- Birds rendered unconscious by gradually reducing oxygen tension.
- Research looked into welfare concerns of process.
- Data suggest birds not distressed by LAPS.
A STUDY conducted by researchers in Scotland and the Netherlands strongly suggests that a new form of poultry stunning — low-atmospheric pressure stunning (LAPS) — is likely more humane than alternative approaches to rendering birds unconscious prior to slaughter, according to an announcement from the Poultry Science Assn. (PSA).
The results of the study appeared in an article titled "Physiological Responses to Low Atmospheric Stunning & the Implications for Welfare" in a recent issue of Poultry Science, which is published by PSA.
"Electrical stunning remains the world's most widely used method of rendering poultry unconscious prior to slaughter," according to lead author Dr. Dorothy McKeegan with the Institute of Biodiversity, Animal Health & Comparative Medicine at the University of Glasgow in Scotland.
However, "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," she added.
"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," she explained.
In LAPS, poultry are rendered unconscious just prior to slaughter by gradually reducing oxygen tension in the atmosphere, PSA said.
The researchers noted that since this process raises "legitimate welfare concerns (regarding) the experience of birds before loss of consciousness," the goal of their study was to address these concerns through collecting and analyzing physiological data during the LAPS process to determine whether there were any indicators of distress to the birds.
To determine whether the LAPS process is stressful, the researchers outfitted 28 broiler chickens 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 that currently uses LAPS.
The researchers found that, based on the EEG analysis, a conservative estimate of the time to loss of consciousness during the application of LAPS was 40 seconds. During this period, they noted an increase in slow-wave (delta) brain activity, consistent with a gradual loss of consciousness.
The increase in delta wave activity set on within 10 seconds of beginning LAPS and continued thereafter, peaking at 30 seconds into LAPS, at which point it was consistent with the EEG signals of birds under surgical levels of anesthesia, according to the announcement.
From the EKG analysis, the researchers found that, during the application of LAPS, the birds' heart rates consistently decreased (Figure). They found no instances in which heart rates increased during the period when the birds were potentially conscious. They also observed no behavioral responses that would suggest aversion to the LAPS process.
The researchers 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."
The full open-access article is available at http://ps.fass.org/content/92/4/858.