Effects of dietary choline on growth performance, lipid deposition and hepatic lipid transport of grouper (Epinephelus coioides)

The number of 360 individuals with an average initial weight of 87.8 +/- 0.04 g was fed six diets containing graded levels of choline at 8.1 (control group), 602.5, 1119.0, 1511.5, 1970.0 and 4029.0 mg choline kg(-1) diet, respectively, to investigate the effects of dietary choline on growth performance, lipid deposition and hepatic lipid transport for grouper, Epinephelus coioides. Dietary methionine was estimated to be 10.02 g kg(-1), less than the requirement (13.10 g kg(-1)). The results of 10-week study period indicated that the best values of specific growth rate (SGR), feed conversion rate (FCR) and protein efficiency rate (PER) all occurred in 1119.0 mg choline kg(-1) diet (P < 0.05). The survival range increased from 8.1 to 1511.5 mg choline kg(-1) diet and then plateaued. Dietary choline supplementation significantly decreased the liver lipid content of grouper (P < 0.05), but the lipid content of the muscle tended to be increased firstly and then decreased (P < 0.05). Liver choline concentration reached a plateau in 1511.5 mg choline kg(-1) diet and then levelled off (P < 0.05). Serum high density lipoprotein-cholesterol (HDL-C) and total cholesterol (TCHO) levels were firstly decreased and then increased with dietary choline supplementation. A reversed tendency, however, was found in triglyceride. Broken-line regression analysis of SGR and liver choline content indicated that choline requirement of grouper was 1093.7 and 1579.7 mg kg(-1) diet, respectively.