Effect Of Methionine Hydroxy Agalog Chelated Zinc On Production Performance,Blood Biochemical Index And Liver Metabolism Of Laying Hens

Trace element zinc widely used in livestock and poultry breeding,however more attentions focused on the waste and environmental pollution by the low absorption rate of zinc in animal body.Our previous studies showed that the deposition rate of organic zinc in the tibia and tissues was higher than that of inorganic zinc,whereas the molecular mechanism of organic zinc metabolism was not clear.In this study,we adopted metabolomics to explore the metabolic mechanism of organic zinc in the body by combining the apparent production performance and blood biochemical indexes in laying hens.Exp.1 Effects of methionine hydroxyl analog chelated zinc on production performance and egg quality of laying hensThe aim of this study was to investigate the effect of zinc chelated product(MHA-Zn)on the performance and quality of laying hens.Nine hundred and sixty laying hens were randomly divided into 4 groups.Based on the national standard NY/ T33-2004 and NRC(1994)and combined with the management manual of Hy-Line laying hens,corn-soybean meal basic diet(zinc content 35.08 mg/kg)was prepared.In the control group,80 mg/kg zinc sulfate added to the basic diet.In the experimental group,20,40 and 80 mg/kg MHA-Zn(organic zinc)added to the basic diet.The period of trial test was 4 weeks and the test period was 12 weeks.The results showed that: 1)there was no significant difference between organic zinc and inorganic zinc in laying rate,average egg weight,average daily intake,material to egg ratio and daily egg weight.2)There was no significant difference in the height of egg protein,haugh unit and yolk color between the groups(P > 0.05).The eggshell thickness and strength of laying hens in the 40 and 80 mg/kg MHA-Zn groups were significantly higher than those indexes in the control group and the 20 mg/kg MHA-Zn group(P < 0.05).The egg broken rate was significantly lower than the control group and the 20 mg/ kg MHA-Zn group(P < 0.05).Therefore,the addition of 40 and 80 mg/kg MHA-Zn in the feed can significantly improve the thickness and strength of the eggshell,and significantly reduce egg broken rate.Exp.2 Effects of methionine hydroxyl analog chelated zinc on serum biochemical and immune indices of laying hensExperiment design of Exp.2 was similar with Exp.1.The result showed that: 1)the serum level of GPT in the 20 mg/kg MHA-Zn group increased significantly,while the level of GPT in the 80 mg/kg MHA-Zn group decreased significantly(P < 0.05).The level of SGOT also showed this trend,but was not significant(P >0.05).Total protein levels were significantly increased in the 40 and 80 mg/ kg MHA-Zn groups(P < 0.05),and serum globulin levels were significantly increased in the 40 mg/kg MHA-Zn group(P < 0.05).2)there was no significant difference in the relative expression levels of tumor necrosis factor-(TNF-),interleukin-10(IL-10)and nuclear factor-KB1(NF-KB1)mRNA between layers(P > 0.05).The relative expression of interleukin-8(il-8)mRNA in 80 mg/kg MHA-Zn group was significantly lower than that in 40 mg/kg MHA-Zn group(P < 0.05).Exp.3 Effects of methionine hydroxyl analog chelated zinc on liver metabolites of laying hensExperiment design of Exp.3 was similar with Exp.1.NMR metabolomics combined with the biochemical indexes was applied to chicken liver samples of laying hens at the later stage.The experimental design is the same as above.Principal component analysis(PCA)and partial least square NMR spectral analysis model(PLS-DA)used for tracking,and T-test was used to detect the significant difference of metabolites.The results showed that : 1)PCA and(PLSDA)models of 40 and 80 mg/kg MHA-Zn and inorganic zinc groups had better verification results.2)The T test and analysis results of(PLS-DA)model showed that 20 mg/kg MHA-Zn group compared with inorganic zinc group,the metabolites of taurine and malic acid significantly reduced.In 40 mg/kg MHA-Zn group,serine and threonine increased significantly,80 mg/kg MHA-Zn compared with inorganic zinc group,acetic acid,uridine,phosphoric acid,choline and cysteine metabolites significantly reduced(P < 0.05).3)KEGG metabolic pathway analysis performed on 40 and 80 mg/kg MHA-Zn group compared with the control group using the original chicken as the model organism.Pathway analysis showed that pyruvate,choline,and l-phosphocholine concentrations were down-regulated,indicating that MHA-Zn was involved in inhibiting lipid metabolism.The concentrations of serine,threonine and betaine were significantly up-regulated.Combined with biochemical indexes,MHA-Zn regulates the synthesis of antioxidant enzymes in the body,participates in lipid metabolism and balance energy metabolism,and participates in pyrimidine synthesis.This discovery helps to elucidate the potential mechanism of zinc nutrition and metabolism in diets of elderly laying hens.Conclusions:(1)The thickness and strength of the eggshell improved in 40 and 80 mg/kg MHA-Zn groups of laying hens and the broken egg rate reduced.(2)The level of total protein and globulin in serum increased in 40 mg/kg MHA-Zn group of laying hens,and 80 mg/kg MHA-Zn group could reduce the level of glutamate transaminase and increase the content of urea,and the content of triglyceride decreased with the increase of organic zinc.(3)Compared with control group,the 40 and 80 mg/kg MHA-Zn groups screened for 10 different metabolic pathways enriched with metabolites,and the metabolism of glycine,serine and threonine,d-glutamine and d-glutamate in the metabolic pathways specifically analyzed.The increase of threonine levels in the 40 and 80 mg/kg MHA-Zn groups may related to the involvement of organic zinc in the immune response.The content of choline and choline phosphate in the metabolites decreased,while the content of betaine increased.MHA-Zn is involved in lipid metabolism in liver metabolism and inhibits fat synthesis.The metabolic changes of serine,threonine,glutamine,glycine and pyruvate indicated that organic zinc was involved in sugar metabolism and promoting amino acid metabolism and pyrimidine nucleotides.