Effects of dietary vitamin E supplementation on growth, feed utilization and flesh quality of large yellow croaker Larimichthys crocea fed with different levels of dietary yellow mealworm Tenebrio molitor meal

Abstract

An 80-day feeding trial was conducted to evaluate the effect of dietary vitamin E and replacement levels of dietary fish meal (FM) by yellow mealworm Tenebrio molitor (TM) meal on growth, feed utilization and flesh quality of large yellow croaker Larimichthys crocea (initial body weight: 189.20 ± 0.16 g). Six isonitrogenous and isolipidic diets from a two factorial design of 3 × 2 were formulated with three replacement levels of dietary FM by TM (15%, 30% and 45%, respectively) and two levels of vitamin E (150 mg/kg and 500 mg/kg), respectively. The results showed that the growth and feed utilization of large yellow croaker were significantly decreased at 45% replacement level of dietary FM by TM (P < 0.05). Vitamin E supplementation significantly improved the growth and feed utilization, and increased the content of crude protein, vitamin E and ∑n-3 poly-unsaturated fatty acids in the flesh at higher dietary replacement level (>30%) of FM by TM (P < 0.05). Yellowness (b*) in the dorsal, caudal and ventral skin were found to be significantly increased with the increasing dietary vitamin E supplementation (P < 0.05). Protein carbonyl, malondialdehyde, and fiber density significantly decreased at 500 mg/kg of dietary vitamin E, while hardness, gumminess, chewiness and the activities of superoxide dismutase, glutathione-peroxidase, catalase in flesh significantly increased (P < 0.05). The transcript levels of MyoD and myf5 were significantly affected by dietary vitamin E levels (P < 0.05). The present study indicated that 30% of dietary replacement level of FM by TM was practicable in large yellow croaker feed. Meanwhile, dietary vitamin E supplementation improved the flesh quality of large yellow croaker.