In this fact sheet: Egg production & welfare, Disease, Slaughter, References
Laying hens are reared for egg production. There were nearly 35 million laying hens in the UK in 2012 (1) with 31 million eggs eaten in the UK every day. In 2012, 48.5% of eggs came from caged hens, 3.5% from hens kept in barns and 48% from free-range hens, of which 2.5% were organic (7).
In 2012 the Welfare of Laying Hens Directive banned the use of conventional 'battery' cages replacing them with ‘enriched’ cages which increase the space and facilities for hens.
Egg production & welfare
Hens descend from the red jungle fowl of Southern Asia (2). They are taken from breeding farms at 18 to 20 weeks old. The majority of these are put in cages (3). Each hen can produce 300 eggs per year. On average a caged hen lays only 15 more eggs a year than a hen that has been kept in a barn or free-range system (4). This compares with only 12-20 eggs produced each year by their wild ancestors. After 12 months the hen’s egg-laying ability starts to decline and they are considered ‘spent’ and slaughtered.
All egg production systems involve the disposal of unwanted male chicks because they cannot be used in the industry. Male chicks from selectively bred egg-laying strains are not suitable for meat production and so are killed at 1-3 days old. It is estimated that around 30 million male chicks are destroyed annually by a number of permitted methods. These include the use of mechanical apparatus producing immediate death (such as a homogeniser which minces up chicks alive), exposure to gas mixtures, dislocation of the neck, decapitation, neck-breaking or suffocation (1). A limited number of the dead chicks are used as low-priced animal feed-stuff for zoos and wildlife parks, with the remainder usually going to landfill.
New ‘enriched’ cages are the only type of cage now allowed in the EU and have replaced 'battery' cages. Each hen must have at least 750cm2 of cage area and a minimum cage height of 45cm. No cage should have a total area less than 2000cm2. Cages have a nest, litter, perching space, a scratching area and a feed trough and drinking system (7). However, these measurements still fail to allow adequate space for the hens to perform many important natural behaviours (2).
Battery cages, which are now banned, had a stocking density of 12 hens per square metre (1) which left them with no room to flap and stretch, bathe in dust, perch or use a nesting area (4). Cages were arranged in rows of 3-6 tiers inside huge, windowless sheds containing up to 30,000 birds. Heating, ventilation, lighting, feeding and watering were automatically controlled. Egg-laying was promoted by light and artificial lighting was kept on for 17 hours a day to help increase production. Hens were unable to fulfil their basic behavioural needs and the resulting frustration led to aggression.
Feather pecking can be a major welfare problem in laying hens in both the caged and non-caged environments. In caged systems hens are unable to peck at the ground for food so they tend to peck at one another’s feathers. Severe cases of this cause cannibalism and to keep it under control hens often have their beaks trimmed or are de-beaked when young chicks. This painful procedure involves cutting off the front one-third of the bill (which contains blood vessels and nerves) using a hot metal guillotine without anaesthetic (3). Studies have shown this causes both immediate and enduring pain (5). Birds may not resume normal pecking or preening for as long as six weeks after de-beaking, and in some cases profuse bleeding and death from shock occurs. Beak trimming should, whenever possible, be restricted to beak tipping (the blunting of the beak to remove the sharp point). Research indicates that the availability of good quality litter, such as shavings encourage foraging and dust-bathing and reduces the feather-pecking tendency (1).
Overcrowding hinders hens from exercising and this combined with the constant demand for calcium to produce eggs, results in weak, brittle bones prone to fracture. One study showed that approximately 35% of all mortalities among caged hens were attributable to bone fragility, known as cage layer osteoporosis (6). This high incidence of broken bones is a severe welfare problem. Painful bone fractures also occur when hens are removed from cages or caught in barns and transported to slaughterhouses. They are easily startled becoming frantic and trying to flap their wings.
Barn eggs come from hens kept inside large windowless barns where they can roam freely and have several rows of perches at different heights. Litter such as wood shavings or straw needs to cover at least one their of the floor, and nest boxes must be provided. Barns are often old battery sheds that have been converted. All barns have a maximum stocking density of 9 hens per square meter of usable area (7). 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 bird’s faeces.
Free-range eggs are produced under the highest animal welfare conditions. Hens must have continuous access to open-air runs which are covered in vegetation. There must not be more than 2,500 hens per hectare. The shed buildings must have a maximum stocking density of 9 hens per square metre of useable area and must have a number of exits, known as pop-holes. However, inadequate numbers of pop-holes in large sheds may mean that some birds may never leave the sheds. Pop-holes may also be protected by more aggressive birds discouraging other hens from using them freely (7). Overcrowding inside the sheds can lead to similar welfare problems as other systems with aggression, feather-pecking and cannibalism occurring.
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