Harold Hillman, Mb, BSc, PhD on The
When stunning is not done properly or exsanguination has not progressed enough, a significant proportion of animals is burnt before going unconscious.
Approximately 750,000,000 animals and 650,000 tons of fish are
slaughtered each year for food in Britain. The number of fishes is not known
because they are weighed, and small fishes are thrown back dead into the sea
because it is illegal to land them. Anglers catch an additional number of
fish, and an unknown number of birds and rabbits are shot.
Methods of Slaughter
Farm animals are stunned by electricity or percussion, and killed by cutting the blood vessels in the neck, causing exsanguination. The halal and shechita method, used by Moslems and Jews, involves cutting the neck without stunning the animals. Shooting may be at close quarters, e.g. of horses, or from a distance, e.g. birds and rabbits. Fish caught at sea or by anglers die of asphyxia, when they are taken out of the water; anglers sometimes throw fish back after withdrawing the hooks; the fish may then die of inability to eat, or microbial or fungal infections. Trapping, snaring and hunting are rarely used in Britain for animals which are to be eaten.
Two Kinds of Stunning
Most animals in Britain are stunned. Bailhere's Comprehensive Veterinary Dictionary (1988) defines it as "producing unconsciousness of head in carbon dioxide, gas, electrical shock ... all of them aiming to allow the animal to bleed out while it is still alive. An animal that is dead before it has bled out will be unsuitable for marketing." The latter definition regards stunning as rendering an animal unconscious, and the exsanguination as the cause of death. However, the Oxford English Dictionary (1989) says that the aim of stunning is "to deprive of consciousness or power of motion [my italics] by a blow, a fall or the like." The author of this entry gives paralysis as an alternative to loss of consciousness.
The captive bolt may penetrate the skull and destroy brain tissue, or cause a considerable rise in intracranial pressure. These result in instantaneous loss of consciousness (as a knock-out does in boxing), followed by collapse of the animal. If the brain tissue is not destroyed, the animal may come round, if the carotid arteries and jugular veins are not cut soon ("sticking"). Instant unconsciousness occurs if the aim is accurate, the animal is still, and the device works. Electrical stunning involves passing a large voltage across the animal's brain. Slaughtermen, butchers, the Royal Society for the Prevention of Cruelty to Animals, the People's Dispensary for Sick Animals, Compassion in World Farming and most people who eat meat, assume that the electric current causes instantaneous unconsciousness, so that the animals feel no pain. Unfortunately, there is evidence that this assumption may not be warranted.
Sensory and Motor Nervous Systems
Early in the 19th century, the neurologists Sir Charles Bell in Britain and Francois Magendie in France recognised the distinctions - both anatomical and physiological - between the sensory and motor nervous systems. Electric stimulation of the skin with low voltages and currents causes a tingling sensation, while higher power causes pain and burns, due to action on the sensory nerve endings in the skin. Stimulation of motor nerves or of muscle directly with low voltages and currents, causes muscles to contract, while higher powers causes spasm and paralysis. It is an everyday experience that, for example, a patient whose finger is anaesthetised locally to lance a whitlow, can still flex it. A spastic person can still feel. It is not permitted to do experiments on paralysed animals, because they can still feel. Every physiologist, doctor and nurse, encounters examples showing the distinction between the sensory and motor systems.
Can an Electrically Stunned Animal Feel Pain?
There is evidence from human beings that electrical stimulation is painful. Electrical current is widely used to torture people in South America/ the Middle East and China; cattle prods or electric batons are used. Victims of torture attest that the larger the voltage or current, the more painful it is; they do not go unconscious immediately. The power used to torture people is of the same order as that used to stun animals. Greater energy used in the electric chair kills the victim after some minutes, or spoils the taste of meat. Of course, the voltages and currents experienced by the human beings or animals are much lower than those coming out of the devices they use, because the electrodes can not be applied accurately and firmly, and there are alternative pathways across the skin, through the skin and into the tissues. In the case of prisoners in the electric chair, the electrodes are moistened and bound firmly to the head and foot to ensure good contact.
Burns occur at the sites of contact with the electrodes. Those due to torture of human beings may be very small. They have been detected histologically in biopsies taken from victims at the Rehabilitation and Research Centre for Torture Victims in Copenhagen. Massive burns and charring are seen at the sites where the electrodes are attached when the electric chair is used. Patients who are given electroshock for manic depression, are anaesthetised because of the stress and pain which would be caused. Other patients, whose hearts require defibrillation with large amounts of energy, are now anaesthetised, because those who recovered complained of the pain. Powerful muscle contraction causes painful cramps in athletes. Perhaps the most obvious evidence is that it is painful to touch the electric mains. Why, then, is it so widely believed that electrical stunning is humane?
Why Electrical Stunning is not Believed to be Painful
Firstly, the public, the slaughterers, the farmers and the butchers, have not understood the division of the nervous system into sensory and motor systems. Secondly, animals and people subjected to large currents, being paralysed, can not exhibit the obvious sign of pain - evasive and violent movements. Thirdly, people believe that unconsciousness in animal slaughter (as in the electric chair) is instantaneous. Fourth, N Gregory and S Wotton of the Department of Meat Animal Science of the University of Bristol in 1985 applied the electric current to the heads of sheep for too short a period to stun or kill them; when the current was turned off, the sheep walked away, apparently without distress. They also saw no burns beneath the electrodes. Nevertheless the same research group was of the opinion that "electrical stunning does not cause de-afferentation of the visual cortex in a consistent and prolonged manner." Fifthly, no one wants to know that animals might have suffered severe pain every time they eat a ham sandwich, hold a barbecue or put on their sheepskin liberty bodices.
Large numbers of animals are slaughtered rapidly in an assembly line. Chickens are lifted by their legs when they are fully conscious. Their heads are immersed in water to make electrical contact, but some flutter and are not stunned. Chickens and pigs are subjected to scalding water to remove their feathers and hair. When stunning is not done properly or exsanguination has not progressed enough, a significant proportion of animals is burnt before going unconscious.
Halal and shechita are both widely used in Britain. The animals are not stunned either by percussion or electrical current. Their necks are exposed, and their carotid arteries and jugular veins cut rapidly with a sharp knife; they die by exsanguination. The restraint and sudden exposure of their necks must be stressful, and the neck incision must be painful. Those who practice this method justify it on the grounds that: (a) their religions and holy books have sanctioned it for centuries; (b) cutting with a sharp knife is not painful; (c) the animal becomes unconscious immediately; (d) other methods are also cruel; (e) animals do not suffer pain, or it does not matter.
Slaughter of Fish
The slaughter of fish has received remarkably little attention. Fish die by asphyxia when they are taken out of the water, or when they are ground up in vacuum fishing. If they have been caught in nets, they may be exhausted from the attempts to free themselves. Some customers in Britain prefer the fishes to be sold with their heads still attached. Sometimes fish are gutted while their hearts are still beating, and the beating is prolonged when they are put into ice. There is no reason to believe that fish do not feel pain, and suffer stress in the nets and during their agonal asphyxia.
Few people who eat meat or fish, or products made from them are aware how the animals are killed. Penetrating captive bolts kill the animals most quickly, and percussion is also effective, if they are stuck before they come round. Electric stunning is probably very painful, because the animals are fully conscious when they are electrocuted. It would be impractical to anaesthetise the animals before exsanguinating them, and the procedure of slaughter with carbon dioxide is too slow, although the animals die quite quickly. The challenge to the meat and fish industry is to devise methods of killing animals and fish in more humane ways, but this may not be possible on an industrial scale. It is likely that kinder and less stressful methods would make meat and fish more expensive.
Number of animals killed in the world by the fishing, meat, dairy and egg industries, since you opened this webpage.
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