Effects of dietary vitamin E levels on growth performance, serum antioxidant capacity, and muscle fatty acid composition of Japanese seabass (Lateolabrax japonicus)

A 9-week feeding trail evaluated the effects of graded vitamin E (VE) supplementation (0–320 IU/kg) on growth, whole-body composition, serum antioxidants, and muscle fatty acids in Japanese seabass (10.20 ± 0.14 g). Dietary VE levels significantly influenced survival rate, weight gain rate, specific growth rate (SGR), feed efficiency, and protein efficiency ratio, with optimal efficacy achieved at 84.7 IU/kg. Hepatic VE concentration and systemic antioxidant activities, including catalase, superoxide dismutase, glutathione peroxidase, and total antioxidant capacity, demonstrated significant dose-responsive elevation ( p < 0.05), reaching peak values at 323.6 IU/kg dietary VE. The VE-deficient group (14.2 IU/kg diet) exhibited a significant reduction in hepatic crude lipid content, whereas whole-body proximate composition and hepatosomatic index showed no significant differences across the six dietary VE levels. Furthermore, Japanese seabass maintained on VE-deficient regimens displayed elevated muscle saturated fatty acid proportions concurrent with reductions in polyunsaturated fatty acids and docosahexaenoic acid. VE supplementation (32.2–323.6 IU/kg diet), conversely, ameliorated these adverse lipid profile alterations ( p < 0.05). Optimal dietary VE requirements for Japanese seabass were quantified at 88.35 IU/kg based on cubic regression of SGR and at 250.2 IU/kg through second-order polynomial modeling of hepatic VE concentration.