Animal welfare assessment of on-farm euthanasia methods for individual, heavy turkeys

Authors: LEONIE, JACOBS - Virginia Tech; BOURASSA, DIANNA - Auburn University; BOYAL, RANJIT - Auburn University; Harris, Caitlin; Bartenfeld Josselson, Lydia; CAMPBELL, ANDREW - Virginia Tech; ANDERSON, GRACIE - Virginia Tech; Buhr, Richard - Jeff

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2020
Publication Date: 11/10/2020
Citation: Leonie, J., Bourassa, D.V., Boyal, R.S., Harris, C.E., Bartenfeld Jossel, L.N., Campbell, A., Anderson, G., Buhr, R.J. 2020. Animal welfare assessment of on-farm euthanasia methods for individual, heavy turkeys . Poultry Science. 100:100812. https://doi.org/10.1016/j.psj.2020.11.001.
DOI: https://doi.org/10.1016/j.psj.2020.11.001

Interpretive Summary: On-farm euthanasia is needed when poultry, including broiler chickens and turkeys, are unhealthy, immobile, or otherwise incapacitated. The American Veterinary Medicine Association recently published (2020) recommendations for euthanasia for poultry, including “gas inhalation, manually applied blunt force trauma, cervical dislocation, decapitation, electrocution, gunshot, captive bolt, and injectable agents”. In the current study, mechanical cervical dislocation with the Koechner Euthanizing Device (KED), captive bolt euthanasia with the Turkey Euthanasia Device (TED), head-only CO2 euthanasia (CO2), and electric euthanasia were compared for their impact on loss of brain stem reflexes (insensibility), acute distress (blood serum corticosterone, CORT), kill success, skin damage and blood loss. Turkeys (n=174) were euthanized on 3 sampling days and the birds were restrained using a mobile bird euthanasia apparatus. Brain stem reflexes recorded were the cessation and return of induced nictitating (3rd eye lid) membrane reflex (indicating loss of consciousness and brain stem disfunction), mouth gaping reflex (indicating brain stem disfunction) and musculoskeletal movements (indicating spinal cord disfunction). Loss of consciousness (absence of nictitating membrane reflex) was confirmed at 15 sec after electric euthanasia, 4 min after application of CO2 and TED, but took longer than 3 min for KED euthanasia. Spinal cord death was confirmed at 15 sec post-application for electric and CO2 euthanasia, but took longer than 3 min for KED and TED euthanasia. Returning reflexes were more frequent after KED and TED compared to CO2 and electric euthanasia, where they were absent. CO2, electric, and TED euthanasia showed comparable single application kill success rates, with KED resulting in most unsuccessful kills (8/42) at 4 min after application. CORT responses were inconsistent and did not differ amount methods. Skin damage and blood loss occurred more frequently after KED and TED euthanasia compared no occurrence after CO2 and electric applications. Based on the current study results, the recommended euthanasia method is electric euthanasia, which consistently resulted in quick loss of consciousness (within 15 sec), no returning reflexes, and no external skin damage or blood loss.

Technical Abstract: On-farm euthanasia of poultry, including turkeys, can be strenuous if done manually, thus alternative methods have been developed. In the current study, mechanical cervical dislocation with the Koechner Euthanizing Device (KED), captive bolt euthanasia with the Turkey Euthanasia Device (TED), head-only CO2 euthanasia (CO2), and electric euthanasia were compared for their impact on loss of brain stem reflexes, acute distress (corticosterone, CORT), kill success, skin damage and blood loss. Turkeys (n=174) were euthanized on 3 sampling d. Birds were restrained using a mobile bird euthanasia apparatus. Brain stem reflexes recorded were the cessation and return of induced nictitating membrane reflex (loss of consciousness and brain stem disfunction), mouth gaping reflex (brain stem disfunction) and musculoskeletal movements (spinal cord disfunction). Loss of consciousness (absence of nictitating membrane reflex) was confirmed at 15 sec after electric euthanasia, 4 min application of CO2, and TED but took >3 min for KED euthanasia. Spinal cord death was confirmed at 15 sec post-application for electric and CO2 euthanasia, but took >3 min for KED and TED euthanasia. Returning reflexes were more frequent after KED and TED compared to CO2 and electric euthanasia, where it was absent. CO2, electric, and TED euthanasia showed comparable single application kill success rates, with KED resulting in most unsuccessful kills (n = 8/42). CORT responses were inconsistent over 2 sampling day. Skin damage and blood loss occurred more frequently after KED and TED euthanasia compared no occurrence after CO2 and electric applications. Based on the current results, the recommended euthanasia method is electric euthanasia, which consistently resulted in quick loss of consciousness (within 15 sec), no returning reflexes, and no external skin damage.