Using Serum Cortisol to Distinguish Between Acute Stress and Pain Response Following Castration in Piglets
and Implications In the United States swine industry, castration is essentially universal and only a select number of male pigs are left intact as potential breeder boars. Pain and distress inflicted by castration is an animal well-being concern in livestock production. To minimize the stress it has been recommended that this procedure should be conducted in the first wk of life. Therefore, the objective of this study was to evaluate plasma cortisol differences between a stressful (manual
... ssful (manual restraint) and painful (castration) event under controlled conditions. One hundred cross-bred male pigs 9 to 11 d of age were chosen at random from 24 litters. Fifty piglets were randomly assigned to be castrated (CAST) with the remainder sham castrated (SHAM). Processing tie was different between pre and post samples (P < 0.0001). Pre treatment blood samples was 38.8 min and post treatments blood samples was 45.5 min respectively. Processing times for SHAM and CAST pre (P = 0.98) and post (P = 0.46) treatment blood samples were not different. Pre-castration values were not different (P > 0.05) between CAST and SHAM groups. The post-castration mean value of cortisol for the SHAM group increased from 73.5 nmol/L to 145.3 nmol/L (P < 0.0001). The CAST group serum cortisol increased from 75.4 nmol/L to 357.3 nmol/L (P < 0.0001). Post-castration values were different (P < 0.0001) between the SHAM (145.3 nmol/L) and CAST group (357.3 nmol/L). This study measured a distinct difference between piglets that experienced stress due to restraint and blood collection and piglets that experienced those stresses plus castration.