Results


PWB020

2007 - 2009

Evaluation of alternative methods of euthanasia for cull turkeys

Principal Investigator: Tina Widowski, University of Guelph
Status: Completed

Background

Over 20 million turkeys are produced annually in Canada. As with other types of animal production, it is sometimes necessary to follow culling or depopulation protocols that are designed to reduce animal suffering. The turkey’s large size makes some methods that are routine in smaller species difficult to perform effectively. In Canada, recommended euthanasia methods for turkeys on farms, as outlined in the current Codes of Practice for Care and Handling of Farm Animals, include blunt force trauma and manual or mechanical cervical dislocation. The American Veterinary Medical Association considers manual cervical dislocation to be an acceptable method for small birds, and the Canadian Council on Animal Care considers mechanical cervical dislocation to be an acceptable method for large birds. Until now, no scientific studies have been conducted to determine which method is the most effective for rapidly rendering turkeys insensible. “Insensibility” is the point at which an animal can no longer feel pain. It can be measured by looking at the nictitating membrane reflex (this membrane is the clear “third eyelid” birds use to moisten or otherwise protect the eye while maintaining vision) and pupil constriction. Rapidly rendering an animal insensible is critical to any euthanasia protocol.

Research Progress

Dr. Tina Widowski and graduate student Marisa Erasmus at the University of Guelph looked at the effectiveness of a device known as a Zephyr Stun Gun for euthanizing turkeys. This air-powered device has been used successfully to euthanize pigs by driving a non-penetrating captive bolt that impacts its target. The researchers compared the Zephyr to other physical methods in terms of time to insensibility and the degree of resulting brain lesions. Small pilot trials were first performed on carcasses to determine appropriate pressure settings for and placement of the device to make it most effective. Based on the results of these trials, the Zephyr was modified such that is could inflict sufficient brain trauma on large (over 10 kg) turkeys. Using the methods and settings developed during the pilot studies, a number of trials were performed using the modified Zephyr on live birds (that were destined for culling) on commercial farms. The researchers looked at time to insensibility and time to death of different weight birds and compared the Zephyr to other euthanasia methods (manual cervical dislocation, mechanical cervical dislocation and blunt force trauma). Brain damage was assessed using macro and micro observation, histology, and CT scans. In the first trial, mature breeder hens (11 kg) were euthanized using the Zephyr or by mechanical cervical dislocation. In the second trial, toms ranging from 17-19 kg from two farms were euthanized by Zephyr or blunt force. In the third trial, broilers were euthanized by Zephyr (4.6 kg), manual cervical dislocation (1.6 kg) or blunt force (5 kg). Results from all trials indicate that the Zephyr is as effective as blunt force trauma at quickly rendering turkeys insensible. Time to insensibility and time to death were both longer using cervical dislocation (manual or mechanical). This study concludes that the Zephyr is a highly repeatable and effective method for euthanasia of birds in all of the weight classes tested. The results also suggest that the methods used for cervical dislocation in large birds, particularly by mechanical means, do not render birds unconscious immediately. Any recommendations for their use need to be reconsidered. Dr. Widowski’s team is planning work to improve the practicality of the Zephyr for on-farm use and will be looking into avenues by which to make the device commercially available to producers.

Funding

$75,579 (CPRC $25,193, NSERC/AAFC $50,386)

Publications

Erasmus MA, Lawlis P, Duncan IJ, Widowski TM. 2010. 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. Poult Sci. 89:1345-54.

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