The objective of this study was to evaluate the impact of environmental factors on the serological response to commercial bovine viral diarrhea type 2 (BVDV2) vaccinations in Angus cattle for inclusion as fixed effects into subsequent genetic evaluations for response to vaccination.Age of calf was found to have a significant effect on the serum titer level at the time of initial vaccination, with older calves halving a lower titer level. Furthermore, it was observed that animals with a higher serum titer level at the time of vaccination had a reduced increase in titer as a result of a vaccination. We also observed smaller response to vaccination in calves which experienced the stress of weaning at the same time as their initial vaccinations.

Based on this initial study, we have adjusted experimental protocols for subsequent work to collect samples to evaluate individual animal rate of maternal antibody decline and to remove confounding of stress of weaning with calving season effects.