Comparative effects of castration and dehorning in series or concurrent castration and dehorning procedures on stress responses and production in Holstein calves.

The study objective was to compare serum cortisol as an acute stress measure, chute exit velocity as a behavioral measure, and ADG as an indi- cator of performance and well-being after castration, dehorning, or concurrent castration/dehorning of calves when performed in parallel and in series. Intact male Holstein calves, 3 to 4 mo, underwent sham handling before 2 procedures performed in series separated by 2 to 3 wk. In Period 1, calves were either dehorned by amputation, surgically castrated, concurrently castrated/ dehorned, or served as nonsurgical controls (n = 10/ treatment). In Period 2, calves that had been dehorned, castrated, or castrated/dehorned were then castrated, dehorned, or served as nonsurgical controls, respective- ly. Indicators of distress were measured after all proce- dures; ADG was assessed for 7 d after each procedure and over the 2 to 3 wk interim. Period 1 cortisol concen- trations in dehorned calves were less than in castrated and castrated/dehorned calves at 120 min and from 50 to 240 min, respectively (P < 0.02). There was mar- ginal evidence that cortisol concentrations were greater in castrated/dehorned than castrated calves at 60 min (P = 0.06). Period 2 cortisol concentrations were less in dehorned than castrated calves at 120 min (P = 0.005) but were greater from 360 to 480 min (P < 0.002). The Period 2 cortisol profile of control calves did not dif- fer from the baseline obtained during sham handling, despite the intervening castration/dehorning in Period 1, suggesting that memory did not affect cortisol. The cor- tisol profile of castrated calves did not differ between periods except at 720 min, when Period 1 concentrations were greater than Period 2 (P = 0.02). Cortisol concen- trations of calves dehorned in Period 2 were greater than those dehorned in Period 1 at 20 and 240 to 480 min (P < 0.05). In both periods, castrated calves exited the chute slower than dehorned calves (P < 0.05). The ADG did not differ between surgically treated calves in Period 1; in the interim, the ADG of castrated calves was great- er than that of castrated/dehorned calves (difference ± SED, 1.4 ± 0.6 kg/d; P = 0.03), and in Period 2, the ADG of dehorned calves was less than castrated calves (1.8 ± 0.6 kg/d; P = 0.005). Our study supports both the com- mon practice of concurrent castration/dehorning and the sequence of dehorning and castration. Delayed dehorn- ing (vs. delayed castration) appeared to be more acutely stressful and more detrimental to ADG.