Physiological responses to low atmospheric pressure stunning and the implications for welfare

DEF McKeegan, DA Sandercock, MA Gerritzen

Research output: Contribution to journalArticleResearchpeer-review

15 Citations (Scopus)

Abstract

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.
Original languageEnglish
Pages (from-to)858 - 868
Number of pages11
JournalPoultry Science
Volume92
Issue number4
Publication statusFirst published - 2013

Fingerprint

atmospheric pressure
physiological response
electroencephalography
electrocardiography
consciousness
birds
heart rate
poultry
unconsciousness
stunning methods
arrhythmia
seizures
distress
posture
hypoxia
anesthesia
slaughter
broiler chickens
oxygen
muscles

Keywords

  • Electroencephalogram
  • Low atmospheric pressure
  • Poultry
  • Stunning
  • Welfare

Cite this

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title = "Physiological responses to low atmospheric pressure stunning and the implications for welfare",
abstract = "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.",
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Physiological responses to low atmospheric pressure stunning and the implications for welfare. / McKeegan, DEF; Sandercock, DA; Gerritzen, MA.

In: Poultry Science, Vol. 92, No. 4, 2013, p. 858 - 868.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Physiological responses to low atmospheric pressure stunning and the implications for welfare

AU - McKeegan, DEF

AU - Sandercock, DA

AU - Gerritzen, MA

PY - 2013

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N2 - 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.

AB - 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.

KW - Electroencephalogram

KW - Low atmospheric pressure

KW - Poultry

KW - Stunning

KW - Welfare

M3 - Article

VL - 92

SP - 858

EP - 868

JO - Poultry Science

JF - Poultry Science

SN - 0032-5791

IS - 4

ER -