The Effects Of High-grain Diet On Ruminal And Colonic Fermentation,Microbial Community And Epithelial Morphology Of Goats

Ruminal subacute acidosis has been widely paid attention and studied.Recent years,hindgut acidosis also drew people’s attention.The present study compares the fermentation of rumen and colon with different proportion of grain diet.Furthermore,we study the effect of high-grain diet on the ruminal and colonic fermentation,microbial composition and morphology in goats.1.Comparison of the effects of substrates with different percentages of grain on the ruminal and colonic fermentation in vitroThis study aimed to investigate the effects of substrates with different percentages of grain on the colonic and ruminal fermentation in vitro.Three different proportions(0%:A0,35%:A0.35 and 60%:A0.6 of grain)in substrates.The results showed that the total gas production of rumen and colon increased with the increasing proportion of grain in substrates(P<0.05).Moreover,the gas produced in rumen was higher than that in colon with the same substrate.The concentrations of acetate,propionate,valerate and total VFA in colon are lower than that in rumen(P<0.05);the ratio of acetate to propionate in colon is higher than that in rumen(P<0.001).With the increase of grain proportion,isovalerate in colon is lower than that in rumen,and the concentration of butyrate became higher than that in rumen.Compared with rumen,the proportion of butyrate in colon is higher and the proportion of propionate is lower.There was no significant difference(P>0.05)in pH value between Ak,A0 and A0.6 groups.However,the difference of pH value in A0.35 group between rumen and colon is significant(P<0.05).In general,the effects of different concentrate on ruminal and colonic fermentation are different and the ruminal microbial fermentation was more active compared with the colonic microbiota.2.The effect of high-grain diet on ruminal fermentation,epithelial microbial community and epithelial morphology of goats.High-grain(HG)diet feeding has been shown to be related with the local inflammation in rumen of ruminants.However,remarkably little information is available about the changes in the epithelial microbial community and its relationship with cytokines mRNA expression during HG diet feeding.Thus,the objective of the present study was to evaluate the effect of grain-rich diet on the ruminal fermentation,ruminal epithelial microbial community,epithelial morphology and inflammatory cytokines mRNA expression in goats.Twelve male goats were randomly assigned to two groups based on whether they were fed a hay diet(HAY;0%grain;n = 6)or a HG diet(HG;65%grain;n = 6).Our results showed that the high-grain diet altered the ruminal fermentation characteristics and the ruminal epithelial bacterial community.A total of 203 genera were detected and 21 phyla exhibited significant variability across diets.Relative abundance of dominant genera unclassified Clostridiales and Prevotella were significantly increased by feeding HG diet.In contrast,there is a corresponding decrease in the proportion of Shuttleworthia,unclassified Ruminococcacea,Fibrobacter and unclassified Neisseriaceae.32.99%,10.76%and 56.25%of total OTUs were detected in Hay only,in HG only and in both diets,respectively.Furthermore,HG diet feeding changed the gene expression of IL-1β(P = 0.008)and IL-6(P = 0.011)significantly when compared to the hay group,while there was no significant difference in the relative mRNA expression levels of IL-2,IL-10,IL-12,IFN-γ and TNF-a between the hay group and HG group.In conclusion,these results demonstrated that the HG diet feeding caused a strong shift in ruminal epithelial bacterial community and resulted in local inflammation.3.The effect of high-grain diet on colonic fermentation,mucosal microbial community and mucosal morphology of goats.Remarkably little information is available about the impact of high-grain(HG)feeding on colonic mucosa-associated bacteria and mucosal morphology.In the present study,12 male goats were randomly assigned to either a hay diet(n = 6)or an HG diet(65%grain;n = 6)to characterize the changes in the composition of the bacterial community in colonic mucosa and the mucosal morphology of the colon.The results showed that HG feeding decreased the colonic pH(P = 0.003)and increased the concentrations of total short chain fatty acids and lipopolysaccharides in colonic digesta(P<0.05).The principal coordinate analysis results showed that the HG diet altered the colonic mucosal bacterial communities,with an increase in the abundance of genus Blautia(P = 0.006)and a decrease in the abundance of genera Bacillus,Enterococcus,and Lactococcus(P<0.05).The HG-fed goats showed sloughing of the surface layer epithelium,intercellular tight junction erosion,cell mitochondrial damage,and upregulation of the relative mRNA expression of IL-2 and IFN-γ in colonic mucosa(P<0.05).Collectively,our data indicate that HG feeding induced changes in colonic mucosal morphology and cytokines expression that might be caused by excessive fermentation and dramatic shifts in the bacterial populations in the colon.