Effects of dietary supplementation with coconut oil on the growth, fatty acid profiles and some lipid metabolism relative gene expressions of orange-spotted grouper Epinephelus coioides

Abstract

This study investigated the effects of coconut oil as a dietary supplement on the growth, lipid metabolism and related gene expressions of juvenile orange-spotted grouper Epinephelus coioides. Coconut oil at concentrations of 0, 10, 30 and 50 g/kg was used to replace dietary lipids in a basal diet containing 150 g/kg lipids. The four experimental diets were, respectively, fed to triplicate groups of juvenile groupers (initial weight: 8.53 +/- 0.13 g) in a recirculating system for 8 weeks. Fish fed the diet containing 50 g/kg coconut oil exhibited lower (p < .05) weight gain than did fish fed the diet containing 30 g/kg coconut oil; however, no significant differences in weight gain were observed between fish fed diets containing 0 and 10 g/kg coconut oil. Hepatic carnitine palmitoyltransferase-1, fatty acid synthase, fatty acid elongase, fatty acid desaturase and peroxisome proliferator-activated receptor gamma gene expressions were all the highest in fish fed the diet containing 10 g/kg coconut oil. Fish fed the coconut oil-free basal diet demonstrated upregulated gene expression of neuropeptide Y. The results suggest that dietary supplementation with 10 g/kg coconut oil exerted beneficial effects on lipid metabolism by E. coioides.