Bovine viral diarrhoea virus (BVDV) is an important pathogen of dairy cattle. In this study, bulk milk samples representing a total of 4105 milking cows, from 18 dairy cattle herds in the suburb of Mashhad- Iran, were tested for presence of BVDV by the use of a nested reverse transcription polymerase chain reaction (Nested RT- PCR) assay. Non of the cows in the herds had been vaccinated against BVDV. RNA was extracted from somatic cell pellets of bulk milk tank samples. Oligonucleotide primers were selected based on the 5´ untranslated region of the BVD virus genome. BVD virus was detected in 2 (11.1%) out of 18 samples, representing 742 lactating cows. These results indicate that nested RT-PCR analysis of bulk milk samples may provide a rapid and sensitive screening method for the detection of BVDV infections in non-vaccinated dairy cattle herds.

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