Dietary choline requirement for juvenile blunt snout bream,Megalobrama amblycephala

A 12-week feeding trial was conducted to determine dietary choline requirement for juvenile Megalobrama amblycephala. The basal diet was formulated to contain 310 g kg−1 diet from vitamin-free casein and gelatine. Choline chloride was supplemented to the basal diet to formulate six purified diets containing 0, 250, 500, 1000, 2000 and 4000 mg kg−1, respectively. Each diet was randomly fed to quadrupled groups of Megalobrama amblycephala with initial average weight 1.84 ± 0.04 g in a flow-through system. Results showed weight gain was increased significantly with increasing dietary choline levels (P < 0.01). Lipid content of liver decreased significantly as dietary choline concentration increased (P < 0.01), whereas lipid content of dressed carcass showed opposite trend (P < 0.01), and lipid content of whole-body was unaffected by dietary choline supplementation. Broken- line regression of weight gain, liver and muscle choline concentration showed choline requirements of Megalobrama amblycephala of 1198, 1525 and 1365 mg kg−1, respectively. In addition, dietary choline supplementation significantly improved lipid content of dressed carcass but not the content of whole body of blunt snout bream.