Epidemiological Investigation,vaginal Bacterial Microbiota Analysis And Clinical Treatment Of Endometritis In Dairy Cows In Zhangye Based On VDS

Endometritis is one of the main reproductive system diseases that affects the healthy development of dairy cow breeding industry.It can lead to the decline of pregnancy rate,the increase of breeding times,the extension of day open,the increase of pregnancy risk and the decline of milk production.In serious cases,it can lead to the loss of fertility of dairy cow,increase the elimination rate and affect the healthy development of dairy industry.The prevalence of this disease is increasing in China,showing a regional difference.The epidemic is related to pathogen infection,own hormone level,secondary factors,environmental hygiene,feeding management and other factors.As an important micro-ecological area in the reproductive system of dairy cows,the vagina plays an important role in preventing pathogens from invading the uterus.However,we know very little about the dynamic changes of vaginal flora in dairy cows with endometritis in different postpartum periods.It is generally believed that bacteria are the main cause of endometritis in dairy cows.Clinically,antibiotics are commonly used to inhibit or eliminate uterine pathogens.However,the large-scale use of antibiotics can easily cause bacterial resistance and drug residues in raw milk,which is not conducive to biological safety and food safety.Therefore,it is necessary to investigate the prevalence of endometritis in dairy cows in a region,explore the composition of vaginal flora in dairy cows with endometritis in different postpartum periods,and screen a new rotating drug to provide theoretical basis and scientific reference for the prevention and treatment of this disease.This study mainly included the following three parts.Part Ⅰ: Epidemiological investigation of clinical endometritis(CE)in dairy cows.The VDS grading system was used to investigate the prevalence of CE in 803 dairy cows at 26 ± 3 days in milk(DIM),and the influence of secondary factors such as calving season,parity and body condition score(BCS)on CE of dairy cows was analyzed.The incidence rate of CE in 803 cows was 33%,of which mild endometritis(VDS 1)was 12.9%,moderate endometritis(VDS 2)was 10.8%,severe endometritis(VDS 3)was 9.3%.The morbidity was high in January,June,July,August and December throughout the year(P < 0.05);the morbidity of CE in multiparous dairy cows was 1.765 times that of primiparous dairy cows(P < 0.001);BCS had no effect on cow endometritis(P > 0.05).Part Ⅱ: Analysis of vaginal flora in different postpartum periods of dairy cows with endometritis.The vaginal discharge of 39 healthy cows(VDS 1)at 14 days postpartum and cows with endometritis(VDS 2-3)at 21,28,35 and 42 days postpartum were collected.The sequence of microbial 16 S r DNA V4 region in the vagina of healthy cows at 14 days postpartum and cows with endometritis at 21,28,35 and 42 days postpartum were determined by 16 S r DNA high-throughput sequencing technology(Illumina Hi Seq).The community structure and diversity of vaginal flora in healthy dairy cows and diseased dairy cows at different periods of postpartum were compared,and its correlation with the occurrence of endometritis was analyzed.A total of 18 known phylum and 231 known genera were identified.The composition of vaginal flora of healthy cows at 14 days postpartum and dairy cows with endometritis at 21,28,35 and 42 days postpartum showed diversity,but there were differences in similarity.Firmicutes was the dominant phyla in the vagina of healthy dairy cows 14 days postpartum,and Streptococcus was the dominant genus in the vagina of healthy dairy cows.Bacteroidetes and Proteobacteria were the common dominant bacteria phyla in the vagina of dairy cows suffering from endometritis at 21,28,35 and 42 days postpartum,and Bacteroides was the main bacteria genus in diseased dairy cows at different postpartum periods.Part Ⅲ: Evaluation of the clinical effect of hypertonic dextrose solution in the treatment of dairy cow with endometritis.After diagnosis by VDS system,45 cows with moderate endometritis(VDS 2)and 38 cows with severe endometritis(VDS 3)were treated with intrauterine infusion of 200 m L of 50% dextrose solution at 26 ± 3days postpartum.The clinical therapeutic effect of dextrose solution and the reproductive performance of first AI pregnancy rate,days to first AI,days open,service per pregnancy and conception rate at 200 days postpartum were evaluated.After 14 days therapy,the cure rates of VDS 2 and VDS 3 were 73.3% and 71.1%,respectively,which were higher than those of untreated cows(P < 0.05),and the treatment effect was obvious.The reproductive performance of first AI pregnancy rate,days open and pregnancy rate at 200 DIM were significantly improved,which were higher than those of untreated dairy cows(P < 0.05),and were close to the reproductive performance of healthy dairy cows(VDS 0).