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Information Sheet
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Laying Hens Egg Production & Welfare --Disease -- Slaughter Introduction Laying hens are reared for egg production. There are approximately 29 million laying hens in the UK (1) and 300 million in the European Union, over 75% of these hens live in battery cages (2). From 2012 the 1999 Laying Hens Directive will prohibit the use of conventional battery cages but will permit the use of ‘enriched’ cages along with non-cage systems. In 2006 (UK), 63% of eggs came from caged hens, 5% from hens kept in barns and 32% from free-range hens, of which 5% were organic (1). Hens are descended from the red jungle fowl of Southern Asia (2). They are taken from breeding farms when they are 18 to 20 weeks old. The vast majority of these are put into cages, usually alongside 4 other birds (3), with a single cage housing the 5 birds averaging only 40 x 55 cm in size. 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 conditions (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, they are then considered ‘spent’ and slaughtered. All egg production systems involve the disposal of unwanted male chicks as they are of no use to 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. There is a 50/50 chance of a male chick being born and it is estimated that around 30 million 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 or dislocation of the neck (1). Other methods include decapitation, neck-breaking or suffocation. A limited number of the dead chicks are used as low-priced animal feed-stuff (at zoos and wildlife parks) with the remainder usually going into landfill. Conventional ‘unenriched’ cages Battery cages are arranged in rows of 3-6 tiers inside huge, windowless sheds. These can contain up to 30,000 birds. Heating, ventilation and lighting are all automatically controlled. Egg-laying is promoted by light and so artificial lighting is kept on for around 17 hours/day to help increase production. Feeding and watering is also automated. Feather pecking can be a major welfare problem in laying hens in both the caged and non-caged environments. In caged systems, as hens are unable to peck at the ground for food, they tend to turn on each other and peck out at one another’s feathers. Severe bouts of this can cause cannibalism and in order to keep this under control hens often have their beaks trimmed or are de-beaked when young chicks. This procedure involves cutting off the front one-third of the bill using a hot metal guillotine (without anaesthetic) (3). This is obviously very painful for the birds as the tip of the beak is well supplied with blood vessels and nerve endings. Studies have shown that 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. When not carried out by a veterinary surgeon then the person undertaking the procedure must be over 18 years of age and operators should be trained and continually evaluated. 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) encourages foraging and dust-bathing and therefore reduces the feather-pecking tendency (1). Overcrowding means hens are unable to exercise, combined with the constant demand for calcium required to produce eggs, results in weak, brittle bones which are prone to fracture. A 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 causing considerable pain and distress to birds. Painful bone fractures also occur when the hens are removed from cages or caught in barns and transported for slaughter as they are easily startled becoming frantic and trying to flap their wings. Proposed ‘Enriched’ cages Barn eggs / Percheries
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 Disease Avian Coccidiosis Bacterial infections Slaughter The Welfare of Animals (Slaughter or killing) (Amendment into the 1995 Regulations) (England) Regulations 2007 now permits the killing of ‘end of lay hens’ and end of life breeder hens by exposure to gas on the premises where they have been housed. It also allows the Secretary of State to authorise the killing of birds by exposure to gas elsewhere than in a slaughterhouse. The culling of ‘end of lay hens’ on the home farm could dramatically reduce the incidence of welfare insults they experience because of catching and transport (1). Those reaching the slaughterhouse are removed from their crates and hung upside down shackled by their feet to a moving line whilst still fully conscious. Their heads and neck are dragged through an electrically charged water bath designed to stun the birds, rendering them unconscious. The moving line then takes the birds to an automatic neck cutter. Birds are then bled before entering a scalding tank to make the plucking easier. Birds often experience pain and struggle while hung in shackles, and they may suffer during the slaughter process. It is essential that a sufficient stunning current is used and that both carotid arteries (the major blood supplies to the brain) are cut to reduce the risk of birds regaining consciousness during bleed-out and subsequently entering the scalding tank whilst still alive. References and Useful Links 1. Department for Environment Food and Rural Affairs www.defra.gov.uk/ 2. Compassion in World Farming. 2007. Alternatives to the barren battery cage for the housing of laying hens in the European Union. 3. D’Silva. J. 2006. Adverse impact of industrial animal agriculture on the health and welfare of farmed animals. Integrative Zoology. 1:53-58. 4. The Battery Hen Welfare Trust. 2007. http://www.thehenshouse.co.uk/factsandfigures.html 5. Duncan. I.J.H., Slee. G.S., Seawright. E., and Breward. J. 1989. Behavioural consequences of partial beak amputation (beak trimming) in poultry. British Poultry Science. 30: 479-88. 6. McCoy. M.A., Reilly, G.A.C., and Kilpatrick. D.J. 1996. Density and breaking strength of bones of mortalities among caged layers. Research in Veterinary Science. 60: 185-6.
Further Information
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