Effects of different vegetable oil sources on growth performance, body composition and tissue fatty acid composition of spotted knifejaw, Oplegnathus punctatus

During 8-weeks feeding trial, four experimental diets were designed to assess the effects of different lipid sources, including fish oil (FO), soybean oil (SO), rapeseed oil (RO) and linseed oil (LO) on growth performance, body composition and tissue fatty acid composition of Oplegnathus punctatus. Each diet was fed to triplicate groups (initial body weight 12.06 ± 0.09 g per fish). The weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) of fish fed LO diets were not significantly different from those fed FO diets, but significantly higher than those fed SO and RO diets. Besides, although the contents of EPA or DHA in different vegetable oil diets were same, the EPA content in muscle and liver and DHA content in liver of the LO group were significantly higher than that of the SO and RO groups. In addition, the highest gene expression of fads2 presented in fish fed LO diets, whereas the gene expression of elovl5 was not significantly different in three vegetable oil groups. Fish fed the SO diet had the highest liver lipid content, hepatosomatic index (HSI), viscerosomatic index (VSI), aspartate transaminase (AST) and alanine transaminase (ALT) values. In conclusion, under experimental conditions, the complete substitution of LO for FO had not negative effect on the feed utilization and growth performance of O.punctatus