Effects of dietary lipid levels on lipid deposition and activities of lipid metabolic enzymes in hybrid tilapia (Oreochromis niloticus × O. aureus)

Abstract

This study was designed to investigate the effects of dietary lipid levels on growth performance, lipid deposition and activities of lipid metabolic enzymes in hybrid tilapia (Oreochromis niloticus × O. aureus). Four isonitrogenous (300 g/kg crude protein) experimental diets containing graded levels of lipid (25, 55, 85 and 115 g/kg) were randomly assigned to triplicate groups of 180 juvenile fish. Fish were fed twice daily for 8 weeks. At the end of the experiment, the growth performance and proximate composition of fish were determined. The activities and gene expression of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) were assessed as well. Fish fed the diets with 55 and 85 g/kg lipid had a significantly (p < 0.05) higher body weight gain than those fed the diets with 25 and 115 g/kg lipid. The whole-body and liver lipid contents were significantly (p < 0.05) elevated with increasing dietary lipid levels. Moreover, the activities and mRNA abundances of LPL and HSL in the liver, dorsal muscle and fat tissues were markedly altered by dietary lipid levels. Our data demonstrate a profound influence of dietary lipid levels on the growth and lipid deposition in hybrid tilapia, which is likely associated with the regulation of lipid metabolic enzymes including LPL and HSL.