Effects of dietary vitamin E supplementation on growth performance, fatty acid composition, lipid peroxidation and peroxisome proliferator-activated receptors (PPAR) expressions in juvenile blunt snout bream Megalobrama amblycephala.

Abstract

A 9-week feeding experiment was conducted to evaluate the effects of dietary vitamin E (VE) supplementation on growth performance, liver fatty acid composition, lipid peroxidation and peroxisome proliferator-activated receptors (PPAR) genes expressions in blunt snout bream juveniles. Fish (average initial weight: 0.59g) were fed diet supplemented with 0, 50, 100, 300 and 500mg α-tocopherol acetate/kg in triplicates, which were found to, respectively, contain 11.2, 56.3, 114.6, 306.5 and 588.4mg α-tocopherol/kg diet. Results showed that final weight, body weight gain and specific growth rate significantly increased with increasing dietary VE supplemented level from 11.2 to 56.3mg/kg. When the broken-line model was employed to estimate the adequate requirement of vitamin E based on body weight gain, the optimal level was 55.5mg/kg in diet. Hepatosomatic index value significantly decreased with incremental dietary VE levels. However, liver VE concentration showed a direct relationship with the dietary VE level. The percentages of 20:5n-3, 22:6n-3 and total n-3 long chain polyunsaturated fatty acids in liver increased with increasing dietary VE supplementation. Meanwhile, the expressions of PPAR-α, PPAR-β and PPAR-γ in liver were down-regulated by supplementation of dietary VE level from 56.3 to 588.4mg/kg. In conclusion, supplementation of more than 55.5mg/kg vitamin E may improve growth and increase n-3 LC-PUFA content in blunt snout bream, which is beneficial to human consumer.