Plucked from the jungles of south-east Asia, chickens
have been kept by humans for at least 4,000 years. At
first they were bred for cock fights, so were a source
of gruesome entertainment before they were killed for
food. The past 50 years have seen dramatic changes in
the way chickens are kept and their body shape has been
drastically altered by genetic selection. But, as breeding
has focused on physical production, their biological
instincts remain. When returned to the wild, domestic
chickens soon begin to behave like their jungle-fowl
Broiler chickens are the most widely farmed animal.
40 billion are killed worldwide every year. Over 800
million are killed in the UK annually. Broiler rearing
is now the most intensified and automated type of livestock
production. In 2006, the overall UK chicken industry
was worth £3 billion in the UK (9).
A typical broiler chicken spends his life in a windowless
shed with thousands of other birds. Todays chickens
are slaughtered when their eyes are still blue and they
cheep - chicks in an obese adult body. In
natural conditions, birds of this age would still be
sheltering under their mothers wings. Decades
of selective breeding has resulted in this forced growth
rate, producing faster growing chickens for greater
profits with no regard for animal welfare. Many broilers
can no longer support their own body weight and most
suffer from leg disorders. The crippled birds die from
starvation and dehydration as they are unable to reach
food and water points. Millions suffer from diseases
brought on by the squalid conditions inside the factory
The broiler shed
98% of broiler production in the UK is intensive (2).
Each shed usually houses 30,000 chickens or more. One
day old chicks are put into the sheds and housed there
until they are slaughtered 6 weeks later. Large numbers
of birds being housed together makes them susceptible
to heat stress. Heat stress causes suffering and death
in birds (8).
Lighting in broiler sheds
Most broilers are reared indoors without windows under
dim artificial light. Many are kept in near-constant
light because this is believed to increase feed intake.
The lighting is kept dim because this discourages unnecessary
activity, thus maximising growth. Scientific evidence
shows that preventing broilers from having a proper
night period adversely affects their welfare. Evidence
shows that lack of sleep reduces an animals ability
to cope with stressful conditions. The low level of
activity shown by broilers reared under dim lighting
is likely to predispose them to leg disorders. Continuous
lighting programs also cause eye abnormalities (11).
Problems with high stocking densities
In the UK, the suggested maximum stocking densities
are 34kg/m squared (approx. 17 birds per metre squared)
(11) but most producers stock at even higher densities
than this as there are no legally-binding regulations. The UK government suggests no more than
34kg but even this is too strict for the industry, which
sets itself a limit of 38kg (14). The EU science
committee said that the stocking density must be no
higher than 25kg/m (about 12 birds) per square metre
'for major welfare problems to be largely avoided' (Defra's
guidelines for free-range broilers are not more than
27.5kg/m, so even these do not meet the European
suggestions). As a guideline, each
bird in an intensive house has less space than an A4 piece of paper. In general,
as stocking density increases management standards worsen.
For example, regular inspection to monitor flock health
and remove dead or injured birds is difficult without
causing panic and more injury (12). Severe overcrowding
leads to a build-up of infectious agents and serious
welfare problems such as breast blisters, contact dermatitis
and leg disorders (5).
New legislation that sets out minimum standards for
the protection of chickens reared for meat will
become legally binding in 2010, and will bring common
standards for the treatment of chickens across Europe.
This is the first piece of legislation that specifically
concerns chickens raised for meat and therefore the
first time that the chicken industry has had legal
guidelines to stick to in regards to stocking density.
However, this Directive will permit producers to stock
chickens at 42kg per square metre (21 birds per square
metre), a density far higher than recommended for better
welfare and even higher than the one currently set by
the British poultry industry!
Poor litter management
Broiler chickens spend their entire lifetime without
having their bedding changed. As a result, the ground
inside the sheds quickly becomes soiled and wet. When
on poor litter, broilers are susceptible to pododermatitis
(foot-rot) and burnt hocks. Litter becomes wet due to
air change rate; litter material and depth; stocking
density and diet and health of the birds (7).
Any farm that feels that it must undertake mutilations
of animals to prevent them injuring one another has
very poor management systems.
Debeaking - When chicks are only a few days old,
their beaks can be partially amputated, a section of
the upper beak being cut off with a red-hot blade or
with clippers. Beak trimming is painful and can result
in permanent pain. Ex- farm and slaughterhouse worker,
Colin Ryder says the following, The correct hot
knife was, in the time I was there, never used. Anything
to hand was used for beak trimming. I have witnessed
nail scissors, toe clippers etc being used. I have on
occasion done this. I have seen chicks with blood spurting
out of their beaks as they cheeped. I have
witnessed a couple of hundred birds subsequently die
because of one member of staff cutting too much beak
Dubbing - Involves the removal with scissors
of the birds comb (fleshy red crest on the head of the
chicken). Dubbing is said by vets to cause stress and
unnecessary mutilation (Blacks Veterinary Dictionary).
It is carried out to prevent birds from pecking each
others combs and to discourage cannibalism which only
occurs in overcrowded conditions.
Toe cutting - The last joint of the inside toe
of male breeding birds is sometimes removed. This can
result in open wounds, blood loss and pain. This mutilation
is performed to avoid injury to hens during mating.
Dewinging - When farmers want to prevent chickens
from flying, dewinging is carried out. The flight feathers
of one wing are clipped.
Leg problems with broilers
In modern genotypes of broiler chickens, lameness inevitably
develops even though the birds are slaughtered at 41
days. Chickens are bred to gain weight so rapidly that
their legs are sometimes unable to support them properly.
In the worst cases they can only walk by crawling on
their shanks (part of the leg between the hock and the
ankle). Birds have been genetically selected to grow
rapidly resulting in abnormally high loads being placed
on relatively immature bones and joints (6).
Scientists have found that factory farmed chickens,
crippled through being forced to grow abnormally fast
in overcrowded conditions, will seek relief by choosing
to eat food containing pain-killer if given the chance
Catching the chickens
Teams of Catchers work at high speed to
load up huge transport lorries with the chickens when
they reach slaughter weight. Birds are grabbed
and carried, several in each hand, to be flung into
crates. Legs and wings often break and crippled birds
endure agony on the journey to the slaughterhouse. Colin
Ryder says, Catchers carry 2 bunches of hens by
one leg, upside down. When angry or behind schedule
I have seen the bunch hit against walls to stop them
squarking and flapping.
Over 700 million broiler chickens are transported by
road to slaughter plants in the UK every year (others
are slaughtered on farms). Many birds are transported
in modular systems in which 16-25 birds are placed in
each transport container or drawer. A vehicle
may carry up to 24 modules containing 12 drawers and
thus more than 6000 birds may be carried on a single
Catching and transport is incredibly stressful and
many birds do not reach the slaughterhouse alive (1.7
million birds a year) (1). Broilers have to cope with
withdrawal of food and water, acceleration and vibration,
noise and social disruption and hot and cold draughts
(1). Careless handling means that birds skulls
can be crushed and that dislocated hips are commonplace.
Inside the slaughterhouse, birds are shackled by their
feet. The process of hanging live birds upside down
prior to slaughter causes extreme stress and has lead
scientists to investigate alternative options for the
stunning and slaughter of poultry. Despite this, the
vast majority of birds in British abattoirs continue
to be shackled alive.
The shackle line carries the birds to the electronic
waterbath where they will suffer a painful electric
shock. Many birds do not get stunned due to not making
contact with the water. These birds are fully conscious
while they are having their necks cut. Even chickens
that are stunned often regain consciousness before reaching
the neck cutter.
After the birds throats are cut by the automatic
blades, they are moved on to the scalding tank, where
feathers are loosened prior to plucking. Some birds
are still alive at this stage if they have been missed
by the neck cutter and the back up
killer who manually breaks the necks of birds
missed by the machine. Birds will pass the back up killer
at a speed of up to150 birds a minute so he will only
have about half a second to check each one (12).
Broiler disease and mortality
Millions of chickens die every year from heart attacks,
fatty livers and kidneys, colisepticaemia (blood poisoning),
viral arthritis and perosis (displacement of the tendons
and inability for the leg to support the birds
weight). Mortality rates on British farms are about
5.1 per cent, which means that around 45 million
chickens in Britain die before they reach slaughter each
In the squalor of the broiler house infections spread
like wildfire. Salmonella, Listeria, Campylobacter and
botulism all thrive in the sheds. A huge percentage
of birds slaughtered for human consumption have these
diseases and chicken pieces are often the salvaged parts
of damaged or diseased birds that cannot be sold as
A report by Earthsave, What About Chicken?
said, Factory farms are fertile breeding
grounds for disease, and many commercial livestock feeds
are tainted with Salmonella. Additionally, todays
slaughterhouses do an excellent job of dispersing pathogens
from bird to bird. (3).
There are many other common diseases on the broiler
unit including the following:
Ascites - The right side of the heart becomes enlarged
due to its increased workload during the birds
rapid growth. The bird breathes quickly and the lungs
become congested. Liver function is affected, the abdomen
becomes swollen with fluid increasing the risk of heart
failure. Ascites is a major cause of death in broilers
- an estimated 4.7 per cent worldwide have the disease
Sudden Death Syndrome - is also a major cause of death
in broilers. SDS is acute heart failure. Symptoms are
sudden vigorous wing flapping, muscle contractions and
loss of balance. The birds often cry out then keel over
and die (11).
Skin diseases - The most common disorders are lesions
on the parts of the body in prolonged contact with litter,
mainly the feet, hocks and breast. These are known as
ammonia burns, hock burns ulcers or blisters. They are
often very painful and covered with crusts formed by
discharge and faecal material in the litter, and become
infected by a variety of bacteria and funghi. The ulcers
act as a gateway for infection, which can spread through
the bloodstream causing joint inflammations.
Scabby hip syndrome - Broilers are also prone to deep
dermatitis, causing swelling and inflammation below
the skin. This is commonly the result of scratches becoming
infected by bacteria, particularly Escherichia coli
(E. coli) which leads to scabby hip syndrome (11).
The use of drugs
Antibiotics and antimicrobials are routinely added to
chickens feed in a desperate attempt to control
the diseases that run rife in the broiler sheds. Scientists
warn that antibiotic resistant organisms have emerged
due to the over use of antibiotics on farm animals putting
human health and life at risk. The following are just
a small sample of drugs used:
Nicarbazin, shown to cause birth defects and hormonal
problems in animal studies, has never been carefully
evaluated for safety in humans. In 1999, 17.8 per cent
of chicken livers tested had residues of nicarbazin
in excess of the maximum residue limit (13).
Lasalocid is a member of the potent cardio-toxic ionophore
family of drugs and in 1999 was found in 12 per cent
of chicken muscle tested (13).
Dimetridazole (DMZ) is suspected of being able to induce
both cancer and birth defects, and is banned from
livestock feed in Canada, yet in 2000, 2.6 per cent
of broiler feed tested contained DMZ (13).
Health implications of eating chicken
A report by Earthsave says, Handling
chicken has gotten so precarious (Time magazine calls
raw chicken one of the most dangerous items in
the American home) even government officials recommend
treating poultry as if it were laden with lethal microbes.
A recent report summarizing 55 different studies found
that approximately 30 per cent of chicken is contaminated
with Salmonella and 62 per cent with its cousin,
Campylobacter. These two pathogens are responsible for
80 percent of the illnesses and 75 percent of the deaths
associated with meat consumption (USDA).
The situation in the UK is not much better. A report
in the Guardian in January 2000 revealed that two in
five poultry slaughterhouses are failing to comply fully
with hygiene requirements, and 40% of chickens contain
either the Salmonella or Campylobacter food poisoning
In an October 1996 Which? report, a random sample of
90 chickens were bought from major supermarkets and
butchers. Of these 32 were found to be unfit for human
consumption. Tests on a further 160 chickens revealed
that almost 20% contained Salmonella, while Campylobacter
was found in more than a third.
The poultry industry is guilty of having totally disregarded
bird welfare in its quest for fast bird growth and maximum
profits. It is not just the birds who are suffering
- diseases are spreading due to the overcrowded conditions
and humans are now paying the price.
1. Improving broiler transport. Roslin Institute and
Silsoe research institute. 2000.
2. Foul Deeds by Sustain, 1999.
3. Earthsave. What about chicken? April 2000.
4. CIWF. March 2000. (Danbury, T, C et al. Self- Selection
of the analgesic drug carprofen by lame broiler chickens.
5. Welfare of broilers. CIWF. Nov. 2000.
6. Kestin, S,C et al. Relationships in broiler chickens
between lameness, liveweight, growth rate and age. February
7. Poultry Litter Management. MAFF. 1997.
8. Heat Stress in Poultry. MAFF. 1995.
Fears for the Chicken Industry. IC Wales. May 2006.
10. Shes a lot smarter than you think. The Daily
11. Behind closed doors. RSPCA. 2002.
12. Sentenced to Death. Rebecca Smith. Viva! 2000.
13. Richard Young and Alison Craig.The truth about drugs
and poultry. The Soil Association. 2002
14. The Observer. The Cluck Stops Here. March 2002.