In June 1999, it was announced that battery cages would be banned throughout the EU. Although the ban will not take effect until 2012, the phase-out process will begin in 2003.
The intensive overcrowding and barren environment faced by battery hens means they are prone to a wide range of welfare and disease problems.
Hens kept in battery cages are unable to fulfil basic behavioural needs such as wing-flapping, dust-bathing, scratching, pecking, perching and nest-building. The resulting frustration and stress leads to aggressive behaviour such as feather-pecking and cannibalism.
Cages prevent hens from dust-bathing. Despite this, caged hens will attempt to dustbathe on the wire floors or on other birds. This is called vacuum dustbathing. Such stereotyped behaviour is common amongst battery hens. Pecking and scratching for food is also impossible. Hens naturally spend a great deal of time pecking at objects. Hens in cages have nothing to peck at and so may peck cage fittings and each other. Feather-pecking is a major problem in cages. Many hens eventually lose all their back feathers as these are easy targets for other birds. As birds are unable to escape one another, feather-pecking can escalate into increased aggression and cannibalism.
In an attempt to prevent feather-pecking, many hens undergo debeaking or beak-trimming when young chicks. This involves cutting off about one-third of the bill using a heated blade without anaesthetic. This is obviously very painful for the birds and studies have shown that the pain lasts for a prolonged period if not indefinitely. Birds may not resume normal pecking or preening for as long as six weeks after debeaking, and in some cases profuse bleeding and death from shock occurs.
Hens show elaborate nest-searching and nest-building behaviour given the opportunity. Caged hens have no nesting material and no quiet, dark place in which to lay. Hens become frustrated and aggressive prior to lay and may attempt to hold back egg-laying.
Unchecked growth of claws is another problem faced by battery hens. Normally their claws would be worn down by walking and scratching. This is not possible in battery cages and so claws may grow and become entangled in the wire floor. This can prevent birds from reaching food and water, causing death from hunger or thirst.
Damage to feet and claws can also result from having to continually stand or crouch on thin wire floors, especially as these are generally sloped. Steep sloping floors lead to high levels of foot deformities as birds are more likely to slip.
Overcrowding means hens are unable to exercise. This results in weak, brittle bones which are prone to fracture. A study by the Agricultural and Food Research Council in 1992 found that one-third of laying hens in cages suffered broken bones by the time of slaughter. The high incidence of broken bones is a severe welfare problem causing considerable pain and distress to birds. Most bone fractures occur when the hens are removed from cages and transported for slaughter.
Bone fractures also occur when hens are disturbed. Because of their barren and monotonous surroundings battery hens are easily startled and are prone to hysteria. Hens become frantic and try to flap their wings and hide at the rear of their cages. This can spread through whole sheds and lead to a high incidence of injuries.
Disease can also be a problem in battery farms. Infectious bronchitis, cage layer fatigue, leukosis and egg peritonitis are just some of the diseases prevalent in battery systems. Many hens are infected with salmonella and campylobacter though they may not show any symptoms. This can cause severe food poisoning in humans following consumption of contaminated eggs.
Mortality in battery cage flocks is around 6% per year. Removing the dead is a daily process in many battery farms. The design of battery sheds means many dead can remain unnoticed, especially on the top and bottom tiers.
The two main alternatives to battery cages are percheries and free-range systems. Whilst these are preferable to battery cages both can have considerable welfare problems.
In percheries, the hens are kept in large windowless sheds with several rows of perches at different heights. The floor is likely to be at least partly covered with litter (wood shavings or straw) and nest boxes are provided. Percheries are often old battery sheds that have been converted. Eggs from percheries are called barn eggs.
EC regulations mean hens can be stocked at 25 hens per square metre floor space with 15 cm perching space per bird. This can create stress from overcrowding leading to aggressive behaviour, feather-pecking and cannibalism. Debeaking is common in perchery systems. Another problem of overcrowding is birds crashing into one another whilst attempted to land on perches. 25% of perchery hens may have broken bones before transport to slaughter due to flight and landing accidents. This is a much higher level than either battery or free-range hens.
Many birds are unable to lay eggs in nest boxes and so lay them on the floor where they may be eaten by other birds or become contaminated due to contact with the birds faeces. Disease is also a major problem. Coccidiosis, foot infections and other diseases can be widespread in large flocks.
Commercial free-range systems involve massive flocks, often around 15,000 birds, which are housed in huge sheds. The birds must have continuous access to open-air runs which means the sheds have a number of pop-holes. Stocking densities must not be more than 1,000 birds per hectare of ground to which the birds have access. This is about 200 times more space than battery hens have. However, inadequate numbers of pop-holes in large sheds may mean that many birds never leave the sheds. Pop-holes may also be protected by more aggressive birds discouraging other hens from using them freely.
Overcrowding inside the sheds can lead to similar welfare problems as percheries with aggression, feather-pecking and cannibalism all occurring. Debeaking is more common in free-range hens than battery hens. Disease is also a problem, especially where high stocking densities result in the ground outside becoming heavily fouled.
Traditional free-range involves smaller flocks which are housed in moveable houses.
All egg production systems involve the disposal of unwanted male chicks. Male chicks from selectively bred egg-laying strains are not suitable for meat production and so are killed at one to three days old. Killing is usually by carbon dioxide gassing though other methods include decapitation, neck-breaking or suffocation. Slaughtered chicks may be added to feed or used as fertiliser.
Information from the Vegetarian Society UK. For more details look at their website.