Using time to insensibility and estimated time of death to evaluate a nonpenetrating captive bolt, cervical dislocation, and blunt trauma for on-farm killing of turkeys

Abstract

The effectiveness of a pneumatic nonpenetrating captive bolt (Zephyr) was assessed for on-farm euthanasia of turkeys and compared with blunt force trauma, manual cervical dislocation, and mechanical cervical dislocation using a burdizzo. The Zephyr (n = 46) and burdizzo (n = 26) were evaluated in turkey hens (11.4 +/- 0.1 kg), the Zephyr (n = 46) and blunt trauma (n = 32) were evaluated in turkey toms (13.1 +/- 0.2 kg), and the Zephyr (n = 12), blunt trauma (n = 11), and manual cervical dislocation (n = 7) were evaluated in broiler turkeys (4.1 +/- 0.3 kg). The nictitating membrane and pupillary light reflexes were monitored continuously to determine when insensibility occurred. Time of death was estimated based on the end time of convulsions and sustained absence of breathing. The nictitating membrane reflex was present immediately after treatment in all 26 hens killed with a burdizzo versus 8 of 46 hens killed with the Zephyr (P < 0.001). The presence of eye reflexes did not differ between the Zephyr and blunt trauma for toms (1 of 26 toms killed with blunt trauma, 2 of 44 toms killed with the Zephyr, P = 1.0). The nictitating membrane reflex persisted in a greater proportion of broiler turkeys killed with cervical dislocation (7 of 7) versus the Zephyr (0 of 12, P < 0.001) and blunt trauma (2 of 9, P = 0.003) but did not differ between blunt trauma and the Zephyr (P = 0.2). End time of convulsions did not differ between the Zephyr and burdizzo for hens (204 +/- 8 vs. 114 +/- 10 s, P = 0.5) or between the Zephyr and blunt trauma for toms (200 +/- 7 s vs. 218 +/- 11.8 s, P = 0.4) but was shorter after cervical dislocation in broiler turkeys (cervical dislocation: 138 +/- 13 s, Zephyr: 165 +/- 7 s, blunt trauma: 178 +/- 13 s, P < 0.001). Results demonstrated that the Zephyr (discharged twice in immediate succession) and blunt trauma (single hit) were similarly effective at consistently causing immediate insensibility. Conversely, neither method of cervical dislocation caused immediate insensibility. This study may assist in revising current poultry euthanasia recommendations.