[Bovine virus diarrhea (BVD)--diagnostic determination of cattle with persistent BVD virus infection].
Buffy coats of 1074 cattle were examined for regard to BVD virus using the usual long-termed-cultivation (LTC) in bovine kidney monolayer cell cultures (7 days) whereby 268 carriers could be detected. Serum samples collected simultaneously from the same cattle were examined by means of a short-termed-cultivation (STC) of only two days in stationary macroplate cell cultures. Using this method only 172 carriers were found. Amongst 96 serum samples from animals positive in LTC of buffy coat leucocytes and negative in the STC further 19 cattle were found to be viraemic when the sera were tested by LTC, too. Thus 77 of a total of 268 serum samples (28.7%) taken from viraemic cattle turned out to be negative in the STC as well as the LTC. These results are discussed with regard to the antibody level and the age of the animals. The reduced sensitivity is considered in relation to the favourable time and cost factor. STC of serum samples in connection with the serological results proved to be valuable for the examination of cattle of more than 6 months of age but not for calves below 6 months.