ABSTRACT
This study was done on 1134 cattle present in five private dairy cattle farms at Behera governorate. 823 animals were apparently healthy while 311 ones showed one or more of the following signs, fever, bloody diarrhea, dehydration, cough, nasal discharges, oral lesions and/or bilateral corneal opacity. Serum samples were collected from all animals, also 148 Buffy coat samples, 160 nasal swabs and 163 fecal swabs were collected from diseased animals. These samples were taken at autumn and winter seasons. From 1134 animals, 828 animals were vaccinated against BVD and IBR while 306 animals were not vaccinated. All serum samples [1134] were subjected to serum neutralization test [SNT], [47.7%, and 42.1%] of non vaccinated animals and [63%, 48.7%] of vaccinated animals showed antibodies against BVDV and IBR, respectively. BVDV was isolated from [24.1%, 14.3%, and 11.7%] and [21%, 25.3%, 16.3%] of Buffy coat samples, nasal swabs and fecal swabs from non vaccinated and vaccinated animals respectively. IBR was isolated from [17.2%, 9%, 51%] and [21%, 24%, 13.9%] of Buffy coat samples, nasal swabs and fecal swabs from non vaccinated and vaccinated animals respectively. From the obtained results we can conclude that bovine viral diarrhea and infectious bovine rhinotracheitis viruses are prevalent in many dairy cattle farms in Behera governorate. Also vaccination of late pregnant animals only is not sufficient to prevent persistent BVDV infection and vaccination against BVD and IBR viruses shall be done before conception to prevent the occurrence of persistent BVD infection and it can be repeated before parturition to protect the newly born calves from infection