The Impact Of High Grain Diets On Rumen Microbiota And Metabolites In The Rumen Fluid,Serum,Liver In Goats

In ruminants industry,long-term high-grain diet feeding results in rumen microbial flora imbalance,metabolic disorders,impairs animal health,and causes economic loss.We have found that long-term diet feeding resulted in the damage of rumen epithelial and changes of the rumen environment,and the objectives of this paper was to investigate the impact of high-grain diet feeding on bacterial composition associated with rumen fluid and rumen epithelium,and was to explore the changes in metabolites of rumen fluid,liver and blood during high-grain feeding which allows us to make sure the mechanisms of metabolomics relating to host health during high-grain feeding in goats,and provides a theoretical basis for the research of ruminant health.1 Effect of high-grain diet on rumen microbiota in goatsThis study was designed to study the influence of high-grain diet feeding on bacterial diversity and composition in rumen fluid of goats.Ten ruminally fistulated,castrated male goats were randomly assigned to either a hay diet(0%grain;n=5)or high-grain(HG)diet group(65%grain;n = 5)with continuous feeding of 7 weeks.On day 50,a representative sample of rumen digesta(at least 200 ml)was used to determine the pH value and was then strained through 4 layers of cheese cloth to assess changes in bacterial composition in rumen fluid using bar-coded 454-pyrosequencing techniques.The results showed that HG diet feeding decreased the diversity of bacterial community in rumen fluid significantly(P<0.05);HG feeding increased percentage of amylolytic bacteria,such as Selenomonas,Succiniclasticum,Ruminococcus and unclassified Veillonellaceae(P<0.05),while decreased the relative abundance of Butyrivibrio,unclassified Lachnospiraceae,unclassified Rikenellaceae,unclassified Erysipelotrichaceae,unclassified Ruminococcaceae and unclassified Mollicutes(P<0.05).Furthermore,Principal component analysis showed that ruminal bacterial composition of HG group were significant different from that of hay group.The results indicated that HG feeding affected diversity and composition of bacterial community in rumen fluid,caused disorder of bacterial flora in rumen,and impaired the health of ruminants.2 Effect of high-grain diet on rumen epithelial bacterial in goatsThe high-throughput sequencing technique was used to study the effect of HG diet feeding on rumen epithelial bacterial composition in this experiment.On day 50,ten goats were slaughtered,then rumen epithelial tissue was collected immediately and used for high-throughput sequencing analysis to evaluate the difference of rumen epithelial microflora composition between hay and HG group.The results showed that HG diet feeding caused dramatic changes in rumen epithelial bacterial composition;at the genus level,HG diet feeding increased the relative abundance of Butyrivibrio,unclassified Clostri diales,Mogibacterium,unclassified Anaerolineaceae,Succiniclasticum and Ruminococcus significantly(P<0.05),however,the relative abundance of Howardella,unclassified Ruminococcaceae,unclassified Neisseriaceae,unclassified Rikenellaceae and unclassified Erysipelotrichaceae showed a lower percentage in HG group(P<0.05).The research indicated that HG diet feeding caused a drop in pH in the rumen,perturbing the bacteria associated with ruminal epithelium.3 GC-MS metabolomics analysis of metabolites in rumen fluid,liver,and serum following high-grain diets in goatsThe purpose of this experiment was to observe the changes of metabolites in rumen,liver and serum during HG feeding in goats.On day 50,rumen fluid,liver and peripheral blood samples were collected for GC-MS analysis.The results showed that there were 84,83 and 69 kinds of metabolites detected in the rumen fluid,liver and serum;according to the results of PCA and PLS-DA score plot,the metabolites in HG group were separated from hay group;combining PLS-DA analysis with independent sample T-test,we found that there were 12,10 and 9 kinds of metabolites separated significantly between hay and HG group in rumen fluid,liver and serum(VIP>1.3;P<0.05),these significant different metabolites mainly involved in amino acid metabolism and glucose metabolism;HG group occupied a higher concentrations of abnormal metabolites,such as putrescine and LPS;The quantitative real-time PCR results showed that the relative expression of IL-10 in the HG group tended to increase(0.05<P<0.10).These results indicated that HG diet feeding impaired rumen metabolism,increased the concentrations of toxic or anti-inflammatory cytokines,and finally affected amino acids and glucose metabolism.These findings indicated that high-grain diet feeding changed the contents of metabolites in goats,causing metabolism disorder,eventually,imposing a threat on ruminants health.