Bovine virus diarrhoea virus in semen from acutely infected bulls.

The risk of spreading bovine virus diarrhoea virus (BVDV) from acutely infected animals to susceptible animals was investigated. Ten bulls from a herd with no previous history of BVDV were used. The bulls were demonstrated free from BVDV and such antibodies. Six of the bulls were inoculated intravenously with cytopathogenic virus, and 4 bulls were used as controls. Semen samples were collected during a period of 66 days after inoculation. The samples were examined for BVDV, and spermatological parameters were registered. Testes and epididymides were examined histologically post mortem. All inoculated bulls exhibited elevated temperatures between days 4 and 8 after inoculation, and BVDV antibodies were found in all of them on day 22. The control animals remained antibody negative. Non-cytopathogenic BVDV was isolated from seminal plasma from 2 bulls on day 7 after inoculation. Semen volume was significantly reduced from week 6 after inoculation. Percent abnormal sperm cells decreased in the same period. No significant differences were observed in sperm density or percentage of live spermatozoa. No pathological changes were found in the testes or epididymides.