Gut Bacterial Diversity Investigation And Rumen Metabolites Profiling Of High Production Dairy Cows

The rumen bacteria is an essential part of ruminants shaping their nutrition and health.Gut microbiota has been defined as an organisms’ second genome,affecting the metabolic phenotype and production traits of the host.In this study our aim was to simultaneously investigate the rumen fluid bacterial typical characteristic and conduct rumen metabolites profiling of high production dairy cows.In the first part,we selected 22 Holstein dairy cows with 11 high production cows and 11 low production cows paired under the same diet regimes,feeding environment,age,parity and nearing lactation days.The bacterial differences of rumen fluid and feces were identified by 16 S rDNA gene sequencing.The metabolites differences were identified by metabolomics profiling with liquid chromatography(LC)-mass spectrometry(MS).Compared to rumen fluid of low production cows,the high production cows increased the abundance of phylum Proteobacteria and decreased the abundance of phylum Bacteroidetes,SR1,Verrucomicrobia,Euryarchaeota,Planctomycetes,Synergistetes and Chloroflexi significantly(P<0.05).There was none a phylum showed obvious difference between feces bacteria flora of the two groups.At the genus level,the rumen fluid of high production group was enriched for Butyrivibrio,Lachnospira and Dialister significantly(P<0.05).Meanwhile,rumen fluid of high production group was depleted for Prevotella,Succiniclasticum,Ruminococcu,Coprococcus,YRC22,CF231,02d06,Anaeroplasma,Selenomonas and Ruminobacter significantly(P<0.05).Compared to fecal bacterial flora of low production cows,the feces of high production cows increased the abundance of 5-7N15,Dorea,Sutterella and Anaeroplasma significantly(P<0.05).A total of 92 discriminant metabolites were identified between high-production cows and low-production cows.Compared to low-production dairy cows,10 differential metabolites were found up-regulation in high-production dairy cows,including6alpha-Fluoropregn-4-ene-3,20-dione,3-Octaprenyl-4-hydroxybenzoate,disopyramide,compound III(S),1,2-Dimyristyl-sn-glycerol,7,10,13,16-Docosatetraenoic acid,ferrous lactate,6-Deoxyerythronolide B,vitamin D2 and L-Olivosyl-oleandolide.The remaining other 82 differential metabolites were found to be obviously down-regulated in high production cows.Metabolic pathway analyses indicated that most increased abundance ofrumen fluid metabolites of high-yield cows were related to metabolic pathways involving biosynthesis of unsaturated fatty acids,steroid biosynthesis,ubiquinone and other terpenoid-quinone biosynthesis.Most down-regulated metabolic pathways were relevant to nucleotide metabolism,energy metabolism,lipid metabolism and biosynthesis of some antibiotics.In the second part,we each choose six healthy Laoshan milk goat,six healthy Luxi Huangniu and five healthy Bohai Heiniu.The bacterial differences of rumen fluid were identified by 16 S rDNA gene sequencing.Then we choose six pair of high production and low production dairy cows in the first part together with Laoshan milk goat,Luxi Huangniu and Bohai Heiniu to conduct data analysis.Generally speaking,the rumen fluid bacterial diversity of high production dairy cows was obviously different with milk goat,Huangniu and Heiniu.But there was a similar bacteria flora between the rumen fluid of Huangniu and Heiniu.At phylum level,the high production dairy cows increased the abundance of Proteobacteria,Spirochaetes,Cyanobacteria and decreased the abundance of Firmicutes,Tenericutes,Verrucomicrobia,Euryarchaeota,Chloroflexi,Actinobacteria and Lentisphaerae significantly(P<0.05).At genus level,the rumen fluid of high production group significantly increased the abundance of Treponema,Butyrivibrio,Coprococcus,Shuttleworthia,Lachnospira and Selenomonas(P<0.05)compared to milk goat,Huangniu and Heiniu.On the other hand,the rumen fluid of high production group significantly decreased the abundance of genera CF231,02d06,Oscillospira,RFN20,Desulfovibrio,Methanobrevibacter and SHD-231(P<0.05).Besides,there were other mutual genera in the fluid of Huangniu and Heiniu simultaneously indicated marked abundance differences when compared to high production dairy cows.In general,significant bacterial differences were presented between the fluid of high production and low production dairy cows which were mainly reflected by the relative abundance of some special bacteria.Furthermore,there existed significant metabolic differences between the two groups as well.In addiition,significant bacterial differences were also presented between the fluid of high-yield dairy cows and the fluid of Laoshan milk goat,Bohai Heiniu and Luxi Huangniu.