Field comparison of intranasal and injectable bovine respiratory disease vaccination on beef calf antibody concentrations, average daily gain, and bovine respiratory disease morbidity

Bovine respiratory disease (BRD) is a multifactorial disease complex that is common in feedlot operations, where it causes major economic loss through: reduction in average daily gain, treatment costs, and mortality. Reducing BRD incidence would increase profits to producers, reduce antimicrobial use, and improve animal welfare. Two studies were performed to compare clinical vaccine response. First, a randomized control study enrolled 75 crossbred heifer calves into an injectable modified live viral (IJ-MLV) group, intranasal homologous boost (IN-MLV) group, or intranasal heterologous boost (IN-KV) group. Vaccines were administered at birth, ‘‘turnout’’ (~2 months of age), and weaning. Blood samples and weights were collected at ‘turnout’, two weeks post ‘turnout’, weaning, and two weeks post weaning, with weights also being collected at birth and 87 days post weaning. Blood samples were analyzed with an ELISA for bovine respiratory syncytial virus (BRSV) and bovine herpes virus type 1 and virus neutralization for bovine viral diarrhea virus types 1 and 2. No differences were observed between the average daily gains of the three groups. The IN-KV group had significantly higher BRSV antibody concentrations than the other groups at all time points except for ‘turnout’ but had lower bovine viral diarrhea virus type 2 concentrations at weaning and two weeks post weaning. Next, a field study was conducted at two commercial ranches in central Saskatchewan, enrolling 645 calves from one farm and 481 calves from a second farm. The calves were randomly enrolled by vaccine type at branding into either an IJ-MLV group or IN-MLV group. Calves were managed extensively, until weaning when they were moved to a local feedlot. At the feedlot calves were vaccinated and separated into steer and heifer pens and were monitored daily for disease. Weights were collected upon arrival and at 60 days post weaning. Morbidity and mortality due to bovine respiratory disease and average daily gains were analyzed. The results show no significant difference between the two groups for these outcomes. These two studies show the importance of considering vaccine type and administration route when developing BRD control programs