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 language | English |
---|---|
Pages (from-to) | 858 - 868 |
Number of pages | 11 |
Journal | Poultry Science |
Volume | 92 |
Issue number | 4 |
DOIs | |
Publication status | Print publication - Apr 2013 |
Keywords
- Electroencephalogram
- Low atmospheric pressure
- Poultry
- Stunning
- Welfare