BVD virus isolation techniques for routine use in cattle herds with or without previous BVD history.

Buffy coats of 1074 cattle were tested for BVD virus using the usual longterm-cultivation (LTC) in bovine kidney monolayer cell cultures (7 days) whereby 268 BVD virus carriers could be detected. Serum samples collected simultaneously from the same animals were examined by means of a shortterm-cultivation (STC) procedure of only two days in stationary macroplate cell cultures. Using this method only 172 amongst the former 268 BVD virus carriers were found. Of the remaining 96 serum samples from animals positive in buffy coats leucocytes by LTC and negative in sera by STC, further 19 cattle were found to be viraemic when the sera were additionally tested by LTC. These results are discussed with regard to the antibody level and the age of the animals. The reduced sensitivity of STC of sera is considered in relation to the favourable time and cost factor. STC of serum samples in connection with the serological results on a herd basis proved to be valuable for the examination of cattle of more than 6 months of age but not for calves below 6 months. This was particularly true in cattle herds with no previous BVD history.