"The emotion-laden word 'mutilation' is sometimes used in
describing husbandry practices such as removing a portion of a
hen's beak ... [However] removal of certain bodily structures,
although causing temporary pain to individuals, can be of much
benefit to the welfare of the group."
James V. Craig, Domestic Animal Behavior.
1981, pp.243-44
American poultry and egg producers using battery cages and
crowded floor systems remove one-half to two-thirds of the birds'
beaks to reduce "cannibalistic" pecking. Cannibalism is a
distorted behavior pattern in domestic fowl and game birds reared
in captivity resulting from the abnormal restriction of the
normal span of activities of a healthy, secure, ranging fowl. It
includes vent picking, feather pulling, toe picking, and head
picking. Diseases of Poultry, 8th ed. States that "A different
form of cannibalism is now being observed in beak-trimmed birds
kept in cages. The area about the eyes is black and blue with
subcutaneous hemorrhage, wattles are dark and swollen with
extravasated blood, and ear lobes are black and necrotic." p.741.
Mason & Singer, Animal Factories, 1990, p. 39, note de-beaking started around 1940 when a San Diego poultry farmer found
if he burned off the upper beaks of his chickens with a
blowtorch, they were unable to pick and pull at each other's
feathers. His neighbor adopted the idea but used a modified
soldering iron instead. A few years later a local company began
to manufacture the "Debeaker," a machine that sliced off the ends
of birds' beaks with a hot blade. Broiler chicks are debeaked
once because they're slaughtered before their beaks can grow
back. [Some broiler producers no longer debeak, relying instead
on youth, lethargy, and dim lighting to control behavior.] Laying
hens and breeding flocks are debeaked, sometimes twice, during
the first week of age and sometimes again between 12 and 20 weeks
of age. It is recommended that turkey poults be debeaked between
two and five weeks of age. Ducklings and goslings are debilled by
slicing off the forward edge of the upper bill with an electric
debeaking machine. An operator debeaks 12 to 15 birds a minute.
Lyon Electric Co., of Chula Vista, CA, touts its 6-10 day
old precision beak trimming method as the most popular type used
today to trim breeder and layer chicks, noting "Failure to beak
trim properly can damage bird livability and uniformity. It can
cause starve outs, feed wastage and even the cannibalism it was
to prevent. This adds up to lost profits."
"If an electric beak trimmer is not available, a temporary
form of trimming can be done by using a sharp jackknife."
Diseases of Poultry, 8th ed, p. 743.
Some poultry scientists and other poultry industry
representatives say opposition to debeaking is based "more on
emotion than research." In fact, debeaking was fully explored by
the Brambell Committee, a group of veterinarians and other
experts appointed by Parliament to investigate animal welfare
concerns arising from intensive farming in the early 1960's. The
committee wrote in 1965: "There is no physiological basis for the
assertion that the operation is similar to the clipping of human
finger nails. Between the horn and bone [of the beak] is a thin
layer of highly sensitive soft tissue, resembling the quick of
the human nail. The hot knife blade used in debeaking cuts
through this complex horn, bone and sensitive tissue causing
severe pain."
In 1990, in "Behavioral evidence for persistent pain
following partial beak amputation in chickens," published in
Applied Animal Behavior Science, Vol. 27, Michael Gentle and his
associates at the Institute of Animal Physiology and Genetics
Research, Edinburgh, Scotland, showed that experimentally
debeaked chickens demonstrated chronic pain and suffering
following the operation. Gentle explains: "The avian beak is a
complex sensory organ which not only serves to grasp and
manipulate food particles prior to ingestion, but is also used to
manipulate non-food articles in nesting behavior and exploration,
drinking, preening, and as a weapon in defensive and aggressive
encounters. To enable the animal to perform this wide range of
activities, the beak of the chicken has an extensive nerve supply
with numerous mechanoreceptors, thermoreceptors, and nociceptors
[ nerve endings sensitive to mechanical pressures, heat and
pain]....Beak amputation results in extensive neuromas [tumors]
being formed in the healed stump of the beak which give rise to
abnormal spontaneous neural activity in the trigeminal
[threefold] nerve. The nociceptors present in the beak of the
chicken have similar properties to those found in mammalian skin
and the neural activity arising from the trigeminal neuromas is
similar to that reported in the rat, mouse, cat and the baboon.
Therefore, in terms of the peripheral neural activity, partial
beak amputation is likely to be a painful procedure leading not
only to phantom and stump pain, but also to other characteristics
of the hyperpathic syndrome, such as allodynia and hyperalgesia
[the stress resulting from, and extreme sensitiveness to, painful
stimuli]."
Gentle and associates compared 5 behaviors in 16
experimentally debeaked Leghorn hens with the same behaviors in a
control (nondebeaked) group of hens: number of bill wipes, head
shakes, drinking movements, pecks directed to water and floor,
and pecks directed to cage sides. In their experiment, "Partial
beak amputation produced a number of significant alterations to
the behavior of the birds. The birds pecked less at the
environment after amputation than before and this difference can
be interpreted as guarding behavior of a painful area of the
body, similar to that seen in man and other animals....Guarding
behavior can also be used to explain the reduction in head
shaking and beak wiping following amputation. Head shaking is a
behavior commonly associated with feeding and drinking and, like
beak wiping, it functions to remove food particles or irritant
substances from the mouth or surface of the beak....The
modifications in the pecking and drinking behavior of birds
following partial beak amputation [conforms with other reports]
that partial beak amputation results in long-term (56 weeks)
increases in dozing and general inactivity, behaviors associated
with long-term chronic pain and depression."
Further Reading
Breward, J. (1984) "Cutaneous nociceptor [ pain receptors]
in the chicken beak." Journal of Physiology, London, 346: 56P.
Duncan, Ian et al. (1989) "Behavioral consequences of
partial beak amputation (Beak Trimming) in poultry." British
Poultry Science, 30: 479-488. The authors conclude that "the
behavioral data presented here together with the recent neural
data (Breward and Gental, 1985), suggest that the idea of beak
trimming being a short-lived discomfort for the bird, may be far
from accurate. The short and long-term changes in behavior,
particularly the substantial decrease in activities involving the
beak and the increase in inactivity particularly in the first
week after the operation, suggests that the birds are suffering
severe pain."
Appleby, Michael C. (1991) Do Hens Suffer in Battery Cages?
A Review of the Scientific Evidence Commissioned by the Ahtene
Trust. Institute of Ecology and Resource Management, the
University of Edinburgh. 20 pp. On debeaking, see pp. 9-10: "The
main injury caused by humans, knowingly rather than accidentally,
is beak trimming. It is now known to cause pain, in the short
term and probably also in the long term, in a way similar to
other amputations."
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