Effects Of Dietary Quercetin Supplementation On Diarrhea And Gut Microbiota In Early Weaned Piglets

Early weaning of piglets is a key strategy to improve the efficiency of modern pig production systems,but early weaning stress can lead to reduced growth performance and even death of piglets.Gut oxidative stress is one of the main factors leading to intestinal damage,gut microbial dysbiosis,diarrhea,anorexia and growth arrest in early weaned piglets.As a flavonoid polyphenol molecule,quercetin is commonly found in vegetables,fruits and Chinese herbal medicines,and has strong antioxidant capacity.This study determined the effect of quercetin in improving diarrhea,intestinal damage and gut oxidative stress by supplementing 0.1% quercetin in early weaned piglet diets.Meanwhile,we transplanted the fecal microbiota of quercetin treated piglets into the intestine of FMT recipient piglets to determine the role of gut microbiota in the quercetin’s function.We selected 63 21-day-old weaned piglets(Duroc × Landrace × Yorkshire)and randomly divided them into three treatment groups with 21 piglets each treatment(Three pens per treatment,7 piglets per pen).The three treatment groups: control group(Ctrl),quercetin group(QT)and fecal microbiota transplantation group(FQT).The Ctrl and FQT groups were fed a basal diet after weaning,and the QT group was fed a basal diet supplemented with 0.1% quercetin(the dose of quercetin was added based on Ader’s results).The piglets in the FQT group were fed 2 m L of fecal bacterial suspension collected from the QT group,and the Ctrl group and the QT group were fed 2 m L of normal saline from the 2nd to the 10 th day after weaning.On day 14 after weaning,20piglets(6 in the Ctrl group;7 in the QT group;7 in the FQT group)were randomly selected for slaughter sampling.The main results are as follows:(1)The quercetin and FMT can alleviate the diarrhea of ??weaned piglets and improve their growth performance.Compared with the Ctrl group,ADFI(P < 0.05)and ADG(P < 0.01)increased in QT and FQT groups after weaning on days 7-14,and on days7(P < 0.01)and 14(P < 0.05)decreased stool scores.(2)The quercetin and FMT improved the intestinal morphology and intestinal barrier function of weaned piglets and alleviate the gut oxidative stress.Compared with the Ctrl group,the jejunum morphology was significantly improved in the QT group and the FQT group;the villus height(P < 0.05)and the villus height/crypt depth ratio(P< 0.001)of the jejunal tissue were increased in the QT group and the FQT group;the expression of tight junction protein Occludin was increased in jejunum tissue(P <0.05)of the QT group and the FQT group.The analysis of the antioxidant capacity of jejunum tissue showed that compared with the Ctrl group,the QT group and the FQT group increased the antioxidant indexes such as T-AOC(P < 0.05),CAT(P <0.01)and GSH/GSSG(P < 0.01).And the level of oxidative metabolite MDA in jejunum tissue decreased(P < 0.01).(3)Dietary supplementation of quercetin and FMT improved the structure and diversity of gut microbiota in weaned piglets.16 S r DNA amplicon sequencing analysis showed that the Beta diversity between groups(PC1 and PC2 explained 48.85% of the variance)indicated that the QT group(P < 0.01)and the FQT group(P < 0.05)formed a significantly different group from the Ctrl group,respectively.Compared with the Ctrl group,the Alpha diversity indices Observed species(P < 0.01),Chao1(P < 0.05),ACE(P < 0.05)and PD＿whole＿tree(P < 0.01)were significantly increased in the QT group and ACE(P < 0.01)in the FQT group were significantly reduced.(4)Dietary supplementation of quercetin and FMT altered the gut microbial structure and metabolic phenotype of weaned piglets.Relative abundance of Fibrobacteres(P <0.05),Akkermansia muciniphila(P < 0.01),Clostridium butyricum(P < 0.01),Clostridium celatum(P < 0.01),and Prevotella copri(P < 0.05)in the QT group compared with the Ctrl group The relative abundance of Proteobacteria(P < 0.01),Lactobacillus coleohominis(P < 0.01)and Ruminococcus bromii(P < 0.05)decreased;the relative abundance of Akkermansia muciniphila in the FQT group increased(P < 0.05),but the relative abundance of Proteobacteria decreased(P <0.05).In addition,the Bug Base prediction results showed that the relative abundances of gut microbes in the QT and FQT groups were significantly different from those in the Ctrl group(Ctrl vs.QT,P < 0.01;Ctrl vs.FQT,P < 0.05).(5)Dietary supplementation of quercetin and FMT altered the function and metabolites of gut microbes in weaned piglets.The PICRUSt2 function prediction results showed that compared with the Ctrl group,the QT and FQT groups had improved functions of carbohydrate metabolism,membrane transport,translation,and nucleotide metabolism,Global and overview maps,cofactor and vitamin metabolism,and energy Metabolism and other functions decline.Compared with the Ctrl group,the concentrations of short-chain fatty acids(SCFAs)(propionic acid,P < 0.01;butyric acid,P < 0.05)were increased in the colonic and jejunal contents of the QT and FQT groups.(6)The differential gut microbes and metabolites induced by dietary supplementation of quercetin and FMT were significantly correlated with the antioxidant capacity and gut integrity indices of piglets.Using Spearman’s rank correlation analysis and significance test,identified differential bacteria and elevated SCFAs concentrations were significantly positively associated with indicators of antioxidant capacity and gut integrity.Summary: Quercetin supplementation in the diet alleviated oxidative stress,diarrhea and intestinal damage in early weaned piglets,improved gut microbial diversity and function in early weaned piglets.FMT further demonstrated that gut microbes were involved in the alleviation effect of dietary quercetin on early weaning stress in piglets.