Most people in Britain are happily unaware of the precise routes by which meat arrives at their table, and even those who know may squeamishly choose to try to forget. Far more comforting to think of a free-range chicken scratching for corn in a farmyard rather than a brittle-boned broiler fowl strung up by its legs to await the slaughterman's knife.
On the factory farm life is cheap and the demand for fast food, intensively produced for the mass market, constantly runs the risk of economies imposed at the expense of the animals' welfare.
It is ironic that if a pet bird was kept in a cage in which it could not spread its wings, the owner could be prosecuted. Yet owners of battery hens and broiler chickens are exempt.
"What are we to make of a law which discriminates against poultry?" asks Dr Ruth Harrison, a founder member of the Farm Animal Welfare Council (FAWC), an independent body which advises the Ministry of Agriculture.
Next time you go to work on an egg, consider the facts. There are 38 million egg-laying chickens in Britain and 96 per cent of them are kept in battery cages.
To be a battery hen is to live in a machine and produce eggs. When you stop laying, you stop living. Your cage measures 18 x 20 inches. According to government recommendations each hen must have a minimum space of 450 sq cm (less than a sheet of A4 paper). This means that each cage may contain four or more chickens. It also means that the occupants are crammed in so tightly they are unable to stretch their wings or pursue natural activities such as perching, foraging and dust-bathing.
A battery chicken never goes hungry even if, as the Edwina Currie saga revealed, it is sometimes fed on the ground-up remains of other chickens. All its life it is kept warm and dry until its last egg is laid and it becomes a "spent" hen. By that time its bones will have become so brittle that one in three battery hens suffers broken legs, wings, even breast bones.
The same condition - osteoporosis - also afflicts broiler chickens, which grow so fast that their legs are unable to bear the overload of meat. Down on the factory farm the broiler business is as intensive as you can get. In Britain there are some 400 million broilers, kept in sheds which hold 20,000 birds or more at a time.
Unlike battery hens, broilers are penned, not caged. As day-old chicks they have plenty of room to move around, but not for long. Their rate of growth is phenomenal. A broiler bird is probably the fastest-growing creature on earth; from hatch to despatch in under seven weeks. That is all it takes to reach a deadweight of 2kg - by which time the birds have expanded to fill all available space, creating conditions as cramped as their egg-laying battery cousins.
One of the most stressful moments in their unnaturally short lives comes when the catching gangs move among them, grabbing them by the legs to pack them off to the slaughterhouse. Injuries are common, and there is now a machine which can do the job more humanely - a kind of combine harvester which can be driven through the broiler house, scooping up birds with its rubber paddles. Unfortunately it is still too expensive to be widely adopted on factory farms.
The cattleman's equivalent of the broiler trade is the baby beef business in which veal calves are confined in individual crates and fed a crash diet of high-energy powdered milk substitutes. The calves grow fast. In their first few weeks they are capable of putting on as much as 1kg per day and, after three weeks, they can no longer turn round.
The exclusive milk diet (no hay or fodder of any kind is allowed) also produces the distinctive tender white meat so admired on the Continent, where the Dutch have pioneered this particular refinement of factory farming - hence the so-called "Dutch crates" measuring 5ft x 2ft, in which the calves are kept.
Some calves are also tethered to prevent them from licking the floor or the sides of their crates, and so they remain, unable to suckle or ruminate, or to lick themselves or groom each other. After 12 weeks they are ready for slaughter, but by this time lack of exercise has taken its toll, and many are too weak to stand when released from their crates for the journey to the slaughterhouse.
In 1986 the agriculture minister responded to widespread concern voiced by the animal welfare lobby and announced that veal calf crates would be abolished in 1989. However, most of the veal sold in Britain is imported from Holland, where the system still flourishes, and the animal welfare lobby would like to see all such meat clearly labelled so consumers can choose whether to eat it or not.
Pigs, too, have to endure similar close confinement in indoor systems such as dry sow stalls. These usually consist of rows of individual tubular steel pens in which sows are held for their 15-week pregnancy. Animals kept in these conditions are unable to turn round, can lie down only with difficulty, and have no physical contact with other pigs. They sleep on concrete floors which may or may not be bedded with straw. Slatting at the rear allows dung to drop through into a pit beneath. In some systems the sows are kept tethered to the floor by chains.
Once the sow has given birth, she is placed in a steel farrowing crate which prevents her from crushing her piglet profits. When the piglets are three weeks old they are removed and put in pens, in mixed litters, to be reared on until at around 14 weeks they weigh 45kg and are ready to become pork or bacon.
The sows, meanwhile, after a few days of relative freedom, are mated again and returned to their stalls. Each sow produces an average of 2.5 litters a year until, at the age of five, she is "spent" and ends her days as pork pie.
The trouble with pigs is that they are intelligent animals, and animals which are more aware will suffer more in an intensive system. "Pigs are very good at learning," says Donald Broom, professor of animal welfare at Cambridge Veterinary School. "Possibly they are even cleverer than dogs and cats." Shut up in a stall, a clever pig soon becomes a bored pig. Unable to carry out its normal activities, it is reduced to repetitive and abnormal behaviour such as bar-biting and sham chewing - typical signs of a pig under stress in a dry sow stall. The current Welfare Code for pigs, published by the Agriculture Department in 1983, admits that keeping sows in stalls with or without tethers raises "serious welfare problems", and the FAWC would like to see them phased out as quickly as is practicable.
"My own opinion is that it is morally obscene to keep a pregnant animal in such conditions," says John Douglas, head of the farm animal department at the Royal Society for the Protection of Animals. "Pigs are very bright animals. They like to know what is going on."
It was Ruth Harrison's book "Animal Machines", written in 1964, that led directly to the setting up of the Brambell Committee. This investigation into the welfare of animals kept under intensive livestock husbandry systems endorsed Ruth Harrison's concerns.
Here, for the first time, was a government committee laying down where the line should be drawn on the use of farm animals. An animal, declared the Brambell Report in 1965, should at least have sufficient freedom of movement to be able without difficulty to turn round, groom itself, get up, lie down and stretch its limbs. These were the basic "Five Freedoms" the Brambell Committee believed all farm animals should be permitted. "Yet today, 24 years later," says Ruth Harrison, "they still haven't got them."
The controversy unleashed by "Animal Machines" also led to the creation of the Farm Animal Welfare Council, which proposes regulations on every aspect of animal welfare from birth to slaughter-house. Since it was set up in 1979 it has produced three reports on animal slaughter and is currently looking at the problems of animal transportation.
It also draws up codes of practice, most of them accepted by the government, but the battery hen system remains a notable exception which still greatly concerns the welfare lobby. The FAWC echoed Professor Brambell's view that even a battery hen should at least have enough room to turn round, groom itself, get up, lie down and stretch its wings. "Clearly the battery system did not meet those minimal criteria," says Ruth Harrison.
The result was a great deal of prevarication on the part of the agriculture ministry so that the legal requirements for battery hens proposed by the FAWC have never been implemented.
"How can we even argue whether an animal should be allowed to turn round and groom itself?" asks Harrison. "Surely it is a self-evident truth?" A Nobel prize-winner once said to her that he wouldn't keep a sloth in such conditions. And there was evidence to suggest that most people, farmers and consumers alike, were in favour of the FAWC recommendations.
In 1968 two polls were conducted by Gallup. One of the questions was: should birds have enough room to spread their wings? The response showed that 78 per cent of the farmers and 91 per cent of the public believed that they should.
Alternatives exist which are both humane and commercially viable, but getting out of battery production is not easy. It is taking the Swiss - who have decided that every hen must have access to a perch and a nestbox - 10 years to switch to less intensive methods. Without this phased withdrawal period their poultry industry would have simply collapsed.
Yet even if Britain's poultry farmers were to return to the old-fashioned free-range days tomorrow, it would simply replace one set of welfare problems with another. Free-range flocks are prone to feather-pecking and cannibalism, which do not occur in battery systems at all.
More startling still is increasing evidence that free-range hens run the same risk of broken bones as battery hens and broilers. It is still not clear why this should be, or even if space is a factor. But it does force us to re-examine more closely the quality of life we offer our food animals.
At Oxford University Marion Dawkins, author of "Animal Suffering" and one of Britain's most respected ethologists, has been trying to find out exactly what goes on in the bird brain of a battery hen.
In doing so she has already overturned one popular misconception. Chickens, it seems, are much brighter than we have been led to believe. The average hen has an IQ at least as good as that of a laboratory rat. It can perform simple pecking tasks to win food and can recognise each individual bird within its social group.
Hens are also better at recognising individuals from within a group of pigeons than the pigeons themselves.
Her recent work has involved trying to establish what might be termed the luxuries in a hen's life, and what are necessities. A luxury is defined as something the hen would like if it was offered the choice - perhaps a different diet - but which it doesn't want strongly enough to work for. A necessity is something it will work for.
Leaving aside the obvious necessities of food and drink, the first priority in a hen's mind seems to be the need to forage - something it will pay quite a high price in terms of effort to obtain. However, its attitude remains intensely practical, and it is interested in raking through litter only if there is food to be found.
Dawkins is also currently working on the vexed question of how much space a battery hen needs. The FAWC wanted a minimum of 600 sq cm but pressure from Brussels forced the government to set a much smaller figure of 450 sq cm. And in practice even this pitifully inadequate space is reduced still further by the presence of the egg guard, allowing each hen a mere 360 sq cm in which to live.
Dawkins's study, using an overhead camera, has shown that a hen needs more than 450 sq cm just to stand still, and that any other behaviour such as turning round or stretching its wings requires a great deal more. She refused to say what an ideal minimum should be, but agreed when questioned that 800-900 sq cm was probably "nearer the mark". If this is true, the case for banishing the battery cage is overwhelming.
