Immune response to bovine respiratory disease vaccine immunogens in calves at entry to feedlot and impact on feedlot performance

Abstract

Predictors of feedlot performance including clinical illness (morbidity), treatments, cost of treatments, and economic return of calves in a retained ownership program were measured using testing of samples collected at entry from post-weaning calves. At the delivery point, cattle were processed and samples were collected for laboratory testing, including nasal swabs for viral and bacterial isolation, EDTA blood for viral isolation from peripheral blood leukocytes, and serums for antibody testing against bovine herpesvirus-1 (BHV-I), bovine viral diarrhea virus (BVDV) 1a and BVDV2a, parainfluenza-3 virus (PI-3V), bovine respiratory syncytial virus (BRSV), Mannheimia haemolytica whole cell (WC) antigen, M. haemolytica leukotoxin (LKT), and Pasteurella multocida outer membrane proteins (OMP). Feedlot performance records and carcass data obtained at the close of the feeding period revealed predictors of feedlot performance and economic return based on lower or higher levels of serum antibodies to several BRD pathogens. These were based on both individual animal comparisons and herd averages. On an individual animal basis, low antibodies to BVDV1a, BVDV2a, M. haemolytica WC, M. haemoytica LKT, P. multocida OMP, BHV-1, PI-3V, and BRSV were associated with one or more of the following: increased morbidity, increased number of treatments, increased treatment costs, and decreased net value to owner (carcass value minus total costs in the feedlot). On a herd basis, low antibodies to BVDVIa, BHV-I, P. multocida OMP, M. haemolytica WC, and M. haemolytica LKT were associated with one or more of the following: increased morbidity, increased number of treatments, increased treatment costs, and decreased net value to owner. These results reaffirm that post-weaning calves with increased immunity to (antibody levels) BVDV, BHV-I, PI-3V, BRSV, M. haemolytica, and P. multocida perform better in the feedlot with less effects clinically to these BRD pathogens and provide greater economic return to the owner. Management for the breeding cow-herd owner retaining calves for feedlot delivery should stress vaccination against these pathogens.