Epidemiological Investigation And Prevention Of IBR And BVD Of Dairy Cows In Ningxia

Infectious bovine rhinotracheitis(IBR)and bovine viral diarrhea(BVD)are a kind of acute,febrile,and contact bovine infectious rhinotracheitis virus(IBRV)and bovine viral diarrhea virus(BVDV)respectively.infectious disease.IBRV mainly causes fever in cattle,severe upper respiratory symptoms,miscarriage of cows,stillbirth,and inflammation of the reproductive tract and calf encephalitis.BVDV mainly causes symptoms such as fever,mucosal ulceration,diarrhea and abortion in cattle.China classifies IBR and BVD as Class ? and Class ? animal diseases respectively.At present,these two infectious diseases are widespread in our country,they cause significant economic losses to the breeding industry.In this study,serological and molecular biology methods were used to conduct epidemiological investigations on IBR and BVD of large-scale dairy farms in four regions of Ningxia,and a preliminary understanding of the epidemic situation of these two infectious diseases in Ningxia.Carried out immunization prevention experiments and pasture prevention and control practices,and summarized the prevention and control measures for IBR and BVD.The specific research results are as follows:1.Enzyme-linked immunosorbent assay was used to detect antibodies against IBRV and BVDV in 1,446 bovine serums from 45 dairy farms in 4 regions of Ningxia.The results showed that the antibody positive rates of IBRV and BVDV in cattle herds in Ningxia were 82.36%and 86.03%,respectively.IBRV has the highest antibody positive rate reaching 86.91%in Wuzhong area,and the lowest positive rate is 76.27%in Shizuishan area;BVDV has the highest antibody positive rate reaching 90.41%in Yinchuan area,and the lowest positive rate in Shizuishan area,which is 80.00%.ELISA test results in different seasons showed that the antibody positive rates of IBRV and BVDV were the highest in winter,they are respectively 88.31%and 91.40%,while the positive rates were the lowest in summer,they are respectively 75.33%and 79.67%.The antibody positive rates of IBRV in calves,young cattle,and adult herds were 78.92%,73.77%and 86.2%respectively;the antibody positive rates of BVDV in calves,young cattle,and adult herds were 78.51%and 83.93%and 88.76%respectively.2.Using fluorescent PCR method,nasal swabs and anal swabs of 592 dairy cows in 4 regions of Ningxia were tested for nucleic acid of IRV and BVDV.The results showed that the average positive rate of IBRV for dairy cows in Ningxia was 2.03%;the average positive rate of BVDV was 2.70%.IBRV was 3.13%which was the highest positive rate in Wuzhong area;BVDV has the highest positive rate reaching 3.44%in Zhongwei area.The test results of different seasons show that IBR is most prone to occur in autumn and BVD is most prone to occur in winter.The detection of dairy cows at different growth stages showed that the positive rate of IRV was 2.89%which was the highest in the calf herd,and the positive rate of BVDV was 3.94%the highest in the young herd.3.The IBR and BVD antibody-positive and negative pregnant cows were injected with IBR-BVD combined inactivated vaccine 60 days and 30 days before the expected date of delivery,and the changes of antibodies were detected by ELISA before and after immunization.The results showed that after the cattle were injected with the dual inactivated vaccine,the immune antibody level of the cattle increased significantly,and the maternal antibody of the calves born to pregnant cows increased significantly.Comprehensive prevention and control of IBR and BVD were carried out in a ranch,and the incidence of related diseases was counted before and after prevention and control.It was found that the implementation of comprehensive prevention and control can significantly reduce the incidence of bovine infectious rhinotracheitis and bovine viral diarrhea in the herd.In summary,IBR and BVD are widely prevalent in dairy herds in Ningxia,and there are significant differences in infection in different regions,different seasons,and different age groups.By eliminating pathogen-positive cattle,injecting IBR-BVD combined inactivated vaccine,strengthening feeding management,disinfection and other comprehensive prevention and control measures,the incidence of IBR and BVD in the herd can be significantly reduced.