The study objective was to examine effect of age at castration on stress indicators and performance of 40 crossbred suckler beef calves. Calves were assigned to two age groups and two castration treatments; calves 2.5-or 5.0-mo-old (mean body weight (SD) = 120.8 (29.3), 218.1 (30.8) kg, respectively) were sham (control) or Burdizzo castrated (n = 10 per treatment) in a 2 × 2 factorial design. Following castration, peak plasma cortisol concentrations were greater in 2.5-mo-old and 5.0-mo-old

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... es compared with corresponding controls, while peak cortisol concentrations in control animals were greater in 5-mo-old compared with 2.5-mo-old calves. The integrated cortisol responses for the first 4 h after castration were not different between 2.5-and 5.0-mo-old calves. However, the integrated cortisol response was greater in 5.0-mo-old calves from 4 to 9 h post treatment. The increase in scrotal circumference after castration was greater in 5.0-mo-old calves, and abnormal postures were observed more often in 5-mo-old castrates. There was no effect of castration on haematology profiles, haptoglobin, metabolites, body temperature and growth performance. In conclusion, the physiological stress, inflammation and pain-related behaviours caused by Burdizzo castration were reduced when castrating calves at 2.5-than at 5.5-mo-old.