Effects of dietary lipid sources on growth performance, fatty acid composition and hepatic lipid metabolism of juvenile blunt snout bream, Megalobrama amblycephala

This study investigated the effects of dietary lipid sources on juvenile blunt snout bream, Megalobrama amblycephala. Juvenile blunt snout bream (14.40 +/- 0.01 g) were fed diets containing 75 g/kg of fish oil (FO), linseed oil (LO), soybean oil, coconut oil (CO), rapeseed oil or beef tallow (BT) for 9 weeks. Survival rates, final weight, weight gain, feed efficiency ratio and feed intake remained unchanged. Viscerosomatic ratio, hepatosomatic index and condition factor were highest in fish fed the CO diet (p < 0.05). Whole-body lipid content decreased, whereas liver lipid content increased in fish fed CO and BT diets (p < 0.05). Eicosapentaenoic acid and docosahexaenoic acid in the muscle and liver increased in fish fed the FO and LO diets (p < 0.05). FO and LO diets increased plasma glucose (p < 0.05). Feeding CO diet increased hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase expression, and FAS activity (p < 0.05). Both CO and BT diets increased hepatic carnitine palmitoyltransferase I (CPT I) and carnitine palmitoyltransferase II expression, and CPT I activity compared to the FO diet (p < 0.05). These results indicate that LO can be substituted for FO in juvenile blunt snout bream diets without negative effects.