Twelve (Experiment I) and four (Experiment II) multiparous dairy cows seronegative to pestivirus were
selected and randomly assigned to either a control group which did not become infected or a treatment
group in which all cows became infected following intranasal inoculation 9 days before AI.
The
experimental induction of infection was carried out with 2 ml of non-cytopathic pestivirus (BVD virus)
suspension containing 5 log10 TCID50/ml (Experiment I) and 4.5 log10 TCID50/ml (Experiment II).