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.
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
(Requirements as from 1st January 2003, these cages will be banned from 1st
Each hen is given 550cm2 of cage area, (less than an A4 piece of paper), in
which to move around. Until the 31st December 2011, whereby new regulations
come into force, a stocking density of 12 hens per square meter is allowed (1).
This ultimately leaves the hens with no room to flap and stretch, no means
to bathe in dust, no perch and no nest to lay an egg in. (4). Therefore
hens kept in conventional cages are unable to fulfil their 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 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.
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).
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
Proposed ‘Enriched’ cages
(All newly built cage systems must be of an enriched type. These are the only
cage systems allowed after 1st January 2012)
Each hen must have at least 750cm2 of cage area, (600cm2 of this must be useable)
the minimum cage height at the lowest point in the usable area is 45cm and
no cage shall have a total area that is less than 2000cm2. Cages must have
a nest, litter, perches, feed trough and drinking systems. These measurements
however still fail to allow adequate space for the hens to perform many important
natural behaviours (2).
eggs / Percheries
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. All newly built/rebuilt production units from
1st January 2007 must comply with the following stocking densities;
sites stocked prior to 3rd August 1999 until 31st December 2011,
12 hens per square meter.
- sites stocked between 3rd August 1990 until 1st January 2002, 12 hens per
square meter until 1st January 2007.
- new sites, no more than 9 hens per square meter usable area.
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.
Eggs produced in these systems must come from establishments which satisfy
the following conditions; hens have continuous access to open-air runs
which are covered in vegetation and there must not be more than 2,500 hens
per hectare of ground or one hen per 4m2 at all times. The birds must have
continuous access to open-air runs which means the sheds buildings have
a number of exits from the hen house (pop-holes). 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.