Evaluation On Relative Bioavailability And Requirement Of Choline In Juvenile Blunt Snout Bream, Megalobrama Amblycephala

This study was conducted to determine the Dietary choline requirement and utilization of choline in differene levels and dietary choline availability values in seven common feed ingredients for juvenile blunt snout bream, Megalobrama amblycephala, in order to provide theoretical basis for optimizing the formula for this species. This study includer twoexperiments:Experiment1Dietary choline requirement for juvenile blunt snout bream, Megalobrama amblycephalaA12-week feeding trial was conducted to determine dietary choline requirement for juvenile Megalobrama amblycephala. This premix provided methionine at7.5g/kg, slightly less than the optimal requirement of Megalobrama amblycephala (7.9g/kg), so endogenous synthesis of choline from methionine would be limited. Choline chloride was supplemented to the basal diet to formulate six purified diets containing0,250,500,1000,2000and4000mg/kg, respectively. Each diet was randomly fed to quadrupled groups of Megalobrama amblycephala with initial average weight1.84±0.04g 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 increasing (P<0.01), whereas, lipid content of dressed carcass showed opposite trend (P<0.01), and lipid content of whole-body is unacted on dietary choline supplementation. Broke line regression of weight gain, liver and muscle choline concentration showed choline requirements of Megalobrama amblycephala is1198,1525and1365mg/kg, respectively. In addition, dietary choline supplementation significantly improved whole body lipid distribution but not content of blunt snout bream. Experiment2Utilization of choline in differene levels and dietary choline availability values in seven common feed ingredients for juvenile blunt snout bream, Megalobrama amblycephalaAn8-week feeding trial was conducted to evaluate dietary choline availability values in seven common feed ingredients for juvenile blunt snout bream Megalobrama amblycephala. The basal diet was formulated to contain310g/kg diet from vitamin-free casein and gelatin. Choline chloride was supplemented to the basal diet to formulate four purified diets containing0,1030,1230and1430mg/kg, respectively. These four purified diets were used to generate a standard curve for determining the choline availability in seven test diets containing the following common feed ingredients, fish meal (FM), soybean meal (SBM), rapeseed meal (RSM), cottonseed meal (CSM), wheat middling (WM), wheat bran (WB) and rice bran (RB). The choline in seven test dites was1230mg/kg which1030mg/kg was supplemented by choline chloride and the other was come from feed ingredients, accordingly. Each diet was randomly fed to three groups of Megalobrama amblycephala with initial average weight (3.5±0.1) g in a flow-through system. Results showed weight gain and liver choline concentration were increased significantly with increasing dietary choline levels (P<0.05) in first four tests; The weight gain was increased more quickly then the third test. Based on liver choline data, choline availability values were87.42,112.54,76.84,98,95.91,43.88and91.5%in FM, SBM, RSM, CSM, WM, WB and RB, respectively. In addition, choline chloride should be supplemented in feeds, and the levels of choline chloride are depended on species of ingredients.