At the abattoir, meat chickens are stunned (rendered unconscious) before slaughter. This occurs either by electrical waterbath stunning or controlled atmosphere (gas) stunning. Once unconscious, the bird’s throat is cut and bled out to cause death, prior to the bird regaining consciousness.
Electrical stunning is one of the main methods of stunning (rendering birds unconscious before slaughter) used in Australia. It involves birds being shackled upside down and lowered through an electrical waterbath. The aim is that birds immediately lose consciousness on contact with the electrified water.
Unfortunately, there are risks associated with electrical waterbath stunning. How effectively a bird is stunned depends on the electrical frequency of the waterbath, the correct equipment settings, and the electrical resistance of each individual bird.
If the correct frequency is not applied, or the correct procedures, equipment and settings are not used, it can lead to ineffective stunning or even electro-immobilisation while birds are still conscious. Both of these scenarios can result in birds having their throats cut while conscious. If birds are not effectively stunned and also miss the cutting blade, there is a risk they could enter the scalding tank while still conscious.
Handling and shackling can also cause stress to the birds as this occurs while they are still conscious. The shackles can also cause leg pain, and in some cases flapping and struggling while shackling can result in injuries to wings, and possible accidental electric shocks.
What are the alternatives?
There are some aspects of electrical waterbath stunning that can be improved in the short term, including system design and settings, gentle handling methods, and catering more effectively to birds of different sizes or those with visible injuries.
Unfortunately, many of the welfare risks above are inherent to electrical waterbath stunning systems, so research has focused on alternatives with more consistent outcomes. Controlled atmosphere stunning (CAS) and low atmospheric pressure stunning (LAPS) are two alternatives to electric waterbath stunning. CAS uses gases to stun the birds, and this system is widely used in Australia. LAPS is a newer form of stunning where birds are placed in a chamber and the atmospheric pressure is gradually reduced, causing birds to lose consciousness gradually and painfully and is not yet in use in Australia.
Both CAS and LAPS have the benefit of not needing to handle and shackle live birds, reduce stress, and allow greater uniformity of the stun between birds.