Effects Of Different Crude Feed Fiber Sources On Rumen Fermentation And Microbial Community Structure In Vitro

This experiment used in vitro fermentation to study the effects of neutral detergent fiber(NDF)or acid detergent fiber(ADF)from five different roughage sources(straw,corn stover,alfalfa hay,whole-plant corn silage and oat grass)on rumen fermentation,cellulase activity,bacterial flora and fiber-degrading bacteria.The test results are as follows:Experiment 1:The effect of NDF and ADF from different roughage sources on rumen fermentation in vitro.Taking NDF and ADF from different roughage sources as the research objects,there was no significant difference in the pH of rumen fermentation liquid in vitro between the NDF and ADF groups of different roughage sources,but there were significant differences in the concentrations of ammoniacal nitrogen and microbial protein;There were significant differences in the concentration of volatile fatty acids in the rumen fermentation liquid of the NDF group of different roughage sources in vitro,but the effects of ADF of different roughage sources did not show significant differences.Taking NDF and ADF from the same roughage source as the research objects,generally speaking,the removal of hemicellulose will increase the pH of rumen fermentation liquid in vitro and reduce the concentration of volatile fatty acids,ammonia nitrogen and microbial protein.Experiment 2:The effect of NDF and ADF from different roughage sources on cellulase activity in vitro.Taking NDF and ADF from different roughage sources as the research objects,the activity of carboxymethylcellulase and β-glucosidase in the rumen fermentation liquid of the NDF group of different roughage sources was significantly different;There were significant differences in the activity of Avicelase and β-glucosidase in the rumen fermentation liquid of different roughage sources ADF groups in vitro.Taking NDF and ADF from the same roughage source as the research objects,the cellulase activity in the rumen fermentation liquid of the ADF groups from five roughage sources was higher than that of the NDF group.Experiment 3:The effects of NDF and ADF from different roughage sources on the rumen bacterial flora structure and fiber-degrading bacteria in vitro.Taking NDF and ADF from different roughage sources as the research objects,based on the phylum level classification,the predominant bacterial groups in the rumen fermentation liquid of the NDF group of different roughage sources were Proteobacteria，Firmicutes and Bacteroides,There are significant differences in species diversity and species composition structure between NDF group of different roughage sources;The predominant bacterial groups in the rumen fermentation liquid of the ADF group of different roughage sources in vitro were Proteobacteria，Firmicutes,Fusobacteria,and Bacteroidetes.The diversity of their species did not show significant differences,but there was a certain difference in the structure of the flora.Taking NDF and ADF from the same roughage source as the research objects,The species diversity in the rumen fermentation liquid in vitro in the NDF group of different roughage sources was higher than the ADF group.based on the phylum level classification,the microbial structure in the rumen fermentation liquid in vitro also showed significant differences.In summary,NDF,ADF from different roughage sources and NDF,ADF from the same roughage sources have different effects on rumen fermentation,cellulase activity and rumen bacterial diversity,flora structure,and relative abundance of fiber-degrading bacteria.The test results help us understand the degradation characteristics of NDF and ADF from different sources of roughage in the rumen of dairy cows,and also help us to explore the influence of fiber from different sources of roughage on the structure of rumen bacterial flora.