Study On Choline Requirement Of The Commercial Laving Hens In Low Energy Diets

The three experiments were conducted to study the influence of dietarycholine levels on the laying performance，egg quality，as well as lipid metabolism incommercial Hy-line laying hens.Experiment1：Effects of different choline levels on laying performance in low energydiets.A total of eight hundred and ten Hy-line brown hens aged24weeks wererandomly divided into six group with five replicates per group and27laying hens perreplicate. The diet was based on corn-soybean meal, energy was10.89MJ/Kg（2600Kcal/Kg）.The contents of choline and methionine in the basal diet were1116mg/kg and0.34%respectively. Then the hens supplied with0,100,300.500.700mg/kg choline on basis of basal diets. The control group wasdesigned according to GB(2004).The results showed that: there was no significanteffect on the laying rates in the peak stage（P＞0.05）when the supplement of cholinevaried from0to700mg/kg.According to the laying performance and economicefficiency, the optimum dosage of choline was300mg/kg.Experiment2：Effects of different choline levels on egg quality in low energy dietsThe experiment was conducted to research the effects of different choline levelson conventional quality and nutritional composition of egg in low energy diets. At theend of feeding experiment, five eggs were collected randomly from each replicate tomeasure egg quality. The results showed that: there was no significant effect onconventional egg quality and the water content of egg in the peak stage（P＞0.05）when the supplement of choline varied from0to700mg/kg;for the crude fat contentof egg, adding700mg/kg choline group was numerically higher than no choline group,the difference was significan（tP＜0.05）, and there were no significant difference withthe other treatment groups (P>0.05).The analysis indicated that different cholinelevels had no effect on egg quality.Experiment3：Effects of different choline levels on lipid metabolism in low energydietsThe experiment was conducted to research the effects of different choline levelson lipid metabolism of laying hens in low energy diets. One layer was selected in each repeat on the last day of the experiment, watered fasted12h and sampled blood fromwing vein, then prepared serum centrifugal and slaughtered for taking liver andabdominal fat. Test results showed that:①Increasing choline levels in the diets resultsin decline in fattiness in liver（P＜0.05）；there was trend to decrease liver index andpercentage of abdominal fat， but the difference was not significant （P＞0.05）.②Increasing choline levels in the diets results in improvement of serum TGlevels, the difference was significant in adding500mg/kg choline group（P＜0.05）;choline supplementation did not change serum T-CHO,HDL-C and LDL-C（P＞0.05）.③Increasing choline levels in the diets results in improvement of serum LPSactivity, adding300-700mg/kg choline group was numerically higher than the controlgroup（P＜0.05）;there was trend to decrease CHE and ALP activities with theincrease of choline，but the difference was not significant（P＞0.05）;increasingcholine levels in the diets results in decline in serum ALT and AST activities（P＜0.05）,serum ALT activities of all treatments were extremely lower than the controlgroup（P＜0.01）,serum AST activity of adding300mg/kg choline group wasnumerically lower than the control group（P＜0.05）.According to the liver and bloodbiochemical indexes of layer, the optimum dosage of choline was300-500mg/kg.