The Effects of Respiratory Vaccine Type and Timing on Antibody Titers, Immunoglobulins, and Growth Performance in Pre- and Post-Weaned Beef Calves

SIMPLE SUMMARY: Different bovine respiratory vaccine antigen types and timing schedules were utilized to determine the impact on antibody titers, immunoglobulins, and performance in beef cattle. These results suggest that vaccinating calves with a killed viral (KV) vaccine at 2 to 3 months of age and not re-vaccinating per manufacturer specifications did not provide an immune titer response and thus may not provide the preweaning disease protection desired. Vaccination with a modified live (MLV) vaccine appeared to produce a more robust antibody response, even in the face of maternal interference and when given as a booster to animals who previously received a KV vaccination. Delay of initial vaccination (MLV) until weaning may have delayed antibody production and resulted in a lower Th-2 (antibody-mediated) immune response. ABSTRACT: In order to examine the effects of vaccine type and timing of crossbred beef calves (n = 151) were assigned to one of three BRD vaccination protocols stratified by breed of sire, sex, and date of birth, which included: (1) KM—a pentavalent killed viral (KV) vaccine at 2 to 3 months of age (D 0) and a pentavalent modified-live viral (MLV) vaccine at weaning (D 127); (2) MM—MLV on D 0 and revaccinated on D 127 or (3) WN—MLV at weaning and D 140. Vaccination treatment did not affect performance nor BRSV serum-neutralizing antibody titers. Serum-neutralizing antibody titers to BVDV-1 were greatest for the MM through D 154. However, following booster (KM) or initial vaccination (WN) at D 127, titers increased for the other treatment groups to higher values (KM) by the end of the study. Delay of initial vaccination until weaning may have delayed specific antibody response in the WN group and skewed the immune response towards a Th-1 or cell-mediated response. Overall, the inclusion of an MLV in the vaccine protocol resulted in a more robust antibody response, and the timing of vaccination may affect the onset of efficacious and robust vaccine responses.