The article, "Physiological Responses to Low Atmospheric Stunning and the Implications for Welfare" appears in Poultry Science which is published by the Poultry Science Association.
Poultry are rendered unconscious just before slaughter by gradually reducing oxygen in the atmosphere. The researchers found that the LAPS method may be less stressful on birds.
“Electrical stunning remains the world’s most widely used method of rendering poultry unconscious prior to slaughter," said Dr. Dorothy McKeegan of the Institute of Biodiversity, Animal Health and Comparative Medicine at the Univ. of Glasgow. "But concerns about stress caused to poultry by shackling prior to electric stunning and variability in its effectiveness have led to legislation that will reduce the use of this approach in Europe and to the investigation of other approaches that may be less stressful to the bird.
"In our research, we found that LAPS has the potential to improve the welfare of poultry at slaughter by gradually inducing unconsciousness without distress, eliminating the stress of shackling and ensuring that every bird is adequately stunned prior to exsanguination.”
Researchers used 28 broiler chickens outfitted with wireless, self-contained telemetry logging units to capture high-quality, continuous electroencephalogram (EEG) and electrocardiogram (EKG) data. The data recordings were obtained in a commercial poultry processing plant currently using LAPS.
Based on their EEG analysis, researchers found the birds lost consciousness in approximately 40 seconds. They noted an increase in slow-wave (delta) brain activity, consistent with a gradual loss of consciousness. The increase in delta wave activity began within 10 seconds of beginning LAPS and peaked at 30 seconds into the process. At that point delta wave activity was consistent with the EEG signals of birds under surgical levels of anesthesia, the researchers reported.
The EKG analysis showed that during the application of LAPS, the birds’ heart rates consistently decreased. Researchers found no instances in which heart rates increased during the process, and they also observed no behavioral responses that would suggest aversion to the LAPS process.
The authors concluded that “the scientific data strongly suggest that birds do not find LAPS induction distressing,” and that “collectively, the results indicate that LAPS is an effective and humane alternative approach to stunning prior to slaughter.”