Effects of different lipid sources on growth performance, fatty acids composition in tissue and expression of genes related to lipid metabolism in largemouth bass (Micropterus salmoides)

Abstract

An eight-week feeding trial was conducted to investigate the effects of dietary lipid sources on growth performance, fatty acids composition in tissue and expression of genes related to lipid metabolism in juvenile largemouth bass (Micropterus salmoides). Four experimental diets were formulated to contain 6% coconut oil (CO), rapeseed oil (RO), linseed oil (LO) and fish oil (FO), respectively. Each diet was fed to triplicate groups of juvenile for 8 weeks. The results indicated that final body weight (FBW), percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), survival, hepatopancreas index (HSI), viscerosomatic index (VSI) and intraperitoneal fat ratio (IPF) were not significantly influenced by dietary different lipid sources (P＞0.05). Moreover, proximate composition in whole body, dorsal muscle and liver were also not significantly affected by dietary different lipid sources (P ＞0.05). Fish fed with FO diet was significantly higher MDA concentration in hepatic and serum than those fed with CO, RO and LO diets (P < 0.05). However, T-AOC, SOD and GSH activities in hepatic and serum were not affected by different lipid sources (P＞0.05). Fish fed with RO diet had significantly higher relative expression of fas and acc in liver than those fed the other diets, the highest expression of lpl was occurred at fish fed with CO diet (p < 0.05). Meanwhile, fish fed with CO and FO diets had significantly lower expression of elovl5 and Δ6fad in liver than those fed with RO diet (p < 0.05). In conclusion, the results of present study indicated that vegetable oils such as CO, RO and LO can potentially be used as dietary FO substitutes for juvenile largemouth bass.