Methods for Individual Restraint

Static restrainers

Static restrainers are normally used for larger animals such as adult cattle. In order to encourage animals to walk into the restrainer, it should be well lit and the end wall should not be solid so that the animal does not perceive a dead end.

Static restrainer

Restrainer conveyors

Restrainer conveyors are designed for high-throughput abattoirs, particularly for sheep and pigs. They can present animals for head-only, head-to-back or head-to-body stunning. There are two common designs for restrainer-conveyors: either two belts mounted in a V formation which grip animals from both sides and carry them to the point of stunning; or a narrow, single conveyor to support the belly of the animal.

Restrainer conveyor - 'v' formation

Restrainer conveyor - belly rail (courtesy of Temple Grandin)

Animals must be restricted to single file before entering restrainer-conveyors. The handler must be able to reach the entrance of the conveyor from the side in order to encourage animals into it without having to lean over animals waiting to enter, or having to push animals from behind. The speed of the restrainer is also important: it should be slow enough to allow accurate stunning, but fast enough to prevent animals being held for long periods of time.

Stun boxes and crushes

Stun boxes and crushes are used for larger animals, such as cattle, and often incorporate a device to restrict head movement. This could either be an active device, which physically holds the head in position, or a passive device which simply encourages the animal to place its head in the correct position.

Studies have been conducted to assess the impact of head restraint systems in abattoirs on stun accuracy and animal welfare. Although active restraint increases the accuracy of stunning, this advantage does not outweigh the disadvantage of increased stress levels. Passive restraint systems, however, have been found to produce an increase in the accuracy of stunning with no increase in stress levels or the length of time animals spend restrained prior to stunning. 

Active restraint of an animal’s head is a stressful experience and should only be used if absolutely necessary. When active restraint is used, animals should be restrained for as short a time as possible.

The ‘head-yoke and chin-lift’ is an active restraint device that works in two stages: the yoke closes around the animal’s neck and the chin-lift rises to push the animal’s head upwards, resulting in complete immobilisation of the head. Another active restraint design, the ‘cantilever neck-yoke’, has two arms which lie flat against the side of the wall or crush and which move outwards and upwards to close around the neck, preventing the animal from moving backwards and restricting head movement to up and down.

A version of the ‘cantilever neck-yoke’ with one static arm and one moving arm, causes less stress to the animal and is considered a part-passive device. 

Passive devices, such as the 'fixed shelf' do not physically restrain the head, but encourage the animal to place its head in the correct position. 

An ideal head restraint design would consistently position the animal’s head to allow accurate stunning, without compromising animal welfare. To enable this, the design should:

• Not increase the time spent in the stun box
• Be constructed so that the animal enters freely, without hesitation
• Be suitable for the stunning equipment and procedures
• Passively position the head, rather than physically restrain the head
• Not impair the removal of animals from the stun box
• Allow unhindered access for both stunning and re-stunning if necessary
• Release the head immediately after stunning

Next: Specific Requirements for Head Restraint