Physiological responses to low atmospheric pressure stunning (LAPS) and their implications for welfare

McKeegan, D.E.F. , Sandercock, D.A. and Gerritzen, M.A. (2013) Physiological responses to low atmospheric pressure stunning (LAPS) and their implications for welfare. Poultry Science, 92(4), pp. 858-868. (doi: 10.3382/ps.2012-02749)

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In low atmospheric pressure stunning (LAPS), poultry are rendered unconscious before slaughter by gradually reducing oxygen tension in the atmosphere to achieve a progressive anoxia. The effects of LAPS are not instantaneous, so there are legitimate welfare concerns around the experience of birds before loss of consciousness. Using self-contained telemetry logging units, high-quality continuous electroencephalogram (EEG) and electrocardiogram (EKG) recordings were obtained from 28 broiler chickens during exposure to LAPS in a commercial poultry processing plant. Application of LAPS was associated with changes in the EEG pattern in the form of increases in total power, decreases in mean frequency, and in particular, increases in slow-wave (delta) activity, indicating a gradual loss of consciousness. Increased delta wave activity was seen within 10 s of LAPS onset and consistently thereafter, peaking at 30 s into LAPS at which point the EEG signal shared characteristics with that of birds in a surgical plane of anesthesia. During LAPS, heart rate consistently decreased, with more pronounced bradycardia and arrhythmia observed after 30 s. No heart rate increases were observed in the period when the birds were potentially conscious. After an initial quiescent period, brief body movements (presumed to be ataxia/loss of posture) were seen on average at 39 s into the LAPS process. Later (after 120 s on average), artifacts related to clonic (wing flapping) and tonic (muscle spasms) convulsions were observed in the EKG recordings. Based on EEG analysis and body movement responses, a conservative estimate of time to loss of consciousness is approximately 40 s. The lack of behavioral responses indicating aversion or escape and absence of heart rate elevation in the conscious period strongly suggest that birds do not find LAPS induction distressing. Collectively, the results suggest that LAPS is a humane approach that has the potential to improve the welfare of poultry at slaughter by gradually inducing unconsciousness without distress, eliminating live shackling and ensuring every bird is adequately stunned before exansguination.

Item Type:Articles
Glasgow Author(s) Enlighten ID:McKeegan, Dr Dorothy and Sandercock, Dr Dale
Authors: McKeegan, D.E.F., Sandercock, D.A., and Gerritzen, M.A.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Poultry Science
Publisher:Poultry Science Association
ISSN (Online):1525-3171
Copyright Holders:Copyright © 2013 The Authors
First Published:First published in Poultry Science 92(4):858-868
Publisher Policy:Reproduced under a Creative Commons License

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