Understanding and preventing bovine respiratory disease (BRD) — the leading cause of calf morbidity and mortality.
Bovine respiratory disease causes significant acute welfare impairment in affected calves. Fever, coughing, nasal discharge, laboured breathing, and depression characterise clinical disease. Calves with BRD are in genuine respiratory distress — the effort of breathing is visible, appetite is suppressed, and calves become progressively weaker without treatment. Severe cases develop pleuropneumonia, lung abscesses, and respiratory failure.
The welfare burden of sub-clinical BRD is substantial and often overlooked. Calves with lung damage that does not reach the clinical threshold for intervention suffer ongoing respiratory compromise. Damaged lungs heal slowly with fibrosis — calves with significant subclinical BRD grow more slowly and have permanently reduced respiratory capacity as adult animals.
Prevention is paramount. Adequate colostrum intake in the first hours of life provides passive immunity against respiratory pathogens. Appropriate housing ventilation (without draughts), correct stocking density, vaccination against key respiratory pathogens, and stress minimisation at critical transitions all reduce BRD incidence and welfare impacts.