Effects Of Microcapsule Tannic Acid On Nutrient Digestibility,Growth Performance And Intestinal Health Of Piglets

Tannic acid is one of the functional additives widely used in the diet of weaned piglets after"Prohibition of antibiotics"and"limited use of zinc oxide",which plays an important role in intestinal health of piglets.Tannic acid has a negative effect on dietary palatability and amino acid digestibility,so tannic acid is gradually processed by microencapsulation to overcome its anti-nutritional properties.However,the regulatory effects and mechanisms of tannic acid treated in microcapsules on growth performance and intestinal health of weaned piglets remain unclear,and the effects of tannic acid on standardized ileal digestibility of amino acids of weaned piglets remain to be confirmed.Two experiments were conducted.Firstly,the effects of microencapsulated tannic acid and unmicroencapsulated tannic acid on nutrient digestibility,amino acid ileal digestibility and digestive enzyme activities of piglets fitted with T-cannula in the distal ileum were compared.In experiment 2,microcapsules tannic acid was supplemented to the used diets containing high or low levels of plant dietary protein to investigate the effects of tannic acid on growth performance and intestinal health of piglets.These two experiments provide theoretical basis and reference data for the rational application of tannic acid in weaned piglets diet.Experiment 1.Effects of tannic acid in basal diet on nutrient digestibility and digestive enzyme activities in pigletsThe objective of this study was to determine the effects of high/low dose tannic acid on conventional nutrient digestibility,apparent(AID)and standardized(SID)ileal digestibility of amino acid and digestive enzyme activities in piglets.There are two trials in this experiment.For high dose tannic acid trial,nine barrows with initial body weight of 34.79±3.34kg were used to install T-cannula in the distal ileum.At the beginning of the the experiment,all pigs were fed a nitrogen-free diet for 7 d to collect ileum digesta.Nine pigs were randomly assigned to one of three experimental diets including 1)bases diet,2)based diet supplemented with 2%microcapsule tannic acid,3)based diet supplemented with 1.143%tannic acid power in a two-period crossover trial design with three pigs per diet per period to give 6 replicates per treatment.Both tannic acid supplemented diets provided 0.8%tannic acid.Each experimental period lasted for 11d,starting with a 7 d adaptation period.Feces were collected on day 8 and 9 and ileal digesta was collected on days 10 and 11.For low dose tannic acid trial,eight barrows with initial body weight of 15.49±1.92 kg were used to install T-cannula in the distal ileum.Then,they were allocated to 4dietary treatments including 1)bases diet,2)based diet supplemented with 0.175%microcapsule tannic acid,3)based diet supplemented with 0.1%tannic acid power,and4)nitrogen-free diet according to an incomplete replicated 4×3 Latin square design with 3 periods to give 6 replicates per treatment.The diet 2 and 3 contained similar level of tannic acid.Each experimental period lasted for 11d,starting with a 7 d adaptation period.Feces were collected on day 8 and 9 and ileal digesta was collected on day 10 and 11.Results showed:1.The AID of CP were decreased by high-dose tannic acid power supplementation(P<0.05);The ATTD of DM,OM and CP were decreased by the supplementation of high-dose microcapsules tannic acid and tannic acid powder(P<0.05).The AID and SID of Arg,His,Leu,Asp,Glu,and Tyr were decreased by high-dose microcapsules tannic acid supplementation(P<0.05),but it did not affect the digestibility of total AA.The AID and SID of Arg,His,Ile,Leu,Lys,Met,Phe,Thr,Val,Ala,Asp,Cys,Glu,Ser,Tyr,and total AA were decreased by high-dose tannic acid powder supplementation(P<0.05).The supplementation of high-dose microcapsules tannic acid and tannic acid powder decreased the activities of trypsin andα-amylase in ileum digesta of piglets.2.The AID of DM,OM and GE and ileum DE were decreased by low-dose tannic acid powder supplementation(P<0.05).The supplementation of low-dose tannic acid powder in the basal diet decreased the activities ofα-amylase in ileum digesta of piglets.In summary,compared with the high-dose microcapsules tannic acid supplementation,the supplementation of high-dose tannic acid powder had more serious negative effects on nutrient digestibility,especially AID and SID of AA.In addition,the supplementation of low-dose microcapsules tannic acid had no negative effect on nutrient digestibility of piglet,but the AID of DM,OM and GE and ileum DE were decreased by low-dose tannic acid powder supplementation.Experiment 2.Effects of microcapsule Tannic acid supplementation in different levels plant protein diets on growth performance and intestinal health of weaned pigletsIn experiment 1,low-dose microcapsules of tannic acid had no negative effect on nutrient digestibility of piglets.Therefore,low-dose microcapsules of tannic acid were supplementation in experiment 2 to investigate the effects of microcapsules of tannic acid on growth performance and intestinal health of weaned piglets.One hundred and twenty eight weaned piglets with BW of 7.62±0.44 kg were used in a 2×2 factorial experiment for 28-d.The factors were plant protein levels(low levels plant protein vs.high levels plant protein)and microcapsules tannic acid levels(0 vs.1000 mg/kg).Piglets were randomly allotted to 4 treatments with 8 replicate pens and 4 pigs per pen according to their initial BW.Blood was collected and slaughtered for sampling at the end of the experiment.Results showed that:1.Compared to a low level plant protein diet,the diarrhea index and diarrhea rate were increased by high level plant protein diet(P<0.05);the jejunum villus height of piglets were decreased by high level plant protein diet(P<0.05);the Treg cell proportion of colonic tissues were increased by high level plant protein diet(P<0.05);the butyric acid,valerate acid were decreased by high level plant protein diet(P<0.05);at phylum level,the relative abundance of Campylobacterota were increased by high level plant protein diet(P<0.05);at genus level,the relative abundance of Clostridium＿sensu＿stricto＿1,Ligilactobacillus,Agathobacter and Sutterella were decreased by high level plant protein diet(P<0.05).2.Dietary microcapsules tannic acid supplementation did not affect the growth performance of piglets(P>0.05),but the diarrhea index and diarrhea rate of piglets were decreased by microcapsules tannic acid(P<0.05);the CD4~+immune cell levels of serum in piglets were increased by microcapsules tannic acid(P<0.05),and the IL-6concentrations of serum samples were decreased by microcapsules tannic acid(P<0.05);the ileum villus height and s Ig A levels in ileum mucosa concentration of piglets was increased by microcapsules tannic acid(P<0.05),and the serum D-Lactate concentration and Treg cell proportion of colonic tissues of piglets were decreased by microcapsules tannic acid(P<0.05);the acetic acid,propionic acid,butyric acid,isobutyric acid and contents in colonic digesta were increased by microcapsules tannic acid(P<0.05);at phylum level,the relative abundance of Bacteroidota were increased by microcapsules tannic acid(P<0.05).at genus level,the relative abundance of Rikenellaceae＿RC9＿gut＿group and Agathobacter were increased by microcapsules tannic acid,and relative abundance of Escherichia-Shigella and Sutterella were decreased by microcapsules tannic acid(P<0.05).The findings in experiment 2 demonstrated that dietary supplementation of microcapsules tannic acid has no negative effect on growth performance of weaned piglets,but can improve intestinal health and microbial structure of weaned piglets and relieve diarrhea after weaning.In conclusion,the present study demonstrated that:1)Microencapsulation of tannic acid reduced its negative effect on the digestibility of dietary nutrients,especially the SID of amino acid.2)Microencapsulated tannic acid can regulate the balance of microflora,promote intestinal health,and alleviate diarrhea of piglets caused by high dietary inclusion level of plant protein diets after weaning.