Effects of ambient temperature and water vapor on chamber pressure and oxygen level during low atmospheric pressure stunning of poultry

Poultry Science
Paul H Holloway, David G Pritchard

Abstract

The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure. Ambient temperature affects air density and water vapor pressure and thereby oxygen levels and the time at the minimum total pressure of ∼160 Torr (∼21 kPa) is varied from ∼120 to ∼220 sec to ensure an effective stun within the 280 seconds of each cycle. The reduction in total pressure results in a gradual reduction of oxygen partial pressure that was measured by a solid-state electrochemical oxygen sensor. The reduced oxygen pressure leads to hypoxia, which is recognized as a humane method of stunning poultry. The system maintains an oxygen concentration of <5% for at least 2 minutes, which ensures that birds are irreversibly stunned. Calculated pump down (pressure versus time) data match experimental data very clo...Continue Reading

References

May 15, 2003·American Journal of Preventive Medicine·Cynthia B MorrowLloyd F Novick
Jan 8, 2014·BioMed Research International·Yoshinori Oie, Kohji Nishida
Jun 19, 2014·Journal of the American Veterinary Medical Association·Cia L Johnson
Apr 28, 2016·Physiology & Behavior·Jessica E MartinDorothy E F McKeegan

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Citations

Jul 7, 2020·EFSA Journal·UNKNOWN EFSA Panel on Animal Health and Welfare (AHAW)Virginie Michel
Jul 7, 2020·EFSA Journal·UNKNOWN EFSA Panel on Animal Health and Welfare (AHAW)Virginie Michel
Jun 27, 2019·Animal : an International Journal of Animal Bioscience·J E MartinD G Pritchard

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