Pre-weaning bovine respiratory disease in the cow-calf herd

Abstract

Bovine respiratory disease (BRD) in beef calves prior to weaning is a problem for 1 in 5 cow-calf farms. Preweaning BRD is a costly problem for the cattle industry and a detriment to animal well-being. This is a perplexing health problem because ranch calves typically live in conditions of little stress and relative isolation, risk factors commonly associated with BRD in weaned calves. Some factors that appear to be related to BRD risk in pre-weaned calves are waning maternal immunity, loss of herd immunity in herds with short calving periods, activities that result in increased animal density, calf gender, and age of the dam. Collectively, these factors are related to the calf’s ability to resist infection and to opportunities for pathogen exposure. Activities such as commingling and weaning may have less impact on calf health if they are completed prior to or after calves are 3 to 5 months of age, thereby avoiding the period of greatest susceptibility. Vaccination programs intended to induce adequate immunity in calves prior to 90 days of age have shown some efficacy, but require further study.