Analysis Of Vaginal Bacterial Composition In Dairy Cows With Metritis Based On 16S RDNA Sequencing Method

Metritis is the frequently occurring diseases in dairy cows and one of the important reason of infertility in dairy cows,accounts for 20%?30%of dairy cow diseases,has serious implications for cattle industry.It has been reported in the literature that the balance of vaginal flora are directly related to maintain normal physiological function and the reproductive system of various disease development.To clear the vaginal flora abundance and diversity of dairy cows in healthy and metritis by 16SrDNA sequencing method,providing a new way for further explorations of metritis mechanism so that providing foundations of prevention and treatment in metritis of dairy cows.Selecting 10 dairy cows respectively from formative period(12 months of age),gestation period(7 days before labor),postpartum period(40 days after labor)and metritis(20 days after labor)Holstein dairy cows in the present study.The superior certain side of the external cervical os was smeared with the sampler thoroughly.By 16S rDNA sequencing technology,678,043 clean tags were obtained,the number of the VY,VP,VH and VI group is 1548?1264?1153 and 265 respectively,the coverage of all samples was higher than 98%,shannon index figure showed that our rarified sequencing depth was sufficient to evaluate the diversity in the dairy cows vaginal samples determined in the present study.The results of this research find that at the phylum,class,order,family,genus level,three health set of samples of the top 10 bacteria are the same:the highest levels of phylum is Firmicutes,class is Clostridia,order is Clostridiales,family is Ruminococcaceae,while the genus level has a bigger difference.The highest levels of phylum type clinical metritis group is Bacteroidetes and class is Bacteroidia,order is Bacteroidales,family is Porphyromonadaceae,genus is Porphyromonas.The results showed that the bacterial abundance formative period and gestation period was similar,there is difference in gestation and postpartum period.Compare with gestation and postpartum period,the bacteria community was more complex in formative period,there are many special bacteria existed with low abundance.The vaginal bacterial abundance of VI group was different with healthy groups:the highest relative abundance of bacterial disease group is Bacteroidetes,low is Firmicutes and Proteobacteria.Postpartum healthy controls the highest relative abundance of bacteria was Firmicutes,lower Bacteroidetes and Proteobacteria.In the ? group,the content of Xanthomonadales,Ruminococcaceae,and Ruminococcaceae-UCG-005 is 0.10%,0.31%and 0.10%respectively,and the VH group content is 7.56%,7.56%and 30.27%respectively;Porphyromonas(44.41%)and Fusobacterium(12.13%)as the main species in VI group,and the content of this genus were 1.37%and 4.67%respectively in VH group,indicating that Porphyromonas and Fusobacterium were the main pathogenic bacteria for clinical metritis in dairy cow vagina.The present study shows that,vaginal bacterial diversity in different physiological phases of cows was rich,Firmicutes and Proteobacteria was the predominant phylum represented.Pregnancy had little effect on the vaginal bacterial community;however,the abundances of vaginal pathogens increased in postpartum cows.Vaginal bacterial diversity decreased in cows with metritis,and the predominant genera of bacteria are Porphyromonas and Fusobacterium.