Effects Of Taratanic Acid On Growth Performance,Serum Biochemistry And Intestinal Barrier Function Of Weaned Piglets

Tannins are natural polyphenols that can play a variety of biological roles in animals such as astringent,antibacterial,anti-inflammatory and antioxidant.Tara is native to South America and is also grown in small quantities in Yunnan,Guizhou and Sichuan in China.The content of tannins in tara fruit reaches 55%-61%,which can replace some of the traditional Chinese medicines such as pentospermum and fill the demanding gap of plant-derived tannins in China.In order to investigate the effect of tara hydrolyzed tannins in weaned piglets,200 piglets weaned at 28 days of age and with similar weights were selected for feeding trial based on the evaluation of the in-vitro antibacterial effect of tara tannins.The control group was fed the basal diet,and the four experimental groups were fed 250,500,750,1000 g/t tara hydrolyzed tannic acid in the basal diet for 28 days.During the experiment,piglets’ weight gain was measured,feed intake and diarrhea situation were recorded,and slaughter was performed at the end of the experiment,and blood,cecum surimi and tissue samples were collected to determine indexes associated with antioxidant,immunity,intestinal structure,intestinal cupped cell count,intestinal tight junction protein expression and intestinal microorganism.The results of the experiments were as follow:(1)Tara hydrolyzed tannic acid showed the most significant antibacterial effect against Bacillus subtilis within the tested concentrations(0.78-25 mg/m L)and the weaker antibacterial effect on E.coli.There was no significant inhibition effect on Clostridium perfringens,yeast or Lactobacillus.(2)Different concentrations of tara hydrolyzed tannic acid had no significant effects on the performance indexes of weaned piglets such as daily weight gain,feed intake,meat ratio,diarrhea rate,diarrhea index and mortality rate(P>0.05).(3)Serum CAT content was significantly higher in the experimental groups than that of the control group(P<0.01);serum SOD content was significantly higher in the experimental groups than that of the control group(P<0.01),except that experimental Group 4(1000 g/t)was not significantly different from that of the control group(P>0.05).Experimental Group 3(750 g/t) had the highest CAT content among all groups.Serum GSH-Px content was significantly lower in experimental Group 1(250 g/t)and experimental Group 2(750 g/t),but significantly higher in experimental Group 4(1000 g/t)than the control group(P<0.01),but the difference between experimental Group 3 and the control group was not significant.Serum MDA content was significantly lower in the experimental groups than the control group,except experimental Group 4(1000 g/t)(P<0.01).Serum T-AOC capacity was lower in experimental Group 1(250g/t)than the control group,but the remaining experimental groups were all higher than the control group(P<0.05),among which the T-AOC capacity in experimental Group 2(500 g/t)was the highest.(4)Compared with the control group,the serum Ig A and complement C4 contents in the experimental groups were significant increased(P<0.01),that experimental Group 3 had the highest Ig A content(89.00%)and experimental Group 2 had the highest complement C4 content(78.15%).Serum interferon-γ,tumor necrosis factor TNF-α and interleukin IL-1β contents in the experimental groups were also significantly increased compared to the control group(P<0.01).(5)The addition of tara hydrolyzed tannic acid in the diet did not affect the height of duodenal villi in weaned piglets(P>0.05),but when 500 g/t tannic acid was added,it significantly reduced the depth of duodenal crypts,which in turn significantly increased the ratio of villi to crypts(P<0.05).The addition of tara hydrolyzed tannic acid in the diet significantly increased the height of villi in the jejunum of weaned piglets(P<0.01),and in the range of 0-750g/t,the jejunal villus height increased as the addition of tannins increased.Tara hydrolyzed tannic acid also significantly decreased the jejunal crypt depth(P<0.05),that experimental Group 2(500 g/t)had the greatest decrease(27.28%).The jejunal crypt ratio was significantly higher in the experimental groups than the control group(P<0.05),with the trend of increasing first then decreasing,that experimental Group 2(500 g/t)had the greatest increase.The addition of tannic acid to the diet had no significant effect on the morphological development of ileum(P>0.05).The addition of tara hydrolyzed tannic acid in piglets’ diets had no significant effect on the number of cupped cells in any intestinal segment of piglets(P>0.05).(6)The addition of different concentrations of tara hydrolyzed tannic acid in the diet had no significant effects on the relative expressions of tight junction proteins including Occludin,Claudin-1 and ZO-1 in the jejunum,and Occludin and Claudin-1 in the ileum(P>0.05),but the relative expression of ZO-1 in the ileum of experimental Group 2(500 g/t)was significantly higher than those of the other groups(P<0.05).(7)The addition of tara hydrolyzed tannic acid to the diet had no significant effect on the alpha diversity of cecum flora in weaned piglets(P>0.05).In terms of flora structure,the dominant bacteria in all groups at the phylum level were the Firmicutes and the Bacteroides,and the relative abundance of Proteobacteria was significantly higher in the experimental Group2(500 g/t)than the other groups(P<0.05).The bacteria with the highest abundance at family level in the experimental groups and control group were Ruminococcaceae and Lactobacillaceae,respectively.At genus level,the relative abundance of Lactobacillus was lower in all experimental groups than the control group(P<0.05),and the relative abundance of Rothia was higher in the experimental Group 2(500 g/t)than the other groups(P<0.05).Linear discriminant effect size(LEf Se)difference analysis showed that experimental Group 1(250 g/t)had 2 marker bacteria,which were Weisseria spp.and Akebiaceae.Experimental Group 2(500g/t)had 2 marker bacteria,which were Amoebacteria and Aureobacteria.The experimental Group 4(1000 g/t)had 6 marker bacteria,which were Streptococcaceae,Streptococcus,Thermophilus,Enterococcaceae,Enterococcus and Bacillariophyceae.The gene sequence abundances in the samples were used to predict bacterial functions,and the abundance data of metabolic pathways were analyzed to identify the different KEGG metabolic pathway among groups.The abundance of genes related to toxoplasmosis and water reabsorption function was significantly lower(P<0.01)in the experimental Group 1(250 g/t)compared to the control group.The experimental Group 2(500 g/t)showed significantly higher levels of functions related to bacterial chemotaxis and unsaturated fatty acid production(P<0.05),and highly significantly higher levels of β-lactam resistance,insulin signaling pathway and vitamin B6metabolism(P<0.01)compared to the control group.Experimental Group 3(750 g/t)significantly increased the abundance of genes related to cytokinesis(P<0.05)and highly significantly increased the abundance of genes related to African trypanosomes and biosynthesis of penicillin and cephalosporins(P<0.01)compared to the control group.The abundance of genes related to water reabsorption function was highly significantly reduced in the experimental Group 4(1000 g/t)(P<0.01).The above results indicated that the addition of tara hydrolyzed tannins to piglet diets could improve the antioxidant capacity and immunity of weaned piglets,increase the number of intestinal tight junction proteins,improve the intestinal structure,maintain the function of intestinal mucosal barrier,change the structure of intestinal flora and increase the relative abundance of some beneficial bacteria.Considered together,the proper additive amount of tara hydrolyzed tannic acid in piglet diets was in the range of 500～750 g/t.