Physiological and behavioural changes in Holstein calves during and after dehorning or castration

Physiological and behavioural responses of 17 bull and 12 heifer dairy calves (80.9 ± 1.4 kg) to either hot-iron dehorning or dehorning followed by scalpel castration were compared to both control and sham procedures and to each other. Blood samples were collected via jugular catheters at 15 and 30 min, 1, 2, 4, 24, and 48 h post procedure, sham or control. Cortisol levels remained elevated above controls for at least 2 h after castration and 30 min after dehorning. Initial (T0–T15 min) cortisol responses to castration were not different from those to dehorning. However, they were greater than for dehorning at 2 and 4 h post procedure. Both castrated and dehorned calves kicked and vocalized more frequently (P < 0.05) than during sham procedures. Struggling was greater during dehorning than the sham, but occurred less (P < 0.05) during castration than the sham possibly due to the prior experience of dehorning. Dehorned calves had a higher (P < 0.05) occurrence of both struggling and kicking compared to castrated calves. Heart rate was higher (P < 0.001), compared to control values, in both the sham (P < 0.02) and dehorned calves. Non-anaesthetized dairy calves had elevated cortisol, and heart rate levels as well as more severe behavioural responses to castration and dehorning compared to sham and control treatments. Differences in the responses to each procedure may have been due to handling differences or prior experience of dehorning. Key words: Behaviour, castration, cortisol, dairy calves, dehorning, heart rate