α-Tocopherol in weaning diets for European sea bass (Dicentrarchus labrax) improves survival and reduces tissue damage caused by excess dietary DHA contents

Abstract

The objective of the present study was to investigate the combined effect of several dietary contents of vitamin E and polyunsaturated fatty acids (PUFA), mainly docosahexaenoic acid (DHA), on growth, survival, biochemical composition and tissue morphology of sea bass along early development. A feeding experiment was conducted in sea bass larvae using five different diets with the same proximate composition and different ratios of DHA concentrated fish oil [10, 30 and 50 g kg−1 dry weight (DW)] and vitamin E (α‐tocopherol acetate) (1500 and 3000 mg kg−1 DW). DHA was readily deposited in fish tissues and associated with higher sea bass mortalities probably because of increased peroxidation risks. Besides, the elevation of dietary DHA contents up to 5% severely increased the incidence of muscular lesions and the presence of ceroid pigment within hepatocytes. However, elevation of dietary vitamin E levels markedly reduced the incidence of these symptoms in sea bass, increasing the tissue content in several PUFA and improving growth and stress resistance. Moreover, when sea bass was fed diets containing high vitamin E levels, fish showed a significant improvement in growth when dietary DHA was raised from 1% to 3%. Therefore, in sea bass larvae, a ratio of 30 g kg−1 DHA and 3000 mg kg−1 vitamin E seems to be adequate to achieve a good larval performance and to avoid muscular lesions.

Effects of dietary lipid levels on growth, feed utilization, body composition, fatty acid profiles and antioxidant parameters of juvenile chu’s croaker Nibea coibor

“…Although lipid intake and lipid gain increased with the increase in dietary lipids, the low LRE, an indicator of poor lipid retention, showed by fish fed with D15 follows the same trend of teleost pejerrey Odontesthes bonariensis, when fed lipid levels higher than 25 % (Gómez-Requeni et al 2013). Betancor et al (2011) reported that HUFA (mainly DHA) was readily deposited in fish tissues and associated with higher sea bass mortalities because of increased peroxidation risks, and dietary DHA contents up to 5 % severely increased the incidence of muscular lesions and the presence of ceroid pigment within hepatocytes. Therefore, the reduced fatty acid absorption efficiency and ultimately juvenile growth might be because of high dietary levels of HUFA levels (such as 20:5n-3, 22:5n-3 and 22:6n-3) which are highly susceptible to being oxidized and triggering in vivo oxidative stress in the test fish.…”

Fish larval nutrition and feed formulation: knowledge gaps and bottlenecks for advances in larval rearing

“…(2008) used 1.5 and 3.0 g kg −1 dry diet of α‐TOH for gilthead seabream and sea bass, and suggested an optimal level of 3 g kg −1 because this high level reduced mortality after stress, but not the mortality under standard rearing conditions. In the same study, the high α‐TOH level also alleviated muscular lesions caused by excessive dietary DHA (Betancor et al. 2011).…”

Oxidative status and histological changes in sea bass larvae muscle in response to high dietary content of docosahexaenoic acid DHA

“…Moreover, the increase in dietary levels of vitamin E reduced the incidence of these muscular lesions (Betancor et al . ). However, this beneficial effect of vitamin E was not observed in this study when 5% of DHA was included in the diet, suggesting that the addition of vitamin E alone as an antioxidant is not enough to control lipid peroxidation when high levels of DHA are included in fish larvae diets.…”

“…In a previous study, an increase in the incidence of muscle lesions was observed in sea bass larvae, Dicentrarchus labrax (L.), fed increasing levels of DHA, particularly when vitamin E levels were low (Betancor et al . ) Several reasons may explain the higher susceptibility of muscular tissues to free radical injury. For instance, muscle is prone to oxidative injury as a result of increased electron flux because of its requirement and ability to undertake rapid and coordinated changes in energy supply and oxygen flux during contraction (Haycock et al .…”