Broiler Chicken Stunning Methods During Slaughter

Published: February 2, 2023

By: Jaelen Cherry, University of Maryland; Dr. Shawna Weimer, University of Arkansas; Reviewers: Dr. Marisa Erasmus, Purdue University; Dr. Prafulla Regmi, University of Georgia; Dr. Leonie Jacobs, Virginia Tech.

Broiler Chicken Stunning Methods During Slaughter - Image 1

What is Stunning? How is it Regulated?

Stunning is the process of rendering broilers unconscious or insensible before slaughter and various mechanisms may be used in facilities to achieve insensibility (Humane Slaughter Association, 2015). The methods used depend on the facility's location (on-farm vs. in a slaughter plant), the number of broilers slaughtered, and company program-specific criteria and restrictions. The Humane Slaughter Act of 1978 was passed in the United States to protect livestock handling during slaughter. However, it does not address the slaughter of poultry. Instead, the U.S. requires that poultry slaughter establishments follow “good commercial practices”. Further, regulations require that good commercial practices must ensure a thorough bleeding of the poultry carcass and that breathing has stopped before scalding. As a result, stunning is common practice for broiler chicken processing in the U.S. (USDA-FSIS, 2015). This is a different regulatory system than the European Union, which has a specific legislation that requires broilers to be insensible to pain until death occurs (Official Journal of the European Union, 2009).

Why is Stunning Used?

Stunning is used to render birds insensible to the pain caused during the slaughter process. Stunning prevents unnecessary pain and prolonged distress (Bracke et al., 2020) during the processing phase. Not achieving insensibility is a major welfare concern, due to the pain and distress broilers would face during the cutting and bleed-out phases.

What are the Different Stunning Methods?

Why Does Stunning Matter?

The stunning of broilers before slaughter helps ensure that broiler welfare is protected. In addition, stunning renders broilers unconscious to permit enough time for the bleeding phase (i.e., cutting of the ventral arteries) to occur (Bracke et al., 2020). Without stunning, unnecessary pain and distress would be experienced by broilers, leading to animal welfare concerns. Each stunning method has advantages and disadvantages in terms of in terms of economic (labor) and animal welfare considerations (pain, distress, success rate). The chosen method must demonstrate successful stunning while being feasible for the producer.

This article was originally published on Poultry Extension Collaborative (PEC) and it is reproduced here with permission from the authors.

Abeyesinghe, S. M., McKeegan, D. E. F., McLeman, M. A., Lowe, J. C., Demmers, T. G. M., White, R. P., Kranen, R. W., Bemmel, H. van, Lankhaar, J. A. C., & Wathes, C. M. (2007). Controlled atmosphere stunning of broiler chickens. I. Effects on behaviour, physiology and meat quality in a pilot scale system at a processing plant. British Poultry Science, 48(4), 406–423. https://doi.org/10.1080/00071660701543089

Berg, C., & Raj, M. (2015). A Review of Different Stunning Methods for Poultry-Animal Welfare Aspects (Stunning Methods for Poultry). Animals : an open access journal from MDPI, 5(4), 1207–1219. https://doi.org/10.3390/ani5040407

Bracke, M., de Jong, I., Gerritzen, M., Jacobs, L., Nalon, E., Nicol, C., O’Connell, N., & Porta, F. (2020). The Welfare of Broiler Chickens in the EU. https://www.eurogroupforanimals.org/files/eurogroupforanimals/202011/2020_11_19_eurogroup_for_animals_broiler_report.pdf

Electrical Waterbath Stunning of Poultry. (2015). Humane Slaughter Association. https://www.hsa.org.uk/downloads/hsagn7electricalwaterbathpoultry1.pdf

Lambooij, B. & Hindle, V. Electrical stunning of poultry. (2018). Advances in Poultry Welfare. Mench, J. A. editor. pp. 7798.

Mechanical methods—Non-penetrative captive-bolt. (n.d.). Retrieved April 22, 2022, from https://www.hsa.org.uk/mechanical-methods-poultry/non-penetrative-captive-bolt

Official Journal of the European Union (2009) Council Regulation (EC) No. 1099/2009 of 24 Sept. 2009 on the Protection of Animals at the time of killing. pp. 1-30.

Raj, A. B. M., & O’Callaghan, M. (2001). Evaluation of a pneumatically operated captive bolt for stunning/killing broiler chickens. British Poultry Science, 42(3), 295–299. https://doi.org/10.1080/00071660120055232

USDA FSIS. United States Department of Agriculture Food Safety and Inspection Service. (2015). Humane Handling of Livestock and Poultry. https://www.fsis.usda.gov/sites/default/files/media_file/2021-03/humane_handling_booklet.pdf

Vieira, G, & Peacock, J. R. (2021). Prevalence of Stunning Methods in Broiler Chicken Slaughter in the United States. https://doi.org/10.17605/OSF.IO/5NBYS

Webster, A. B., & Fletcher, D. L. (2001). Reactions of laying hens and broilers to different gases used for stunning poultry. Poultry science, 80(9), 1371–1377. https://doi.org/10.1093/ps/80.9.1371

Woolcott, C. R., Torrey, S., Turner, P. V., Serpa, L., Schwean-Lardner, K., & Widowski, T. M. (2018). Evaluation of Two Models of Non-Penetrating Captive Bolt Devices for On-Farm Euthanasia of Turkeys. Animals : An Open Access Journal from MDPI, 8(3), 42. https://doi.org/10.3390/ani8030042