Animal Aid

From Shell to Hell: the modern egg industry

The modern chicken is descended from the Red Junglefowl (Gallus gallus) of Asia and has been domesticated for around 8000 years. During the breeding season, the hens would lay 5-6 eggs in a clutch before incubating them for 18-20 days (del Hoyo et al, 1994). Compare this with modern breeds of domestic hen, which lay more than 300 eggs in a year.

In the wild, hens are active from dawn to dusk, walking, running, pecking and scratching in the ground for food, dust-bathing and nest-building. Their natural lifespan is up to ten years. Chickens farmed for meat are killed when they are six weeks old. Egg laying hens are killed when around 72 weeks of age.

The modern poultry industry

Meat production

These days, the poultry industry is divided into two areas: egg production and meat production. Meat - 'broiler' - chickens have been manipulated, through selective breeding techniques, to make them grow around twice their natural rate, to get them as fat as possible in as short a period of time. They grow so big, so fast, their legs are unable to support their weight and they frequently collapse. Broiler chickens are slaughtered at six weeks of age - they are still babies, trapped inside obese, deformed bodies.

'Farm fresh', 'country fresh' and 'fresh from the barn' 
              are all terms conjured up to disguise the cruelty involved in egg 
              production. You think eating eggs is a cruelty-free option? Think 

Egg production

Egg-laying hens are a different 'type' of chicken to broilers. Bred specifically for high egg production, they do not put on weight quickly enough to be considered economically-viable for meat production. A particularly tragic occurrence springs out of this difference: the destruction of male chicks, deemed useless because they cannot lay eggs but are not suitable for meat production either (see below).

Despite centuries of domestication, laying hens retain the natural behaviours shown by their wild ancestors. This 'ancestral memory' of the birds' natural way of life has been carried down the generations so that hens retain the need to carry out behaviours such as building a nest, perching, pecking and scratching at the ground, dust-bathing, etc. (Dawkins, 1993). For the majority of the world's egg-laying hens, the farming system renders it impossible to live anything remotely resembling a natural lifestyle.

The global egg industry

Around the world there are approaching 5000 million egg-laying hens. The latest numbers available show that China had the largest flock (800 million), followed by the European Union (271 million), the USA (270 million), Japan (152 million), India (123 million) and Mexico (103 million) (IEC, 2001).

Globally, between 70-80% of laying hens are housed in battery cages. The proportion of caged hens in the EU is about 90% (Williams, 2000).

There are about 30 million hens in the UK egg-laying flock. Some 66% are currently in cages, 27% kept free range; and 7% in perchery/barn systems (BEIS, 2005).

UK laying hens currently produces around 10,000 million eggs. In the UK, the average consumer eats 170 eggs per year.

Caged chickens

Labelling: what does it really mean?

The egg industry has created a very successful smoke-screen to hide the harsh reality of modern egg production by using terms such as 'farm fresh' and 'country fresh'. As with 'free range', these misnomers conjure up images somewhat different from the true picture. One would not normally describe eggs covered in excrement, lying amongst the decomposing bodies of dead hens in battery cages as 'fresh'!

From 2004, European Union legislation will make the egg industry more transparent when it becomes compulsory for eggs to be labelled according to the method of production. The following terms will apply:

  • Battery eggs will be labelled "Eggs from caged hens";

  • Barn eggs will be labelled "Barn" eggs;

  • Free-range eggs will be labelled "Free Range" eggs.

Farming systems for eggs

Battery Cages

Battery farms consist of huge, windowless sheds housing thousands of hens who are crammed four or five at a time into small wire cages stacked on top of each other in rows. The hens are put in to the cages at around 18 weeks old and will not come out again until they go for slaughter (around 72 weeks of age).

In battery units, four or five hens are crammed into a space 
              not much bigger than a microwave oven. They are barely able to move, 
              let alone stretch their wings.

Battery cages are one of the factory farming industry's most cruel inventions. Each hen has 450cm² of space - the equivalent of an A4 sheet of paper. The average wing span of a hen is 76cm - the cages are so small that the hens will never be able to stretch their wings, raise their heads properly or move freely, and because they are barren the birds cannot exhibit any of their natural behaviours such as dust-bathing or building a nest. Free-range birds have been found to spend half their time freely feeding and foraging (Appleby & Hughes, 1991). Battery hens are denied the ability to do either.

Most intensive egg farms are fully automated - everything from the lighting to the feeding, watering and egg collection is controlled automatically. The cage floors slope forward so that eggs roll on to a conveyor belt and are taken away to be boxed. In order to promote egg-laying, the sheds are artificially lit for approximately 17 hours each day, with the lights coming on at around 3am.

Keeping animals in such confined, overcrowded conditions obviously has serious implications for their welfare and health. Unable to perform their natural behaviours, the bodies of battery hens degenerate through lack of exercise. Unable to scratch at the ground, their claws overgrow and may curl round the wire mesh of the cage.

Hens in traditional battery cages perform 'vacuum' dust-bathing, i.e. mimic the actions of dust-bathing even though they have no 'dust'. This behaviour is abnormal and the frustration of hens' normal dust-bathing behaviour is recognised as a source of suffering (Baxter, 1994).

Hens are frequently cannibalised or crushed to death by their cage-mates. The decaying corpses of dead birds are not always removed as farm workers do not see them lying at the back of the cage. The top and bottom rows of cages, potentially housing thousands of birds, are particularly difficult to view simply because they are not at eye level and involve either bending down or standing on something to look inside. Battery farms are frequently staffed by only a few people. If enough staff were employed to enable each cage to be inspected each properly, the battery system would no longer be financially-viable due to the high cost of staffing.

Battery cages are so inhumane that they will be banned in 
              the EU from 2012. But that means years of suffering ahead, and the 
              replacement - so-called 'enriched' cages - will make little difference 
              because a cage is still a cage and the extra space the hens will 
              have is equivalent to the size of a postcard.

Barn (perchery) systems

Eggs labelled 'barn' are laid by hens who are not caged but are confined to a shed, often in filthy, stinking cramped conditions. The birds may be able to stretch their wings - and are therefore probably slightly better off than battery hens- but they will never see daylight or breathe fresh air and are still denied real freedom, comfort or ability to exercise their natural instincts. Flock sizes can be huge, with some barns housing up to 16,000 birds. The name 'barn' is used to deliberately mislead the public into thinking the hens are kept in bright, airy conditions with fresh straw on the floor. Not true!

Free Range Systems

Many people associate the term 'free range' with 'cruelty free' and assume the hens live a natural lifestyle, merrily pecking at the ground, willingly giving the farmers the daily gift of an egg. Unfortunately, this is not the case!

The EU guidelines, to which egg farmers are legally obliged to adhere (Welfare of Laying Hens Directive), state that in order for eggs to be labelled 'free range', the hens must have access to an outdoor range area, accessible through openings in the sides of the barn. The barn can be stocked at a density of 12 hens per m² (hardly a lot of space!), and the total opening between the barn and the outside must not be less than 2m per 1000 hens. Farmers with fewer than 350 birds in their flock are exempt from the Welfare Directive (unless their eggs are sold graded as Class A).

The reality is that 'free range' hens are often kept in 'barn'-type sheds in flocks of up to 16,000. In large-scale free range units, often fewer than 50% of the birds regularly go outside. Some barns, for example, only have doors down one side - imagine the scrum trying to get through the holes to the outside; the hens at the back of the barn are unlikely ever to be able to pick their way through.

Free range hens are frequently debeaked (see below), and, as with all commercial laying hens, they are usually slaughtered after one year of egg production.

Barn hens are still confined to dirty, overcrowded sheds. 
              They will never see daylight, breathe fresh air or be able to exercise 
              their natural instincts.

European Scientific Veterinary Committee Report: an admission of cruelty

In 1996, the European Union's committee of scientific and veterinary experts published a report acknowledging the behavioural needs of hens and the welfare problems caused by caging. The report recognised that:

  • "Hens have a strong preference for laying their eggs in a nest and are highly motivated to perform nesting behaviour."

  • "Hens have a strong preference for a littered floor for pecking, scratching and dust-bathing."

  • "Hens have a preference to perch, especially at night."

All of these behaviours are denied to caged hens. The report's conclusions were:

"Battery cage systems provide a barren environment for the birds... It is clear that because of its small size and its barrenness, the battery cage as used at present has inherent severe disadvantages for the welfare of hens."

1999 Laying Hens Directive

In 1999, the European Union announced that conventional battery cages would be banned from 2012. The new Laying Hens Directive (Council Directive 1999/74/EC) also forbids the introduction of newly-built battery cages from 2003, and requires, until the complete phase-out, that the space allowance in existing conventional battery cages be increased from 450 cm² to 550 cm² per bird. Whilst a minor improvement, to put these space allowances into context, an A4 sheet of typing paper covers 620 cm².

Many people associate 'free range' with 'cruelty-free' and 
              assume the hens live a natural life. The reality is very different.

'Enriched' cages

The proposed replacement for battery cages is the 'enriched cage', which is slightly bigger and taller than a battery cage and will contain some 'furniture' such as a shared perch and nest box, plus litter and a claw-shortening device. However, a cage is still a cage, despite these changes, and the caged hens will still be denied the ability to exercise their instincts and fulfil their natural needs.

The actual usable space allotted to each bird in an enriched cage will be 600 cm² - in effect the increase in space the hens will have is equivalent to the size of a postcard. Furthermore, consider that the average hen at rest occupies 600 sq. cm (Dawkins & Nicol, 1989) - enriched cages, therefore, still only offer the absolute minimum space required by a hen lying down.

The introduction of enriched cages also has the potential to create further welfare problems for the hens on top of those already associated with being kept in such intense captivity. Due to the severely restricted space they are confined to, the birds are already in constant contact with each other and the sides of the cage, the addition of furniture gives them another obstacle to brush up against. Feather loss is generally worse in cages due to a combination of abrasion from mesh and feather pecking (Appleby & Hughes, 1991; Rollin, 1995). Indeed, the provision of furniture actually carries the disadvantage of increasing the amount of potential abrasive surfaces and obstacles to free movement in the birds' environment.

Problems such as feeding birds being scratched by the claws of perching birds and build-up of droppings under perches indicate the problems of introducing 'enrichment' in a confined space (Walker, 2001).

It is a travesty that one cage system is going to replace another, but egg producers are desperate to keep their production costs down - to keep the consumers happy - and caging birds is, unfortunately, the most economical way of rearing them.

Each year in the UK, approximately 30 million day-old male 
              chicks are gassed or tossed alive into giant industrial shredders 
              - 'disposed of' because they are unable to lay eggs and are considered 
              too scrawny a type of chicken for meat production.

Health problems associated with egg-laying hens

The laying ordeal

Factory-farmed hens lay eggs five or six times a week. The hens become highly stressed and aggressive during the pre-laying period because of lack of privacy and nesting materials. When an egg is produced, the hen's vent becomes distended, red and moist, attracting the attention of bored and frustrated birds. Vent pecking can occur, and even lead to cannibalism.

The unnaturally high level of egg production also contributes to osteoporosis (see below) as calcium is drained from the hens' bodies for the production of egg shells, often leading to severe osteopenia (RSPCA, 1989).

Brittle bones

Battery hens suffer Caged Layer Osteoporosis (CLO), or brittle bones. Research has shown that 35% of premature deaths in cages are due to CLO, a slow death from paralysis and starvation at the back of the cage. This is clearly illustrated by the fact that, because of their ability to move about, non-cage birds may have 41% more tibia strength than those raised in cages (Meyer & Sunde, quoted in Appleby & Hughes, 1991).

Injured feet

Confined to the cage, the hen is unable to forage by scratching and pecking at the ground. Denied this simple activity, the hen's claws can grow long or twisted and be torn off; or even grow around the wire mesh of the sloping cage floor. The slope itself puts painful pressure on the hen's toes, causing damage to the bird's feet.

This shocking photo shows chicks being sorted, prior to 
              the males being gassed.

Malignant tumours

Another welfare problem associated with pushing hens to lay increasing numbers eggs is the development of malignant tumours of the oviduct. In one investigation, a significant proportion of malignant tumours of the oviduct were identified in 20,000 'spent' layers selected from ten different farms. The researchers concluded, "... the increase in the prevalence of the (magnum) tumour coincides with continued selection of fowl for high egg production" (Anjum, 1989).


As often occurs with all other intensively-farmed animals, the stress of living in such unnatural, cramped conditions causes hens to behave aggressively towards one another. Hens frequently exhibit the abnormal habits of pecking at each other and pulling one another's feathers out. In extreme cases this can lead to cannibalism. In an attempt to curtail this behaviour, chicks are routinely subjected to the mutilation of debeaking.

The industry describes the practice as 'beak trimming' but it is much more than that. A sharp, hot blade will slice off the end of the chick's beak. Sometimes a chunk of face may be sliced off too as the birds are shoved without care into the slicing machine.

Egg producers will maintain that debeaking is no more painful to a bird than cutting nails is to humans, but scientific evidence proves that hens not only feel pain at the time of the operation but can also suffer a lasting, chronic pain.

The slaughter of male chicks

Chick hatcheries breed one or other strain of chick depending on which industry they supply - egg or meat. Male chicks born of the egg-laying variety are deemed useless because they cannot lay eggs, but are no good for meat production either. Each year, approximately 30 million day old male chicks are 'disposed of'.

Eggs contain saturated fat, one of the main causes of heart 
              disease - and they are among the highest sources of dietary cholesterol.

At the hatcheries, eggs laid by breeding hens are taken away to develop inside giant industrial incubators. Once hatched, the newborn chicks pass down a production line to be sexed and sorted. Sick, weakly and male 'reject' chicks are pulled out and thrown into giant sacks or crates. Some are crushed to death or suffocate. The chicks' next stop is either the gas chamber or the macerator - a giant mincing machine - into which they are tossed alive.

The slaughter of 'spent' hens

Most egg-laying hens (including free range) are slaughtered at around 72 weeks of age, because, as their egg production drops, they are not considered profitable enough to keep alive.

The transport and slaughter of hens is an incredibly traumatic experience. Once caught, the hens are held upside down, several per hand, and carried out to be packed into crates for transport. Rough handling and complete disregard for their welfare often leads to them breaking bones in the process (Turner & Lymbery, 1999). One study found that at the time of catching and crating, levels of the stress hormone corticosterone in battery hens were ten times higher than normal.

On average, 29%, of battery hens arriving at the slaughterhouse are reported to have at least one freshly-broken bone. Removing the birds from the crates and hanging them upside down to await slaughter increases the proportion of hens with broken bones to 45% (Gregory and Wilkins, 1989; Gregory, 1994).

The slaughter process for hens is the same as for all poultry: they are shackled upside down, dunked into an electrified waterbath to stun them, dragged past either a slaughterman with a knife or an automatic rotating blade to have their throats slit, and then dipped into a 'scalding tank' to loosen their feathers. Birds may 'swan neck' (raise their heads) causing them to miss the stun bath and may have their throats cut whilst fully conscious. Some birds may not have their throats cut properly, meaning they are still alive when they enter the scalding tank.

'Spent' hens can be worth as little as two pence per bird. Their carcasses will be used in cheap products such as chicken soups, pastes, pies, pet food, etc.

Research indicates that eggs can inhibit the absorbtion 
              of iron (needed for healthy blood, cells and nerves) and contribute 
              to the loss of calcium (necessary for healthy bones).

The impact of eating eggs on the environment

Farming hens for their eggs is a huge waste of resources. It takes 3 kilos of grain (in the form of chicken feed) to produce one kilo of eggs. This is because the conversion of crops by farm animals into food for humans is grossly inefficient. And it is not only food (grain) that is wasted. Each battery egg takes approximately 180 litres of water to produce. This is a shocking statistic considering the volumes of water human beings use in developing countries: in India, for example, the poorest people use an average of only 10 litres of water each per day (O'Brien, 1998).

Studies of farm animal housing have shown that egg farms have one of the highest farm emission rates of ammonia gas, a serious environmental pollutant linked to acid rain.

Health hazard!

Eggs - in particular, raw eggs - can be a cause of salmonella food poisoning.*

In 2003, there were 9,743 laboratory-confirmed cases in the UK of salmonella enteriditis, a pathogen commonly linked to the consumption of eggs. Between 1992-2002, of 143 outbreaks of food-borne Infectious Intestinal Disesease (food poisoning) where eggs were reported as the vehicle of infection, 124 were caused by salmonella entiriditis. (By definition an outbreak involves more than one person with an established link between the cases.) (PHL 06.01.04)

Advice from the Government's Food Standards Agency (FSA) is that "eating raw eggs may pose a health risk. Vulnerable groups such as the elderly, the sick, babies and pregnant women should only consume eggs that have been cooked until the white and yolks are solid" (FSA, 2001).

There are no nutrients in eggs that cannot be obtained from 
              other foods. Cutting out animal products entirely is the <em>really</em> 
              healthy option.

* Nowadays, the majority of - but not all - eggs on sale in the UK bear the Lion Brand stamp of approval which means they have come from hens who were vaccinated against salmonella. However, the data show that salmonella clearly has not been eliminated.

Not all they're cracked up to be

Eggs are high in saturated fat and cholesterol - one of the main causes of heart disease. Eating protein-rich animal products can actually cause calcium loss: for every 100g of egg consumed, 20mg of calcium is lost. Eggs also stop our bodies from absorbing plant-derived iron. There are no nutrients in eggs that you can't get from elsewhere. In fact, cutting out animal products entirely is the really healthy option.

With grateful thanks to the following groups who supplied much of the information for this factfile:

The Vegan Society
Farm Animal Welfare Network

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