Effects Of Threonine Levels On Broilers Intestinal Based On Transcriptology And Metabomics

As the third restricted amino acid in poultry,threonine plays an important role in regulating its immunity and antioxidant performance.The deep mechanism of improving intestinal antioxidant performance of poultry is not clear.This experiment was conducted to evaluate the effect of different dietary threonine levels on the antioxidant and immunity of broilers,and to provide evidence for the application of threonine in broiler production.A total of 432 one–day-old AA broilers were randomly allocated to 4 dietary treatments with 6 replicates of 18 broilers.The amount of dietary threonine in four treatments(T1 to T4)reached 85%,100%,125%,and 150% of NRC recommendation for broilers,respectively.After 42 days of feeding experiment,cecum contents and jejunum mucosa were collected for metabolic analysis and transcriptional sequencin.The results showed that:(1)The dietary threonine level 125% of the recommended standard for dietary threonine,the profile of different metabolism was the most significant compared with the recommended level of threonine.The level of threonine 85% and 150% of the recommended standard of NRC(1994).The area of different metabolic profile was very small;(2)The dietary threonine level 125% of the recommended standard for dietary threonine,compared with the standard recommended amount 100%,the significantly different metabolites were glutamate,acetate,proplonate,ethanol,butyrate,valeate,respectively;(3)The dietary threonine level 125% of the recommended standard for dietary threonine,a total of 135 pathways,465 up-regulated genes and 331 down-regulated genes were involved in the KEGG database of 796 differentially expressed genes;(4)All the pathways involved in the six different metabolites in the metabolic group test results were found by using the KEGG library.There were 12 pathways shared by the two groups,of which 36 were differentially expressed genes and 24 were up-regulated genes,12 were down-regulated genes.The names of the 12 paths are as follows: ABC transporters(Enriched 10 different genes),Alanine,aspartate and glutamate metabolism(Enriched 6 different genes),Glycolysis / Gluconeogenesis(Enriched 7 different genes),Nicotinate and nicotinamide metabolism(Enriched 4 different genes),2-Oxocarboxylic acid metabolism(Enriched 2 different genes),Sulfur metabolism(Enriched 1 different gene),Glycosaminoglycan biosynthesis-heparan sulfate / heparin(Enriched 2 different genes),Biosynthesis of amino acids(Enriched 4 different genes),Terpenoid backbone biosynthesis(Enriched 1 different gene)and Glyoxylate and dicarboxylate metabolism(Enriched 1 different gene),Arginine and proline metabolism(Enriched 2 different genes),Calcium signaling pathway(Enriched 9 different genes);(5)The dietary threonine level 125% of the recommended standard compared with 100% of the recommended standard,to list the important biological genes regulation trend related to antioxidant and immunity,up-regulated gene: GPT,GLUD2,G6 PC,PLCD1 and down regulated gene: PKM2,HK2 and TBXA2 R.The antioxidant gene CAT was up-regulated.PLCD1 is up-regulated which is involved in immune signal transduction and plays a role in cancer suppression.Carcinogenic or similar gene PKM2,HK2,TBXA2 R are down-regulated.The GPT2,GLUD2 and G6 PC,which are important to maintain homeostasis,are upregulated.Conclusions:(1)The levels of threonine 85% and 150% were higher than that of the standard recommended amount of NRC(1994)after feeding,the profiles of differential metabolites in experimental animals were similar,and there was no significant difference in cecum metabolites in poultry.(2)The level of threonine 125% of the recommended standard for NRC(1994)compared with the standard quantity,the metabolic profiles of experimental animals were significantly different,resulting in significant differences in cecum metabolites in poultry.(3)The level of threonine 125% of the recommended standard for NRC(1994)compared with the standard quantity,the anti-oxidation gene CAT was up-regulated,and it was involved in the immune signal transduction and up-regulation of the tumor-inhibiting gene PLCD1.The gene GPT2,GLUT2 and G6 PC were up-regulated in the gene GPT2,GLUT2 and G6 PC which were important for maintaining the steady state of the body.In particular,the horizontal threonine can improve the anti-oxidation performance and the immunity of the poultry,and enhance the ability of the poultry to resist the abnormal proliferation of the virus and the in vivo cells.