oil and level of oil oxidation.