Regulation of growth, tissue fatty acid composition, biochemical parameters and lipid related genes expression by different dietary lipid sources in juvenile black seabream, Acanthopagrus schlegelii

Abstract

The effects of different dietary lipid sources on physiological characteristics and lipid metabolism relevant genes expression were assessed in juvenile black seabream Acanthopagrus schlegelii. 720 black seabream juveniles (initial weight was 5.4±0.0g) were randomly allocated in 18 floating net cages corresponding to triplicate cages of the six dietary treatments, and the 8-week feeding trail was conducted. Five isonitrogenus and isolipidic diets were formulated to contain lipid sources: coconut oil (CO), perilla oil (PO), sunflower oil (SO), arachidonic acid (ARA) and eicosapentaenoic acid combined with docosahexaenoic acid (EPA+DHA), and fish oil (FO) was set as a control group. The results showed that weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) in fish fed diets containing FO and EPA+DHA were significantly higher than CO. In serum, the highest activity of glutathione peroxidase (GSH-PX) and glutathione (GSH) content were recorded in fish fed EPA+DHA. The significantly highest content of malondialdehyde (MDA) was observed in fish fed the EPA+DHA and FO diets. The maximum hepatic content of MDA and the minimum activity of superoxide dismutase (SOD) were all found in fish fed the diet containing EPA+DHA. High contents of cholesterol (CHOL) and triacylglycerol (TAG) were found in fish fed SO, whereas glucose (GLU) content in fish fed EPA+DHA was significantly higher than in the other treatments. Fish fed FO had the highest hemoglobin (HGB) among treatments. The anabolic pathway relevant genes: accα, fas and srebp-1 were up-regulated by dietary SO and PO. Whereas, the catabolic pathway relevant genes: lpl, cpt1a, atgl, hsl and pparα were down-regulated by dietary CO. Furthermore, the long chain polyunsaturated fatty acid (LC-PUFA) biosynthesis relevant genes elovl5 and fads2 were significantly up-regulated by dietary SO and PO. The present study focused on comparing the effects of different dietary lipid sources on biochemical characteristics and lipid metabolism relevant genes expression in black seabream. Overall, it demonstrated that physiological-biochemical characteristics as well as lipid metabolism relevant genes expression were significantly regulated by different dietary lipid sources. Moreover, dietary PO and SO regulated some physiological and biochemical indicators. These findings could contribute to optimize aquatic feeds when considering selection of optimal lipid sources or their optimal proportion in the future.