Interactive effect of dietary vitamin E and inorganic mercury on growth performance and bioaccumulation of mercury in juvenile olive flounder, Paralichthys olivaceus treated with mercuric chloride

Abstract

A 6-week feeding trial was carried out to evaluate the effects of dietary vitamin E (dl-α-tocopheryl acetate, TA) on growth and mercury (Hg) accumulation in juvenile olive flounder (Paralichthys olivaceus) treated with mercuric chloride (HgCl2). Vitamin E and HgCl2 were added to the semi-purified basal diet. Six semi-purified diets in a 2 × 3 factorial design were formulated to contain 2 levels of Hg (0 or 20 mg HgCl2/kg diet) and 3 levels of vitamin E (0, 100, or 200 mg TA/kg diet). Experimental fish (n = 360, 9.99 ± 0.15 g) were randomly allocated into 30-L tanks at a density of 20 fish per tank with 3 replicates in each treatment and were fed twice a day. At the end of the feeding trial, dietary Hg depressed the growth performances in terms of weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) in fish, while fish fed the diets supplemented with vitamin E showed significant growth improvement in both presence and absence of HgCl2 in the diets (P < 0.05). Survival rate was not affected in fish fed the experimental diets. Whole body compositions of fish such as lipid and moisture contents were influenced by dietary vitamin E supplementation. Total Hg contents of muscle, liver and kidney tissues were significantly reduced in fish fed diets supplemented with vitamin E (P < 0.05), while the two-way ANOVA showed that increasing Hg concentration has resulted in a reduction in vitamin E. Whole body fatty acids of fish like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents were decreased by dietary Hg. However, supplementation of dietary vitamin E improved the α-linolenic acid (ALA) and EPA contents in fish. Our results suggest that dietary supplementation of vitamin E has potential effects on growth improvement and ameliorating inorganic Hg bioaccumulation in juvenile olive flounder.

Protective Role of Dietary Vitamin E Against Oxidative Stress Induced by Copper Sulphate in Nile Tilapia (Oreochromis Niloticus)

“…Supplementation of dietary vitamin E improved whole-body fatty acids of fish like the a-linolenic acid (ALA) and eicosapentaenoic acid (EPA) contents in fish. On the other hand, dietary supplementation of vitamin E (100 or 200 mg/kg diet) can enhance the growth performance in juvenile olive flounder intoxicated with mercury (Moniruzzaman et al, 2017). The present results recorded improved growth performance with the addition of the antioxidant (Vit E) and that could have potential use as a preventive or therapeutic measure in Cu-exposed fish.…”

Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species

“…Bloom () also assessed the relationship between %MeHg and lipid content of fish muscle and found no relationship, despite a 25‐fold difference in lipid estimates across samples. Nevertheless, further studies could consider higher lipid content fish (i.e., C:N > 5), as well as other factors that affect Hg speciation in fish muscle such as selenium (Bjerregaard et al ) or vitamin E content (Moniruzzaman et al ).…”

Toxic Effects of Mercuric Chloride (HgCl2) on the Common Carp (Cyprinus carpio) Larvae and Recovery Using Selenium and Vitamins

“…Therefore, treatment with selenium as well as vitamins E and C was used to protect and retrieve these larvae from HgCl 2 intoxication, considering nutritional perspectives as stated by Clarkson (1998) and Moniruzzaman et al (2017).…”