Weaning is one of the most stressful events in a beef or dairy calf's life, causing prolonged vocalisation, reduced feed intake, weight loss, and immunosuppression that increases disease susceptibility.
Weaning stress is both acutely distressing and has lasting consequences — immunosuppression in recently weaned calves increases susceptibility to BRD and other diseases, creating a welfare cascade from a management event. The prolonged vocalisation documented in separated calves reflects active distress rather than simply a social behaviour, and cortisol data confirm significant physiological stress. Management interventions that reduce stress — two-stage weaning, fence-line contact, pre-weaning adaptation — have clear welfare benefits and in many cases economic benefits through reduced disease and better weight gain post-weaning. The question of dairy calf early separation is particularly ethically significant: cows and calves separated within 24 hours show acute distress in both individuals, and alternatives including extended contact systems are feasible in some production contexts.