Effects Of Methionine Chelate Zinc On Production Performance,Egg Quality Andimmune Function Of Aged Laying Hens

For laying hens,due to the strong lipid metabolism for a long time in the late laying period,the body’s reproductive system and antioxidant state significantly decreased,eggs become bigger,egg weight increased,egg shell quality deterioration.As an indispensable trace element in the diet of laying hens,zinc plays an important role in the production.Compared with the inorganic source,organic zinc can reduce the chelating effect in the intestine,the interaction between the metal ions,enhance the stability of trace elements at low pH,and promte the absorption and utilization rate,so it is gradually applied to poultry diet.The effects of different levels of zinc methionine chelate(MHA-Zn)on the production performance,egg quality and immune performance of laying hens in laying hens were studied in this study.A total of 960 Hyline variety brownlaying hens aged 56 weeks were randomly divided into 4 groups per group with 8 replicates and 30 hens per replicate.According to the standard of Chinese laying hens(NY / T 33-2004)with Hailan company recommended diet nutrition level,to design a corn-soybean meal basal diet.These diets consisted of the basal diet supplemented with 80 mg/kg zinc sulfate(control group),20,40 and 80 mg/kg NHA-Zn(tested groups).Pre-feeding period of 2 weeks,trial period of 14 weeks,regular feeding and management.Theproduction performance,egg quality and immune function were measured.1.Effects of MHA-Zn on production performance and egg quality of aged laying hens(1)Compared to control group,dietary supplementation with 20,40 and 80 mg/kg MHA-Zn had no significant difference on laying rate,feed intake rate and other indexes of laying performance(P>0.05).No significant differences were found on egg shape index,albumen height,yolk color,yolk weight percent,haught unit(P>0.05).However,groups with organic zinc significantly reduced layer mortality rate.(2)Compared to control group,group with 40 and 80 mg/kg MHA-Zn could greatly improve eggshell thickness,eggshell strength,eggshell weight percent and eggshell density,reduced broken eggshell rate(P<0.05).2.Effects of zinc methionine chelate on immune function in laying hensDietary supplementation with 40,80 mg / kg of MHA-Zn could significantly improve the thymus index of laying hens(P<0.05),but had no significant effect on the level of immunoglobulin in serum(P>0.05).At the level,H5 antibody in avian influenza was significantly increased(P<0.05),and the decline tendency of H5 and ND antibody could be delayed.In conclusion:(1)Dietary supplementation with MHA-Zn had no significant effect on the production performance of the laying hens,but it could reduce the mortality and improve the eggshell quality.This effect is related to the high absorption and utilization rate of organic zinc.(2)Dietary supplementation with MHA-Zn could improve thymus index,the level of H5 antibody in serum,delay the decline trend of ND antibody,IgG and IgM.