At the time of slaughter, animals should be healthy and physiologically normal. Slaughter animals should be adequately rested. They should be rested, preferably overnight, particularly if they have travelled for some times over long distances. Animals should be watered during holding and can be fed, if required. The holding period allows for injured and victimised animals to be identified and for sick animals to be quarantined.
When ready for slaughter, animals should be driven to the stunning area in a quiet and orderly manner without undue fuss and noise. Droving can be facilitated using flat canvass straps, rolled plastic or paper, and in the case of stubborn animals, prodders can be used occasionally. Animals should never be beaten nor have their tails twisted. Animals should be led in single file into the stunning area where they can be held in appropriate restraining device(s) before stunning.
It is very important that slaughter animals should be properly restrained before stunning or bleeding. This is to ensure stability of the animal so that the stunning operation can be carried out accurately and properly.
A stunning box is the most common method of restraining cattle. The size of the box should be just wide enough to prevent the animal from turning around, and so be difficult to stun. The floor of the box should be non-slip. A simple neck crush used by farmers to restrain cattle for weighing is suitable for small-scale operations. Restraining tame cattle outside the stunning box by securing the head in a halter and then pulling the rope through a metal ring in a concrete floor is effective. It is recommended that the operator should be positioned behind protective steel bars.
This method produces a physical shock to the brain.
This method works on the principle of a gun and fires a blank cartridge and it propels a short bolt (metal rod) from the barrel. The bolt penetrates the skull bone and produces concussion by damaging the brain or increasing intracranial pressure, causing bruising of the brain. The captive bolt is perhaps the most versatile stunning instrument as it is suitable for use on cattle, pigs, sheep and goats as well as horses and camels, and can be used anywhere in the world. There are several different manufacturers of captive bolt pistols, and after the initial expense, running costs are minimal. Users must ensure sufficient supply of cartridges, which may be different in caliber for stunning guns from the different manufacturers. These features make the captive bolt the stunning instrument of choice, particularly in developing countries.
There are two variations of the gun. One has a handle and trigger. The other comprises hand-held barrel, which is tapped against the skull, which sets of the cartridge explosion.
Another type of bolt has a flat, mushroom end. Unconsciousness is achieved through percussion by strong blow to the skull. The brain is not penetrated, and as the animal is not killed, it is a method that is acceptable in many countries for Halal slaughter. When in use, the captive bolt is positioned on the correct spot on the animal’s head. Poor maintenance is a major cause of poor stunning and the guns must be cleaned and serviced regularly, according to the manufacturer’s instructions.
For effective stunning, it is important that the operator is well trained in its use of the stunning gun. If the operator becomes fatigued, accuracy of stunning is reduced, so in large plants, rotation of two stunners is recommended. Stunning of bigger pigs may require a stronger cartridge, as the sinus cavities of the skull are larger. Large bulls have a bony ridge in the forehead and penetration may be more difficult, requiring off-centre aim.
In circumstances where animals are too fractious to be handled in the normal way, such as when they cannot be loaded on the farm or led into the stunning restraint, gunshot with a free, soft-nosed bullet is effective. A 22-calibre bullet is sufficient for most animals. Shooting with a free bullet can be dangerous to operators. If the animal is to be slaughtered on a farm, it should be accurately shot while standing or lying on soft ground to prevent the bullet from ricocheting.