The Variety Of Gut Microbiota From Different Segments Of The Digestive Tract And Its Correlation With The Digestive Function In Weaned Altay Lambs

Gut microbiota is closely associated with host growth,metabolism,immunity and disease.However,Altay sheep,a famous local sheep meat breed raised mainly in Xinjiang on the pasture land,the compositional and structural difference in gut microbiota between different segment of digestive tract and their functional relationship with host growth,digestion and absorption in weaned lambs have not been well elucidated.In this study the composition and structure of gut microbiota in weaned Altay lambs were investigated,the correlations of gut microbiota with host grow(body weight),digestion and absorption were analyzed to get insight into their interaction between gut microbiota and lamb growth and development in weaned lambs.The fallowing experiments were conducted :Experiment 1 : Twelve 90-day-old Altay weaned lambs were selected as the research objects.After measuring body weight,lambs were sacrificed.Contents in oral,esophageal,rumen,reticulum,omasum,abomasum,duodenum,jejunum,ileum,cecum,colon and rectum were sampled.16 S r RNA sequencing technique was applied to study the composition structure and potential function of gut microbiota.Experiment 2 : The weaned lambs(half male and half female)in Experiment 1 were divided into high body weight group(HBW)and low body weight group(LBW),6 in each group,by statistically significant difference in body weight.Before slaughter,the body temperature,pulse,respiration was recorded,feces and blood collected.After slaughter,the organ coefficient,p H in different segments of intestinal tract were tested,the intestinal tissue and blood samples was collected,blood physio-biochemical indices were tested,the feces samples were collected for analyzing the composition and structure of gut microbiota by 16 S r RNA sequencing.Experiment 3 : ELISA was used to determine contents of amylase,maltase,lipase and protease in the small intestine,the Histometry of small intestine(duodenum,jejunum,ileum)was conducted by paraffin section technique.Spearman algorithm was used to analyze the correlation between gut microbiota and digestive enzymes and intestinal villus in weaned lambs with high and low body weight.Results showed :(1)The β-diversity of the microbiota in different segments of digestive tract was extremely independently distributed by adonis comparison(P < 0.01),characterized by 5 bacterial communities,namely,the community of oral and esophageal,the community of stomach(rumen,reticulum,omasum,abomasum)and duodenum,the community of jejunum,the community of the ileum and cecum,and the community of colon and rectum.The richness and diversity of gut microbiota were the highest in stomach,and the lowest in oral cavity,esophagus and jejunum.The main microbiota at phylum level in the whole gut of lambs were Firmicutes,Proteobacteria and Bacteroidetes.The main microbiota at genus level were Aquabacterium,Solibacillus and Prevotella.Proteobacteria and Streptococcus were biomarkers in oral and esophagus.Bacteroidetes and Butyrivibrio in stomach and duodenum.Actinobacteria and Aquabacterium in jejunum.Chlamydia and Arthrobacter in ileum and cecum.Verrucomicrobia,Akkermansia and Clostridium in colon and rectum.The predicted functions of the gut microbiota mainly included Amino Acid Biosynthesis,Cofactor,Prosthetic Group,Electron Carrier,and Vitamin Biosynthesis,Fatty Acid and Lipid Biosynthesis,Nucleoside and Nucleotide Biosynthesis,Carbohydrate Degradation,Carboxylate Degradation,Inorganic Nutrient Metabolism and Fermentation.At KEGG Level 2 level,35 metabolic pathways were detected in microbiota,There were 18 pathways with significantly differences between five independent bacterial communities.(2)There were no significantly difference in TPR index,organ coefficient and p H value of gut between HBW and LBW group(P > 0.05).Blood PLT and AST in HBW group were extremely higher than that in LBW group(P < 0.01).Though there was no significantly difference in the α diversity andβ diversity of gut microbiota(P > 0.05),the relative abundance of Firmicutes in HBW group was extremely higher than that in LBW group(P < 0.01),the relative abundance of Verrucomicrobia and Akkermansia were extremely lower than that in LBW group(P < 0.01).(3)The content of digestive enzymes(amylase,maltase,lipase and protease)in HBW group was extremely higher than that in LBW group(P < 0.01),and the duodenum mucosa thickness was extremely higher than that in LBW group(P < 0.01).There was significant difference in β-diversity of small intestine microbiota between HBW and LBW group(P > 0.05).In HBW weaned lambs,the relative abundance of Aquabacterium was negatively correlated with contents of lipase content(r <0,P < 0.05),maltase and amylaseand positively correlated with villus height,crypt depth in small intestine(r > 0,P < 0.05).In LBW weaned lambs the relative abundance of Firmicutes was negatively correlated with the content of amylase(r < 0,P < 0.05),and positive correlated with the villus height in the small intestine(r > 0,P < 0.05).The relative abundance of Proteobacteria was positively correlated with the content of amylase(r > 0,P < 0.05),and negatively correlated with villus height in the small intestine(r < 0,P < 0.05).It is concluded :The composition and structure of microbiota in the whole digestive tract of weaned lambs are significantly different,forming 5 independently distributed bacterial community.The symbolic species and prediction functions of each community are different.The differences in the number of platelets and aspartate aminotransferase content in the blood,the relative abundance of Firmicutes,Verrucomicrobia and Akkermansia in the small intestine could be related to the bodyweight difference in weaned lambs.The correlation between Firmicutes and the small intestinal villi height,the correlation between Proteobacteria and amylase and villus height in small intestine could be associated with the lower body weight in weaned lambs.The correlation between Aquabacterium and maltase,amylase,villus height,crypt depth and lipase could be associated with the higher body weight in weaned lambs.Our study laid a scientific foundation for the research and development of technology to promote the growth and development of weaned lambs via early gut microbiota intervention.