Mechanical methods - Non-penetrative captive-bolt

A captive-bolt device powered by a blank cartridge propels a short, mushroom-headed bolt to deliver a fatal percussive blow as described in the mammal section (captive-bolt). Unlike free-bullet firearms, the bolt remains captive within the barrel because the flange and the buffers returns the bolt to the pre-firing position after the shot.  This bolt strikes the animal’s head (percussion) which causes concussion and trauma to the brain. In smaller animals such as poultry this blow is sufficient to produce significant damage to the skull and brain resulting in immediate loss of consciousness and death.

For the application of the captive-bolt device the birds should be restrained in cones, shackles or by hand. The bird’s head should be held lightly by holding the beak, gently between thumb and finger. The muzzle of the captive-bolt should be positioned on the highest point of the head on the midline of the skull. When looking from the side, the captive-bolt should be pointing towards the area between the bird’s eye and ear at 90 degrees to the head. When the bolt is projected allow the head to be propelled out of your hand. Do not try to hold on to the head after firing.

 For a small bird such as a chicken you can use either a flat or convex head. For larger birds (duck, goose, and turkey) we recommend that you use a convex head. See Table 4 below for guidelines and consult the HSA technical poster http://www.hsa.org.uk/shop/publications-1/product/stunning-poultry-mechanical-percussive-devices for further information.

Table 4: Captive-bolt head design and suitability for poultry species.

If there is any doubt regarding the efficacy of the shot an alternative method such as cervical dislocation should be performed immediately. When used for killing for disease control, access to more than one device may be necessary to prevent overheating. A back-up device should always be available. See the HSA online guide to Emergency Killing and Captive-bolt Stunning of Livestock for more detailed information on the use of captive-bolt equipment. Information is available on the types of equipment available, the correct positioning for different species and the maintenance procedures and safety considerations for captive-bolt equipment. For specific advice regarding non-penetrative stunners for use with adult poultry consult the HSA technical poster http://www.hsa.org.uk/shop/publications-1/product/stunning-poultry-mechanical-percussive-devices

Considerations when using non-penetrating captive-bolts during depopulation due to disease control

This method induces an immediate onset of unconsciousness in birds of all ages.  When using non-penetrative captive-bolt devices on-farm, there are some factors to be taken in to consideration.

Care must be taken to ensure the device is well maintained and the positioning is correct when applying the technique. Following the blow, post-stun convulsions can be dangerous to handlers when working with large, heavy birds such as turkey stags; therefore care must be taken to ensure the personnel performing the killing are not injured by involuntary wing flapping. It may not be feasible to use this method for disease control on large farms, particularly with caged poultry as they have to be handled and restrained individually. In these situations alternative methods, such as those described in the following sections may be more suitable.

Conclusion – species and situations

When using cartridge powered devices this method is suitable for killing relatively small numbers of adult poultry on-farm. However, when using compressed-air-powered captive-bolt equipment, larger numbers of birds may be killed in a relatively short time. Care must be taken to ensure the blow delivered by the captive-bolt device is sufficiently powerful and the correct bolt head is used for the species involved.

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