Thursday, 29 August 2013

PROCESSES WHICH ARE INVOLVED IN THE SLAUGHTER OF FARM ANIMAL FOR CONSUMPTION OR OTHER PURPOSES


Preparation of livestock for slaughter

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. However, pigs and poultry are usually slaughtered on arrival as time and distances travelled are relatively short and holding in pens is stressful for them. Animals should be watered during holding and can be fed, if required. The holding period allows for injured and victimized animals to be identified and for sick animals to be quarantined.

Restraint devices

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. Different types of restraints are appropriate for different species:

Cattle

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 this operator should be positioned behind protective steel bar.

Sheep/goats

A properly constructed metal stunning box is appropriate. However, they can be restrained manually quite satisfactorily.

Pigs

A stunning box is suitable for pigs. Putting a few pigs in a small room is suitable but only for electrical stunning. On no account should pigs be restrained manually.

Poultry

Chickens are shackled by their legs onto a conveyor line. This must be done gently to avoid injury and stress. In a small slaughterhouse, birds can be placed headfirst in cones.

Ostriches

These are temperamental animals, and because they will kick, they must be securely restrained. This can be done by leading them into a padded V-shaped pen, with the head facing the apex of the pen. Also the feet can be clamped immediately after electrical stunning has begun.

Animals should never be left standing for a prolonged period in a restraint device and must be stunned immediately after being secured. The operator must be adequately trained and supervised. In some countries, people who handle and stun animals have to be trained and licensed.

Methods of stunning

It is desirable to render an animal unconscious before it is slaughtered in order to eliminate pain, discomfort and stress from the procedure. In some circumstances, traditional slaughter may be exempt from pre-slaughter stunning. Whatever the stunning method, the animal should be rendered unconscious for long enough so that bleeding results in enough loss of blood to cause death from lack of oxygen to the brain. In other words, death should occur before the animal would have regained consciousness after stunning, had bleeding not taken place. There are three main technologies used to effect stunning-Percussion, Electrical and Gas. Only the first two are commonly used in developing countries.

Percussion stunning

Captive bolt
This method works on the principle of a gun and fires a blank cartridge and it propels a short bolt 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.

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. A captive bolt gun is not suitable for stunning ostriches. Their brain is small and lobulated, and the bolt does not produce proper concussion.

Gunshot

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.
Electrical stunning
This method of stunning is well suited for pigs, sheep or goats, poultry and ostriches. Electrical stunning induces electroplectic shock or epileptic state in the brain. This state should last for long enough for bleeding to be carried out so that the animal dies from cerebral anoxia. A low voltage alternating electric current is applied by means of two electrodes, which are placed on either side of the brain using tongs. Since the brain of animals is small, the electrodes should be accurately and firmly placed high up on the sides of the head in sheep, goats, pigs and ostriches.
Ostriches should be stunned only electrically. The tongs are placed either at the sides of the head below and behind the eye or above and below the head. Poultry can be stunned electrically using a manually operated device or using an automatic water bath.


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