Patterns Of Uterine Infection In Dairy Cows In Some Areas Of Ningxia And Identification Of Bacterial Isolation And Analysis Of Bacterial Flora Structure

Cow metritis is a kind of reproductive disorder frequently occurring in postpartum daily cows,which seriously affects the reproduction and production performance of dairy cows and brings huge economic losses to the dairy farming industry.In order to understand the incidence in postpartum metritis of dairy cows and the types of pathogenic bacteria causing uterine infection in Ningxia.In this study,the incidence of postpartum metritis of dairy cows was investigated in five regional large-scale dairy farms in Ningxia.The uterine contents of infected cows were collected for the isolation and purification of bacteria.Gram staining and bacterial 16S rRNA sequencing were used by identified the bacteria species,and drug susceptibility tests were performed for the main pathogenic bacteria that may cause cow metritis.Finally,the structural changes in the uterine microflora of healthy and diseased dairy cows were analyzed to provide a scientific basis for the clinical prevention and treatment of postpartum metritis of dairy cows.The results of this study were as follows:1.The average incidence of postpartum metritis dairy cows in five regions of Ningxia was 13.07%,among which the annual incidence of cow metritis in farm A of Qingtongxia City,farm B of Yinchuan City,farm C of Huinong District,farm D of Pingluo County and farm E of Lingwu City were 6.94%,14.77%,15.32%,10.29%and 13.76%,respectively;overall,the average incidence of cow metritis was the highest from August to September,about 28.22%,and the lowest from January to May,about 16%.From January to August,the incidence of cow metritis showed an increasing trend,and from September to December there was a decreasing trend.The incidence of cow metritis was highest in 3-pregnant cow and 4-pregnant cows,about 16.59%and 16.44%,respectively,and the incidence of cow metritis was higher in first-pregnant cows than in 2-pregnant cows;from the 5th pregnant cows,the incidence of metritis decreased gradually with the increase of parities.The incidence of retained placenta,ketosis,mastitis and digestive diseases in postpartum cows accounted of cow metritis for 22.75%,14.66%,4.13%and 7.86%,respectively.2.In this study,a total of 32 species of bacteria were isolated from the uterine contents of 88 postpartum metritis dairy cows,among which 28 were aerobic and compositive anaerobic bacteria,mainly Escherichia coli from Proteobacteria and Bacillus Firmicutes.There were four types of strict anaerobic bacteria,mainly Streptococcus anaerobius in Firmicutes,Prevotella melaninogenica in Bacteroidetes,Fusobacterium necrophorum and Clostridium perfringens in Fusobacteria.There were some differences in the distribution of pathogenic bacteria in cow metritis in the five regions,including 14 kinds in A farm of Qingtongxia City,7 kinds in B farm of Yinchuan City,12 kinds in C farm of Huinong District,16 kinds in D farm of Pingluo County,and 9 kinds in E farm of Lingwu City.Infections of pathogenic bacteria in cow metritis are both mixed and single infections,but mainly mixed infection.The results of drug sensitivity test showed that the pathogenic bacteria had low sensitivity to penicillin,streptomycin,cotrimoxazole and lincomycin,but high sensitivity to cefotaxime,cefalexin,Enrofloxacin and ofloxacin,etc.3.The results of bacterial 16S rDNA sequencing showed that at the phylum level,compared with the healthy group,the relative abundance of Bacteroides in the pathogenic group was extremely significantly increased(P<0.01),the relative abundance of Fusobacterium was significantly increased(P<0.05),while the relative abundance of Proteobacteria was extremely significantly decreased(P<0.01).At the genus level,compared with the healthy group,the relative abundance of Porphyromonas,Bacteroides,Fusobacterium and Peptostreptococcus in the disease group was extremely significantly increased(P<0.01),while the relative abundance of Acinetobacter was extremely significantly decreased(P<0.01),and the relative abundance of Chryseobacterium was significantly decreased(P<0.05).At the species level,compared with the healthy group,the relative abundance of Porphyromonas levii,Fusobacterium necrophorum,Bacteroides pyogenes and Peptostreptococcus anaerobius in the disease group was extremely significantly increased(P<0.01),and the relative abundance of Escherichia coli was significantly increased(P<0.05).In summary,the occurrence of postpartum metritis dairy cows in five regions of Ningxia was mainly concentrated in August to September,in 3-pregnant and 4-pregnant cows,which was mainly caused by multiple infections of pathogens such as Fusobacterium necrophorum in Fusobacteria,Escherichia coli in Proteobacteria,porphyromonas and Bacteroides pyogenes in Bacteroidetes.Most pathogenic bacteria have developed resistance to penicillin,streptomycin,cotrimoxazole and lincomycin,while drugs such as cefotaxime,cefadroxil,enrofloxacin and ofloxacin are the best treatment drugs for cow metritis.