Effects Of Coated Tannic Acid On Growth Performance, Diarrhea And Intestinal Function Of Weaned Piglets

Hydrolyzed tannic acid is a kind of polyphenols widely existing in plants.It has biological functions such as antibacterial and antioxidant,and has been reported to be a potential functional additive in animal husbandry,such as anti-diarrhea and growth promotion.However,its palatability is poor,and it is easy to be oxidized and destroyed by gastric acid,which limits its application in feed.This experiment analyzed the different sources of tannic acid in vitro antioxidant capacity,on the basis of to "Duroc×Landrace×Yorkshire" ternary hybrid weaned piglets as test object,studies the coated tannins on weaning piglet growth performance,apparent digestibility of nutrients and digestive enzyme activity and the influence of intestinal function,and uses the 16s rDNA sequencing technology to explore their effects on intestinal structure and function,is intended to provide a scientific basis for the application of coated tannins in feed.Three hundred 28-day-old "Duroc×Landrace×Yorkshire" crossbred weaned piglets were randomly divided into 5 groups with 3 replicates per group and 20 piglets per replicate.The control group was fed corn soybean meal based diet(containing ZnSO4).In coated tannic acid group,0.1%,0.15%and 0.2%coated tannic acid were added to the basal diet,respectively.The zinc oxide group substituted zinc oxide for ZnSO4 in the basal diet,and the zinc content was 1600mg/kg.20 days of the trial period,after the feeding experiment,selecting the optimal growth performance of coated tannins group,control group and zinc oxide 0.15%,were randomly selected from each treatment group 6(each repeat two head),a total of 18 experimental pig slaughtering experiment,serum and intestinal mucosa,intestinal contents samples related index measurement,the main results were as follows:1.In vitro antioxidant capacity of tannic acidThere was no significant difference in the antioxidant capacity of tannic acid from different sources(P>0.05)and were stronger than vitamin C(P<0.05).2.Growth performance and diarrhea rateCompared with the control group,ADG in 0.15%coated tannic acid group increased by 22.2%(P<0.05),F/G decreased by 10.3%(P<0.05),the diarrhea rate decreased by 51.3%(P<0.05),There was no significant difference between the coated tannic acid group and the zinc oxide group3.Nutrient apparent digestibility and digestive enzyme activityCompared with the control group,crude protein digestibility in coated tannic acid group was significantly increased(P<0.05),and had no difference with zinc oxide group(P>0.05);There was no difference in the digestibility of other substances between the control group and the control group(P>0.05);Pancreatic and duodenal trypsin activity increased(P<0.05),slightly higher than that of zinc oxide group;The activity of maltase and sucrase in jejunal mucosa increased(P<0.05),had no difference with zinc oxide group(P>0.05).4.Intestinal morphology and functionCompared with the control group,the villus height of duodenum,jejunum and ileum and the velvety to secrete ratio in the coated tannic acid group were significantly increased(P<0.05)and had no difference compared with ZnO group(P>0.05);Under electron microscopy,the microvilli in the coated tannic acid group and the zinc oxide group were more complete than those in the control group.The microvilli in the coated tannic acid group were more neat and compact,and the mitochondrial structure was complete.The morphology of microvilli in the jejunum in the coated tannic acid group was better than that in the zinc oxide group.Serum diamine oxidase and endotoxin in the coated tannic acid group were lower than those in the control group(P<0.05),had no difference with zinc oxide group(P>0.05);The relative expression levels of ZO-1,Claudin-1 and Occludin in the coated tannin group were higher than those in the control group(P<0.05),the relative expression levels of ZO-1 and Claudin-1 were significantly higher than those in zinc oxide group(P<0.05).5.Gut Microfloraα diversity:Simpson and Shannon diversity index of the coated tannic acid group was significantly higher than that of the zinc oxide group(P<0.05)and had no difference with the control group(P>0.05).Microflora structure:Firmicutes and Bacteroidetes in the three groups were the absolute dominant phyla at phylum level.At the family level,the highest relative abundance of Ruminococcaceae was found in the coated tannic acid group and zinc oxide group,followed by Trichoricaceae,while the relative abundance of Ruminococcaceae in the control group was lower than that of Trichoricaceae.LEFSE difference analysis showed that at the genus level,compared with the control group,the number of Coprobacillus,Enterobacterium faecalis,Aminococcus,Methanosmith,Turicibacter,etc.in the coated tannic acid group increased significantly(P<0.05);Compared with the zinc oxide group,the number of Coprobacillus,Prevotella,Roxella,and Megalococcus in the coated tannic acid group increased(P<0.05),the number of genera,such as Entomobacteria,Faecalicoccus,and Cholophilus decreased(P<0.05).6.Antioxidant capacity and biochemical indexes of serum and liverCompared with the control group,the serum and liver T-AOC,T-SOD and GSH-Px activities of coated tannic acid and zinc oxide groups were significantly increased(P<0.05),MDA content was significantly decreased(P<0.05);There was no difference between the coated tannic acid group and the zinc oxide group(P>0.05).Alkaline phosphatase activity increased(P<0.05),urea nitrogen content decreased(P<0.05)and had no difference compared with ZnO group(P>0.05).The glutamic-pyruvic transaminase activity in zinc oxide group decreased compared with that in coated tannic acid group(P<0.05).These results indicate that coated tannic acid can significantly increase the daily gain,reduce the ratio of feed to gain,reduce the diarrhea rate and improve the antioxidant capacity of piglets.Improve the morphology and cellular connection of villi and microvilli,and enhance the intestinal barrier function;Increased crude protein digestibility and the activities of trypsin and jejunal disaccharase;Change the structure of intestinal flora,increase the abundance of butyric acid producing bacteria and other beneficial bacteria,and improve the abundance of "butyrate metabolism","propionate metabolism","tight linkage" and other functional related genes;In this experiment,the optimal addition amount of coated tannic acid was 0.15%.The results indicate that coated tannic acid has the same effect as high dose zinc oxide in promoting growth and reducing diarrhea rate,and is superior to zinc oxide in improving intestinal barrier function and intestinal microflora structure and function.