Effects of dietary oxidized lipid and vitamin A on the early development and antioxidant status of Siberian sturgeon (Acipenser baeri) larvae

Abstract

A 4-week feeding trial was conducted to investigate the effects of dietary oxidized lipid and vitamin A on the early ontogenesis and the antioxidant status of Siberian sturgeon larvae. Auto-oxidized capelin oil (peroxide value=245meq/kg) was added at 3 levels: 0, 40 and 80g/kg in semi-purified casein based diets containing either 22,500 or 772,500IU/kg vitamin A as retinyl acetate.Survival and growth were significantly reduced in larvae fed diets containing oxidized lipid with the lowest vitamin A level. A high percentage (25%) of deformed larvae was noted with diets containing 80g/kg oxidized lipid. These effects were not observed in larvae fed diets with higher vitamin A level indicating an interaction between dietary oxidized lipid and vitamin A. The highest dietary vitamin A level had negative effects in larvae fed fresh lipid and positive effects in larvae fed oxidized lipid, compared to the lowest supply of vitamin A.Retinyl palmitate was found to be the main storage form of vitamin A with 6.7μg/g in larvae fed diets with the highest vitamin A level and only 0.05μg/g in larvae fed diets with the lowest vitamin A level, irrespective of the dietary oxidized lipid level. Retinol contents in larvae were also significantly affected by dietary vitamin A level. Retinoid levels in larval bodies were not modified by dietary oxidized lipid level. Indicators of lipid peroxidation in larvae such as 8-isoprostanes were the highest in larvae fed 80g oxidized lipid/kg diet as activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase poorly respond to dietary oxidized lipid and vitamin A.An increased oxidative stress in Siberian sturgeon larvae fed oxidized lipid may account for their poor growth and survival and high occurrence of deformed fish. A high dietary supplementation with vitamin A allowed to counteract partially the negative effects of dietary oxidized lipid, suggesting antioxidant properties of dietary vitamin A. However the precise role of dietary vitamin A on negative effects due to oxidized lipid in Siberian sturgeon larvae remains unclear.