Synergistic Effects of Dietary Vitamin C, E and Selenomethionine on Growth Performance, Tissue Mercury Content and Oxidative Biomarkers of Juvenile Olive Flounder,Paralichthys olivaceus(Temminck & Schlegel) Toxified with the High Dietary Methylmercury

Abstract

A 10-week feeding trial was conducted to evaluate the tissue level synergistic effects of dietary vitamin C, E and selenomethionine (SeMet) on dietary methylmercury (MeHg) toxicity in juvenile olive flounder, Paralichthys olivaceus. Eight semi-purified diets were formulated to contain two different vitamin C levels as L-ascorbyl-2-monophosphate (400 and 800 mg AMP/kg diet), two vitamin E levels as DL-α-tocopheryl acetate (100 and 200 mg TA/kg diet) and two selenium (Se) levels as selenomethionine (2 and 4 mg SeMet/kgdiet) on the constant mercury (Hg) level (20 mg MeHg/kgdiet). Eight experimental diets, in a 2×2×2 factorial design (C400E100Se2, C400E100Se4, C400E200Se2, C400E200Se4, C800E100Se2, C800E100Se4, C800E200Se2 and C800E200Se4) were fed to triplicate group of fishes averaging 3.12±0.04g (mean±SD) in the semi-recirculation system. After 10 weeks of feeding trial, weight gain (WG) offish fed diets containing C400E200Se4, C800E100Se2 and C800E200Se2 were significantly higher than those of fish fed diets containing C400E100Se2 and C400E100Se4 (P<0.05). Feed efficiency (FE), specific growth rate (SGR), protein efficiency ratio (PER) showed a similar trend as WG. The most significant depleting trend of mercury accumulation was found in kidney tissue. Tissue oxidative biomarkers like superoxide dismutase (SOD) and thiobarbituric acid reactive substances (TBARS) in liver and kidney tissues improved up to higher levels of vitamin C, E and Se. Therefore, these findings indicated that the best combinations of dietary antioxidant levels could be C400E200Se4 or C800E200Se2 diet based on WG by analysis of variance (ANOVA) test in terms of reducing tissue MeHg content in juvenile olive flounder.