Boyal, R. S.Buhr, R. J.Harris, C. E.Jacobs, LeonieBourassa, D. V.2022-10-072022-10-072022-090032-5791102000http://hdl.handle.net/10919/112102Efficacious euthanasia by applying man-ual cervical dislocation can be difficult on large and mature poultry. The challenge with using manual cervical dislocation is that the strength required to hold heavy poultry and swiftly apply cervical dislocation can be phys-ically impossible for most people. Therefore, alternative methods of euthanasia are needed for mature and large poultry. Mechanical cervical dislocation using the Koech-ner Euthanizing Device (KED), captive bolt using the Turkey Euthanasia Device (TED), carbon dioxide (CO2), and electrical euthanasia were evaluated for use on 65-wk-old broiler breeders at flock termination. Fol-lowing application of each method, physiological reflexes including the eye nictitating membrane reflex, mouth gaping, and body movement, broken skin, blood loss, kill success, time to cessation of heartbeat, and blood plasma corticosterone levels were assessed. Birds euthanized using the KED had longer response durations for eye nictitating membrane (91 s) and reflexive mouth gaping (161 s) com-pared to TED, CO2, and electrical euthanasia (0-7 s). Body movement durations were also longer for KED (214 s) and TED (209 s) than for CO2 and electrical euthana-sia (0-8 s). The highest percentages of broken skin (93%) and blood loss (96%) were observed for TED, followed by KED (71%, 68%), then CO2 (0%, 6%) and electrical euthanasia (0%, 3%). No significant differences (P = 0.1781) were observed for kill success rates with 98% for KED, 100% for TED, 97% for CO2, and 100% for electri-cal euthanasia at 4-min. Time to heartbeat cessation did not differ between KED (659 s), TED (427 s), or CO2 (583 s) euthanasia methods. No heartbeat was detected following electrical euthanasia. Blood plasma corticoste-rone levels did not differ between preeuthanasia or post -euthanasia from any of the methods applied. Based on these results each euthanasia method is acceptable for use with broiler breeders.application/pdfenCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 Internationalbroiler breedereuthanasiapoultryArticle - Refereedhttps://doi.org/10.1016/j.psj.2022.1020001019359016441525-3171