Hens & Eggs
The laying hen
Hen eggs are a reproductive body laid by the female that consist of an
ovum surrounded by nutrient material, layers of membrane and a protective outer
shell.
Today’s egg laying hens are descended from the Red Jungle fowl (Gallus gallus) of Asia
which lays around 60 eggs a year. Modern
breeds of domestic hen have been selectively bred to lay over 300 eggs a year.1
Selective breeding for high egg production has resulted in distinct
strains of birds for egg laying and for meat production. Birds of the laying strain do not make good
meat birds and as a result male birds of the laying strain, who neither lay
eggs nor produce meat efficiently, are killed when a day old.
Female hens in egg farms suffer from a range of welfare problems and
restrictions during their lifetime. When
the productivity of the flock falls the hens are sent for slaughter and are
quickly replaced with more profitable animals. Laying hens are normally only kept for one
year before they are slaughtered - their natural lifespan is around seven
years. This slaughter of “spent” hens takes
place even in free range systems.
The egg industry
Farming
systems for egg-laying hens
Battery Cages
In the UK nearly 17 million laying hens
are kept in battery cages which are so small that they cannot stretch their
wings, peck, scratch the ground, or perform other natural behaviours such as
dust bathing, perching and laying their eggs in a nest.3
Battery cages provide a floor space of 550cm² per hen
of cage area,4 equivalent to a piece of A4 paper. A battery cage typically contains four or five
hens. The cage floors are sloped up to 21.3% (or 12
degrees) depending on the floor type which may consist of wire mesh.4 The slope is so that the eggs roll
forward for collection by the farmer and puts painful pressure on the hen’s toes, causing damage
to the bird’s feet.5
Hens
housed in battery cages are susceptible to feather pecking (whereby the hens
will attack and peck each other) which occurs in situations of social and
physical stress.6 Feather pecking has also been described as
redirected ground pecking as caged hens are unable to ground peck.7 Feather pecking leads to feather loss and
hens may cannibalise birds with exposed flesh. In an effort to prevent feather
pecking farmers debeak the birds (see debeaking).
The
lack of exercise and high egg production can lead to brittle bones that are
easily broken. The Institute of Food Research in Bristol found nearly 30% of caged birds had
broken bones by the time they reached the water bath stunner in the
slaughterhouse.8
Battery
systems are to be outlawed in Europe from
2012, but the so-called ‘enriched cages’ that will replace them are little
better.
“Enriched”
Cages
Enriched cages must provide at least
750 cm2 per hen, of which 600 cm2 should be “useable
area”9, the remaining area being shared space for items such as a
nest box. Enriched cages should have litter,
a claw-shortening device and a perch.4 The extra space in enriched cages is equivalent to roughly a
postcard-sized piece of paper when compared to a battery cage and the facilities provided still
deprive the birds of the ability to fulfil their natural behaviours.9
Birds in enriched cages have slightly
better bone health compared to hens kept in battery cages but their bones are
still classed as osteoporotic.10 Birds in enriched cages are still
vulnerable to feather pecking behaviour and are therefore debeaked (see
debeaking).
Barn
Systems
“Barn” eggs are produced from hens kept
in flocks confined to a shed with no access to the outdoors. Hens may be stocked at a density of 12 hens
per square metre.11 Litter
should be provided for scratching and dust bathing but only needs to cover one
third of the ground surface.12 Nest boxes should be provided at 1 nest box
for every 7 hens or a communal nest for every 120 hens.12 Perches should also be provided allowing 15cm
of perch per hen.12 Hens in
Barn systems are debeaked in an attempt to control feather pecking
behaviour.
“Free”
Range
Birds
in free range systems can be stocked at a density of 9 hens per square metre.12 In addition the hens must have continuous
daytime access to open runs that should mainly be covered with vegetation and
at a maximum stocking density of 2,500 birds per hectare which equates to 4
square metres per hen.12 Birds in free range systems may be debeaked
to combat feather pecking.
Debeaking
Hens’
beaks have an extensive nerve supply13 but to combat feather pecking
famers debeak them. During debeaking or
“beak trimming” a red-hot blade sears off the end of the birds’ beak. Debeaking occurs in caged, barn and free
range systems. Debeaking is a serious
mutilation which results in a significant reduction in preening and pecking
afterwards.14 This reluctance
to use the area after amputation is thought to be guarding behaviour in
response to pain and discomfort. As
feather pecking occurs among stressed birds unable to fulfil their natural behaviours
debeaking adds insult to injury by punishing the birds for the systems they are
kept in.
Malignant Tumours
Another welfare problem associated with
selectively breeding hens to lay more 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”.15
Slaughter of Spent Hens
Most egg-laying hens in the UK are sent for slaughter after a
year of egg production.3 The
hens are caught and bundled into crates before being transported by lorry to
the slaughterhouse. One study found that
at the time of catching and crating, levels of the stress hormone
corticosterone in battery hens were 10 times higher than normal.16 Around 30% of battery hens arriving at the
slaughterhouse are reported to have at least one
freshly-broken bone.17 The
number of freshly broken bones in live birds prior to slaughter and the number
of old healed breaks had been described as “unacceptably high”.18
“Spent” hens are considered to be of low value and after slaughter their
flesh will be used in chicken soups, pastes, pies, pet food, etc.
Slaughter
of Cock Chicks
For every hen hatched for egg
laying there is a cock chick that is killed because he is the wrong strain to
be raised for meat. Common slaughter methods
include gassing, neck dislocation and the ‘macerator’, a device that shreds
chicks alive. Over 40 million day old
chicks are killed in hatcheries in Britain every year.19
Food vs. Feed
Hens
laying eggs don’t produce food, they wasteit! It takes approximately 1.8
kilograms (4 pounds) of grain to produce just 12 eggs.20 This is because the conversion of crops by
farm animals into food for humans is grossly inefficient.
Environmental Impact
Ammonia
is a common by-product of animal waste.
Ammonia gas escaping into the atmosphere is a serious pollutant linked
to acid rain. As part of its Integrated
Pollution Prevention and Control strategy Defra (the Department for
Environment, Food and Rural Affairs) states that egg production units “affect the environment by the production of
ammonia, dust, odour, noise etc and through emissions of nutrients and metals
associated with manure, used litter and dirty water. The effect of these could include
acidification, eutrophication, damage to ecosystems and build up of substances
in soil and reduction of amenity.”21
Human Health
Eggs
are a source of salmonella food poisoning.
Advice from the Government’s Food Standards Agency (FSA) warns that “some eggs contain salmonella bacteria,
which can cause serious illness, especially among elderly people, babies,
toddlers, pregnant women and people who are already unwell.”22
Go Egg Free
You
don’t need to eat eggs to have a healthy balanced diet. It's very easy to make egg-free cakes,
quiches, mousses and other traditionally “eggy” dishes. Most vegan cookbooks
contain plenty of such recipes or have a look at our cooking without eggs, cakes and desserts pages.
1 Compassion in World Farming (CIWF). Alternatives to the
Barren Battery Cage for the Housing of Laying
Hens in the European Union. Godalming, Surrey:
CIWF; 2007
2
British Egg Information Service (BEIS). Knowledge Guide: Egg facts and figures.
London: BEIS;
2009 http://egginfo.co.uk/page/eggfacts (accessed 16 October 2009)
3
CIWF. Practical Alternatives to Battery Cages.
Godalming, Surrey: CIWF; 2004
4 Defra. The Welfare of Farmed Animals (England)
Regulations 2007. London: Defra; 2007
5
Appleby MC. Do Hens Suffer in Battery
Cages? A Review of the Scientific
Evidence. Institute
of Ecology and Resource Management, University of Edinburgh; 1991
6 The Merck Veterinary Manual. Chickens: Behavioural
Problems. Merck, New Jersey;
2005
7
Blokhuis HJ. & Wiepkema PR. Studies of Feather Pecking in Poultry. The
Veterinary Quarterly 1998; 20(1): 6-9
8
Kilpatrick D. & McCoy M. et al. Density and breaking strength of bones of
mortalities among caged layers. Research in Veterinary Science 1996;
60(2): 185-186
9 CIWF Laid Bare; The Case Against Enriched Cages in Europe. Godalming, Surrey:
CIWF; 2004
10
Appleby MC. & Hughes BO. et al. Comparison
of bone volume and strength as measures of skeletal integrity in caged laying
hens with access to perches. Research in Veterinary Science. 1993; 54(2):
202-206
11
Defra. Eggs and poultry: frequently asked questions. Defra; 2007 http://www.defra.gov.uk/foodrin/poultry/faq/marketing.htm#freerang
(accessed 26 January 2009).
12 Defra. Laying Hens; Code of Recommendations for the Welfare Livestock. London: Defra; 2002
13 Gentle MJ. Cutaneous
sensory afferents recorded from the nervus intramandibularis of Gallus gallus var. domesticus. Journal of Comparative Physiology 1989; 164(6):
763-774
14 Gentle MJ. & Hunter
LN. et al. The onset of pain related behaviours
following partial beak amputation in the chicken. Neuroscience Letters 1991; 128(1): 113-116
15 Anjum
AD. & Appleby EC. et al. Oviduct Magnum Tumours in the Domestic Fowl and
their Association with Laying.
Veterinary Record 1989; 125(2): 42-43
16 Broom DM. & Knowles
TG. Effect of catching method on the concentration of plasma corticosterone in
end-of-lay battery hens. The Veterinary
Record 1993; 133(21): 527-528
17
Gregory NG. & Wilkins LJ. Broken
bones in domestic fowl: handling and processing damage in end-of-lay battery
hens. British Poultry Science 1989; 30(3): 555-562.
18
Knowles TG. & Wilkins LJ. The problem of broken bones during the handling
of laying hens – a review. Poultry Science 1998; 77(12): 1798-1802
19
Humane Slaughter Association (HSA). Gas killing of chicks in hatcheries.
Wheathampstead, Hertfordshire: HSA; 2006 http://www.hsa.org.uk/Resources/Publications/Technical%20Notes/TN14.pdf
(accessed 27 January 2009)
20
United States Department of Agriculture (USDA). An analysis of the effect of an
expansion in biofuel demand on U.S.
agriculture. Washington, USA:
USDA; 2007
21
Defra. Integrated pollution, prevention and control (IPPC) for a laying hen
installation. London:
Defra; 2006 http://www.defra.gov.uk/environment/ppc/envagency/pubs/pdf/henlaying.pdf
(accessed 26 January 2009)
22
Foods Standards Agency (FSA). Eggs. FSA; 2002
http://www.food.gov.uk/safereating/microbiology/eggs2002advice
(accessed 27 January 2009)