Effect Of Tannins On The Morphological Function And Microbiota Of The Gastrointestinal Tract Of Sheep

Objective: The aim of this study was to investigate the changes in daily feed intake and daily weight gain,antioxidant capacity of jejunum,morphological structure and digestive enzyme activity of rumen,duodenum,ileum and cecum,and microbial diversity and abundance of rumen and cecum in sheep fed with different concentrations of tannins.Method:Experiment 1: Effect of tannin addition to rations on growth performance and jejunal antioxidant properties of sheepThirty six sheep male lambs with similar body weight(30.65 ± 3.29)kg were randomly divided into four groups of 9 replicates in each group.The control group was fed the basal diet and the experimental group was fed 0.15%,0.3% and 0.45% of tannin in the basal diet,respectively.The test was conducted for67 days,with a pre-feeding period of 7 days and a positive feeding period of 60 days.The initial weight,final weight and ration consumption were recorded,and the average daily weight gain,average daily feed intake and feed conversion ratio were calculated.On the last day of feeding,the animals were fasted for 24 h and water fasted for 12 h.Three animals in each group were randomly selected for slaughter test after bloodletting in the early morning of the second day,and the jejunal intestinal mucosa was collected for the determination of intestinal antioxidant properties.Experiment 2: Effect of tannin addition to rations on morphological structure and digestive enzyme activity in the gastrointestinal tract of sheepAfter slaughter,the abdominal cavity was opened to remove the visceral organs,and the parts of the gastrointestinal tract were ligated in sections,and the contents of the rumen,duodenum,ileum and cecum were taken in lyophilized tubes and immediately put into liquid nitrogen for the determination of gastrointestinal digestive enzyme activity.The rumen intestinal tissues and intestinal segments of duodenum,ileum and cecum were soaked and fixed in 4% paraformaldehyde,and the intestinal tissue morphology was observed by making tissue sections.Experiment 3: Effect of tannin addition to rations on microbial diversity in the rumen and cecum of sheepRumen fluid was collected after slaughter,and cecal contents were stored in liquid nitrogen immediately after freezing tubes for subsequent sequencing.Results:1.After tannins were added to the diet,the final body weight of the 0.45% tannin group was significantly lower than that of the 0.3% tannin group(P<0.05);the average daily weight gain of the 0.3%tannin group was significantly higher than that of the control group and the 0.45% tannin group(P<0.05),and the daily feed intake of the 0.45% tannin group was significantly lower than that of the control group,the 0.15% tannin group and the 0.3% tannin group(P<0.05);the total antioxidant capacity of the 0.15%tannin group was significantly higher than that of the control group(P<0.05).The total antioxidant capacity of the 0.15% tannin group was significantly higher than that of the control group(P<0.05);the superoxide dismutase content of the 0.15% tannin group was significantly higher than that of the control group and the0.45% tannin group(P<0.05);the glutathione peroxidase content of the 0.15% tannin group was higher than that of the 0.45% tannin group(P<0.05);the malondialdehyde content of the control group was significantly higher than that of the 0.3% tannin group and 0.45% tannin group(P<0.05).2.After the addition of tannins to the diet,the height of the rumen papilla was significantly higher in the 0.15% tannin group than in the 0.45% tannin group(P<0.05);the thickness of the ileal muscle layer was significantly higher in the 0.15% tannin and control groups than in the 0.3% tannin and 0.45% tannin groups(P<0.05);the α-amylase and cellulase activities in the rumen were significantly higher in the 0.15%tannin group than in the 0.45% tannin group(P< 0.05),the changes of α-amylase,lipase,chymotrypsin and trypsin in duodenum and ileum were not significant in control and test groups(P>0.05);cellulase and β-glucosidase in cecum were significantly higher in 0.15% tannin group than in 0.45% tannin group(P<0.05);lipase activity in 0.15% tannin group was significantly higher than in control and 0.3% and 0.45% tannin group(P<0.05).3.In the Alpha diversity results,it can be seen that the rumen Ace index and Chao index in the 0.15%tannin group were significantly higher than those in the 0.45% tannin group(P < 0.05);Shannon index and Simpson index were not significantly different between groups(P > 0.05);the Ace index of the cecum in the 0.15% tannin group was significantly higher than those in the control and 0.45% tannin groups(P<0.05);the Chao index was significantly higher in the 0.3% tannin group than in the control and 0.45%tannin groups(P < 0.05);the Shannon and Simpson indices did not differ significantly between groups(P >0.05);tannin addition did not have a significant effect on the relative abundance of microbiota levels in the rumen and cecum of sheep(P > 0.05);Prevotella spp.genus 7(Prevotella＿7)in the 0.3% tannin group was significantly higher than that in the 0.45% tannin group(P < 0.05);the addition of tannin to the sheep ration had no significant effect on the level abundance of the cecum genus(P > 0.05).Conclusion:In conclusion,the addition of tannins to the diet at 0.15% and 0.3% had positive effects on growth performance,antioxidant properties of jejunal mucosa,gastrointestinal tract tissue morphology and gastrointestinal digestive enzyme activity in sheep,while the addition of tannins to the diet changed the structure of gastrointestinal bacterial flora,and appropriate doses of tannins had positive effects on the gastrointestinal health of sheep.