Effects Of Tannic Acid On Intestinal Barrier And Microbiome Communities Of Chick Caecum Infected By Eimeria Tenella

Purpose and meaning:In the past few decades,chemical drugs have long been used to fight coccidiosis and achieved effective result.However,with the continuous use of chemicals,coccidia is becoming less sensitive to chemicals,and residues of chemical drug in poultry products may pose a risk to the health of consumers.Therefore,it is urgent to find other drug methods to control coccidiosis.Tannic acid is a kind of polyphenolic compound with complex structure,which has good anti-diarrhea,anti-bacterial,anti-oxidation,anti-inflammation and anti-parasite effects.This experiment mainly explored the possible pathway and mechanisms of tannic acid's influence on intestinal barrier and intestinal microbes of young chickens infected by Eimeria tenella,in order to provide theoretical basis and research direction for the application of tannic acid in animal production.A 2×2 random block design was used to divide 144 1-day-old chicks into 4groups,36 in each group.The main effects include diet treatment(with 0 or0.4%tannic acid added)and challenge treatment(coccidial oocysts or the same volume of normal saline).During the experiment,the chicks of each group were fed a basic diet or an additional 0.4%dose of tannic acid,and inoculated with7×10~4-7.5×10~4coccidia oocysts or the same volume of saline on the 28th day of the experiment.We recorded and observed the relative weight gain,intestinal morphology,intestinal injury score,oocysts per gram(OPG)and fecal score of experimental animals,detected ZO-1,Claudin 1,Occludin,IL-6,IL-8,NF-k B gene expression level in chicks caecum tissue,identified chicks cecum intestinal flora using 16Sr RNA technology,measured short chain fatty acids(SCFA)in the chicks ceacum using GC-MS targeted metabolomics technique,and performed association analysis of 16Sr RNA and GC-MS targeted metabolomics technique.1?Inoculation of E.tenella reduces the relative weight gain of chicks;inhibits the expression of ZO-1,Claudin-1 and Occludin;promotes the expression of IL-6,IL-8 and NF-kb;reduces the probiotics(Faecalibacterium,Ruminococcaceae,Lactobacillus)relative abundance and short-chain fatty acid content;increased the relative abundance of conditional pathogenic bacteria(Escherichia-Shigella)and Clostridium sensu stricto 1 in the caecum.2?Add tannic acid to promote the expression of Occludin in the cecum of the chicks;increase the relative abundance of short-chain fatty acid-producing microorganisms(Barnesiella)and the content of acetic acid;there is a tendency to increase the content of propionic acid,butyric acid,isoxanoic acid and total short-chain fatty acids;Inhibited the decrease in Occludin expression and relative weight gain of chicks caused by E.tenella;relieved the increase of IL-6,NF-kb and the relative the abundance of Clostridium sensu stricto 1 in chicks caused by E.tenella Increased degree;reduced OPG,cecal injury score and fecal score of E.tenella infected chicks.3?Correlation analysis the results of intestinal microbes and SCFA of infected chicks showed that the content of SCFA was negatively correlated with the relative abundance of Clostridium sensu stricto 1(p=0.04,r=-0.66);The intestinal microbes and SCFA of uninfected chicks showed that the relative abundance of acetic acid producing microbes(Barnesiella)was positively correlated with the content of acetic acid and total short-chain fatty acids(p=0.04,r=0.90;p<0.01,R=1.00).Conclusion:1.When the chicks were not infected with Eimeria tenella,tannic acid treatment could protect the intestinal barrier by regulating the expression of Occludin in the caecum and indirectly alter the content of short-chain fatty acids in the caecum by regulating the intestinal Barnesiella,when the chick is not infected with Eimeria tenella.2.Tannic acid treatment relieved relative weight gain and decreased intestinal inflammation and intestinal barrier damage induced by E.tenella.In addition,the damage of intestinal epithelial cells could lead to the leak of intracellular proteins and the increase of mucus volume,which could provide a substrate for the growth of Clostridium sensu stricto 1.While the number of clostridium microbes was decreased after tannic acid treatment,which indicated that tannic acid may reduce the damage of the chicks intestinal epithelial cells by E.tenella.