Frequency of serum antibodies against infectious bovine rhinotracheitis virus and bovine viral diarrhea virus in bulls, and their relationship with the presence of the viruses in semen

The objective was to estimate the frequency of serum antibodies against infectious bovine rhinotracheitis virus (IBRV) and bovine viral diarrhea virus (BVDV) in unvaccinated bulls, as well as the relationship between the presence of antibodies in serum and the presence of these viruses in semen. Antibodies were detected by ELISA, while the presence of viruses in semen was detected by PCR. Logistic regression analyses were performed with PROC GENMOD of SAS. The factors were: status, herd nested in status, and genotype of the bull (except for the presence of viruses in semen). The degree of association between the presence of serum antibodies and the presence of viruses in semen was measured by phi correlation (r). None of the three factors was significant (P > 0.05). For IBRV, the serum antibody frequency by state ranged from 66% to 86%, while by herd it ranged from 28% to 90%. For BVDV, the serum antibody frequency by state ranged from 58% to 76%, while by herd it ranged from 43 to 86 %. The presence of VRIB in semen, by state, ranged from 50 to 55 %, while by herd it ranged from 33% to 80%. No association (P > 0.05) was found between the presence of serum antibodies and the presence of IBRV (r = 0.07) and BVDV in semen (r = 0.16). The presence of serum antibodies suggests infection of the bulls, but the presence of the viruses in semen suggests transmission by sexual contact.