Development of a novel clinical scoring system for bovine respiratory disease (BRD) in weaned dairy calves

Abstract

Bovine respiratory disease (BRD) continues to impact the welfare of dairy calves and the economics of dairy production. As a common cause of morbidity and mortality among dairy calves, BRD was responsible for 46.5% of deaths after weaning and was observed in 11.2% of weaned animals on heifer-raising operations. Costs involved with the disease reach beyond the treatment of clinically ill animals and include reduced growth, reduced milk production, impaired fertility, and premature culling in the first lactation. The prompt and correct diagnosis of BRD is challenging on farms, especially in weaned dairy calves. Weaned dairy calves are typically housed in larger group pens where there is often a lack of restraint and where it is more difficult to monitor them closely. As a result of challenges in correctly diagnosing BRD, cases often become neglected until they are more severe. Several clinical scoring systems to detect BRD in calves have been published. However, available BRD scoring systems for weaned dairy calves are mostly based on data from calves experimentally infected with specific pathogens. The objective of the present study was to develop and validate a scoring system for weaned dairy calves housed in group pens in an on-farm setting that minimizes calf handling.