Suplementação dietética de óleos vegetais e selênio para corvina (Argyrosomus regius)

Abstract

Vegetable oils are the alternative source to marine fish oils in aquaculture feeds. Nonetheless, since a single source of vegetable oil doesn't have the appropriate fatty acid composition as do marine fish diets, a blend of vegetable oils can be a solution to aquaculture feeds. Selenium is an essential micro-mineral in aquatic organisms’ diets and is a co-factor of glutathione peroxidase, an antioxidant enzyme. Thus aimed to evaluate the effect of supplementation of vegetable oils and selenium in the meagre diet. Meagre with initial weight of 20.45 ± 1.4 g were distributed in a recirculation system consisting of 24 experimental units of 80 liters at a density of 25 fish per tank. To maintain water quality, the system was equipped with mechanical filter, biological, ultraviolet and skimmer. The fish were fed with eight experimental diets which were composed of two lipid sources (fish oil or vegetable oil), two lipid levels (12 and 17%) with or without added selenium. During the test the water temperature was 20.7 ± 0.7 ° C, oxygen 8.8 ± 1.7 mg L-1 and Salinity 28.3 ± 2.1 ppt. The parameters analyzed were: animal performance, immunology, digestive capacity, histology, biomarkers of oxidative stress, chemical composition and muscle and liver fatty acids deposition. Meagre fed with fish oil showed higher final weight, weight gain and specific growth rate and better feed conversion than those fish fed with vegetable oil. In addition, diets containing 12% lipids including increased weight gain and fish specific growth rate. The activity of lysozyme and peroxidase were higher in fish fed with vegetable oil. In contrast, the complement system was more active in meagre fed with fish oils. Regarding oxidative stress biomarkers, it was found that the catalase activity increased with feeding diets containing 17% fish oil 12% compared to the same source. Already glutathione peroxidase activity increased when diets were composed of selenium. As liver and muscle fatty acids deposition, it was found that meagre possess the ability to elongase and desaturate fatty acids with more than 20 carbons from their 18-carbon precursors. It is recommended to add meagre diets comprised of 12% fish oil.