Remove oxygen, kill chickens (Image: Randolph Cheek/TechnoCatch)

LIFE is miserable for the estimated 20 billion broiler chickens raised for food each year – but a new way of knocking the birds out before they are killed may at least give them a more humane death.

Called low atmospheric pressure stunning (LAPS), the system mimics what happens when you climb to high altitudes. Over 5 minutes, air is gradually withdrawn from a chamber until the air pressure is only 20 per cent what it is outside. With less oxygen available, the birds irreversibly lose consciousness. This means they are unable to feel pain when their throats are cut, the standard method employed to kill them.

The technology’s developers, Techno Catch of Kosciusko, Mississippi, claim that LAPS is not stressful for the birds. Now independent research backs up the claim.


It is well known that broiler chickens are housed in cramped and unsanitary conditions, but they also endure a distressing time in the run up to death. They are starved for up to 10 hours to reduce the faecal volume in their bodies, then caught, hung upside down and dunked in an electric bath to knock them out before their throats are slit.

Alternatively, the birds are gassed with carbon dioxide and nitrogen before they are killed, but this can leave them gasping and hyperventilating.

LAPS could provide a more humane alternative. It has been given the “no objection” go-ahead by the US Food and Drug Administration, and is currently being used by OK Foods of Fort Smith, Arkansas. Techno Catch now hopes for similar approval from the European Food Safety Authority by the end of the year.

That hope has been bolstered by two studies from Dorothy McKeegan of the University of Glasgow, UK, which were discussed at a workshop in London last month.

In one, McKeegan monitored the stress levels of birds undergoing the process in a small chamber in her lab. In the other, she looked at birds that went through the commercial chamber at OK Foods (Poultry Science, doi.org/pvn). In both, the birds lost consciousness without any physiological signs of stress.

Electrocardiogram results showed that the birds’ heart rates didn’t rise, instead falling around 40 seconds into the 5-minute cycle when they fell unconscious. Brain activity suggested that the birds drifted through a sleep-like state to brain death.

“[The method] appears to provide good animal welfare outcomes for the birds compared to electrical stunning,” says Craig Johnson of Massey University in Palmerston North, New Zealand, who has studied the humane-ness of religious slaughter methods.

The advantages include less need to handle the chickens and increased reliability compared to electrical methods, says Johnson. It is also said to be cheaper and more hygienic as the birds don’t defecate on themselves. This also means they don’t need to be starved for as long prior to death.

Stunning chickens using this method appears to be better for welfare than electrical methods

Techno Catch says in principle the method could be applied to other livestock and lab animals.

This article appeared in print under the headline “Humane method of chicken slaughter?”