Effects Of Grape Pomace On Growth Performance,the Morphological,Function And Microbiota Of The Gastrointestinal Tract In Tan Sheep

China as a large livestock country feed demand is huge,but feed resources are limited,so many feed ingredients rely on imports.Grape pomace,a by-product of grape processing,contains a large amount of crude fiber and other nutrients and has a certain feeding value.In this study,Tan sheep were fed a total mixed ration containing 0%(CON),1%(GP1),2%(GP2),4%(GP4)and 8%(GP8)grape pomace.The feeding effect was evaluated in four aspects:growth performance,gastrointestinal morphology,digestive enzyme activity and the composition and structure of bacteria and archaea,the mechanism of interaction between nutrition,microorganism and host was also preliminarily explored.The results showed that(1)there was no significant difference in ADG and FCR of each group(P>0.05),the ADFI of GP1,GP2 and GP4 decreased.GP4 has higher ADG,and ADF1 of GP8 was significantly higher(P<0.05).(2)Jejunal villus height and colonic mucosal layer thickness were the highest values in GP4,while jejunal muscle layer thickness,colonic muscle layer and mucosal layer thickness were lower in GP8(P>0.05).(3)In rumen fluid,the pepsin activity of GP8 was significantly higher than other groups,and the lipase activity of GP2 and GP4 was significantly lower than each group(P<0.05).In jejunal contents,GP4 had the highest activities of trypsin,chymotrypsin and lipase.In the cecum and colon contents,cellulase and lipase activities were higher in GP4 and GP8(P>0.05).(4)The structure of bacteria and archaea(adiversity and β-diversity)in the gastrointestinal tract did not change significantly(P>0.05)after feeding the grape pomace,and the abundance of some bacterial in GP4 and GP8 was significantly altered.There was a slightly decrease in the abundance of Fibrobacteraceae,Candidatus_Soleaferrea and Oscillibacter.in the rumen,a significant increase in the abundance of Clostridium_disporicum and Prevotella_brevis in GP8,and a slightly decrease in Methanobacterium(P>0.05).The abundance of the Phylum Bacteroidetes.Rikenellaceae,Muribaculaceae and unclassified Prevotellaceae was higher in GP4 in the jejunum than in all groups,while the abundance of Prevotellaceae was slightly lower(P>0.05).The highest abundance was found in the cecum for GP4 of Romboutsia,Paeniclostridium,unclassified Veillonellaceae,Aeriscardovia and Kandleria,and the lowest abundance was found in the Bacteroides,unclassified Ruminococcaceae and Akkermansia.The abundance of Ruminococcaceae was lower in the colon with GP8 and the highest abundance of Bacillus,Romboutsia and unclassified Enterobacteriaceae.The core functions of gastrointestinal bacteria did not change significantly,with a decreasing trend in the core metabolic pathways in the rumen and colon of GP8 and in the jejunum and cecum of GP4.The abundance of the biosynthetic pathways of L-lysine and O-polysaccharide in the rumen of GP8 decreased,and those of L-aspartate and L-asparagine,phosphopantothenic acid and histidine,purines and pyrimidines were significantly higher(P<0.05).The biosynthesis of 5’-inosinic acid,L-threonine,O-polysaccharide,and Lmethionine was significantly elevated in the jejunum(P<0.05).The abundance of O-polysaccharide,Lmethionine,vitamin B6 biosynthesis and D-galacturonic acid degradation pathway was decreased in the cecum,and the abundance of arginine and polyamine biosynthesis pathway was significantly increased(P<0.05).L-lysine,L-threonine and L-methionine biosynthesis were significantly enriched in the colon,and the fermentation of glucose into lactate pathway was significantly reduced(P<0.05).Some groups of bacteria play a key role in the growth of Tan sheep:the probiotic bacteria Lactobacillus and Butyricicoccus in the rumen and Lachnoclostridium in the colon were significantly and positively correlated with ADG;the pathogenic bacteria Paeniclostridium and Turicibacter in the rumen Blautia and Shuttleworthia in the colon were significantly and negatively correlated with ADG;the abundance of Methanosphaera in the rumen,Oribacterium,Lachnobacterium and Saccharofermentans in the jejunum,Alloprevotella in the cecum were significantly and positively correlated with ADFI;the abundance of Unidentified_Prevotellaceae in the jejunum,Candidatus Methanomethylophilus in the cecum,and Fibrobacter in the colon were significantly and negatively correlated with ADFI;the abundance of Paeniclostridium in the rumen was significantly and negatively correlated with ADFI.The abundance of pathogenic bacteria Paeniclostridium,Turicibacter,Saccharofermentans in the jejunum and Blautia in the colon were all significantly and positively correlated with FCR,while the abundance of Unidentified_Prevotellaceae in the jejunum,Tyzzerella and Epulopiscium in the colon were significantly and negatively correlated with FCR.In conchusion,a 4%-8%grape pomace could alter the abundance and function of specific microbiota in the gastrointestinal tract of Tan sheep,improve histomorphological indicators and promote the secretion of digestive enzymes to promote animal growth performance and development.