Modified-live versus inactivated respiratory viral vaccines for revaccinating beef calves at weaning

Abstract

Objectives: Our objective was to evaluate bovine respiratory disease (BRD) vaccine types [modified-live (MLV) versus inactivated (INA) multivalent respiratory viral vaccines] at weaning on animal performance, morbidity, bovine viral diarrhea virus (BVDV) neutralizing antibody titer responses, and acute-phase proteins (APP) during backgrounding in calves that previously had received a primer MLV vaccination at 2 to 4 mo of age. Materials and Methods: Beef calves that had previously been vaccinated with MLV at 2 to 4 mo of age were transported to the Oklahoma State University Willard Sparks Beef Research Center from 2 herds with known health and vaccination history (block 1, n = 194, initial BW = 233 ± 32.7 kg; block 2, n = 212, BW = 184 ± 43.5 kg) at weaning. Calves were administered either MLV or INA at the receiving facility and again on d 28 after arrival. Arrival BW was used to distribute steer and heifer calves into pens equally; thus, this experiment used a split-plot experimental design with vaccine treatment in the main plot and calf sex in the split plot. Analysis of BVDV serum neutralization panel and APP were based on pen composite samples from 6 representative calves in each pen. Results and Discussion: Antibody titers for BVDV 1a were greater (P < 0.01) for INA than for MLV. In comparison, BVDV 1b antibody titers were greater for INA on d 14 and 28 but did not differ from MLV on d 42 or 56. Dry matter intake was greater (P < 0.01) for MLV than INA from d 28 to 42 following booster vaccination and from d 0 to 56. This resulted in a greater (P < 0.01) ADG from d 0 to 56 for MLV. Gain:feed, morbidity, or APP concentrations did not differ (P ≥ 0.22) between treatments. Implications and Applications: Revaccination with an INA at weaning provided a more robust BVDV vaccination response compared with MLV following a preweaning priming MLV vaccination at 2 to 4 mo of age.