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There are laws in the UK and Europe safeguarding the welfare of animals immediately before and during slaughter in abattoirs (for food) and knacker’s yards (disposal of animals unfit for food). These laws were extended in 1995 to include slaughter in other places (e.g. on-farm) and for other reasons (e.g. disease control).
It is a fundamental requirement that animals must not be subjected to avoidable excitement, pain or suffering before or during slaughter.
Other than in specific circumstances (e.g. religious slaughter), animals must be stunned before slaughter so that they are unconscious and cannot feel pain. ‘Stunning’ is defined as “any process which causes immediate loss of consciousness which lasts until death.”
Slaughter comprises stunning, which causes unconsciousness, followed by cutting major blood vessels resulting in death as a result of rapid loss of blood.
It is an absolute offence to cause or permit an animal avoidable excitement, pain or suffering. There are also specific rules on handling, stunning, slaughter or killing of animals.

The EU has adopted detailed welfare at slaughter rules. These are set down in Directive 93/119/EC on the protection of animals at the time of slaughter or killing. They are implemented in Great Britain by the Welfare of Animals (Slaughter or Killing) Regulations 1995, as amended, and in Northern Ireland by the Welfare of Animals (Slaughter or Killing) Regulations (Northern Ireland) 1996.

The Regulations cover farm animals and poultry, rabbits, horses, hatchery waste and animals farmed for their fur*.

They exclude animals killed during a sporting event, wild game, and “any act lawfully done under the Animals (Scientific Procedures) Act 1986 (a)”.

*NB: The farming of animals for their fur was banned in the UK in 2000; fur farmers are to be allowed around 2 years from that date in which to close down their farms. The production of rabbit fur is still allowed, since meat is the main product on rabbit farms, the fur being a by-product.

Key Terms Explained

In the context of this legislation, “slaughter” means the bringing about of death by means of stunning and subsequent bleeding. According to the legislation, a state of unconsciousness must persist, following stunning, until death supervenes through blood loss. Alternatively, the stun/kill method may be used, when the electrical current alone is strong enough to cause cardiac arrest.

“Religious methods of slaughter” are legal in the UK, and omit the requirement to stun animals prior to bleeding to death. These methods represent a minor sector of UK slaughter, and prior stunning of poultry is becoming increasingly acceptable by religious bodies.

“Killing” usually implies causing death instantaneously (by shooting) and generally involves emergency measures.

“Slaughterhouse” means a place where death is caused to animals/birds on a commercial basis, for human consumption.

“Knackers’ yard” means a place where death is caused to animals/birds on a commercial basis, but not for human consumption.

“Commercial” means in the course or furtherance of a business or for reward, or in a market place.

In this legislation, the term “animal” includes “birds” unless the context indicates otherwise. The 1995 Regulations apply to:

Animals killed in slaughterhouses or knackers’ yards by the “stun/kill” method or by captive bolt.

Animals killed instantaneously, by means of a bullet.

Pigs and birds whose death results from exposure to gas mixtures.

Surplus chicks and embryos destroyed as “hatchery waste”.

Animals killed by religious methods.

Slaughter for Disease Control

Where the purpose of killing an animal or bird is disease control the following methods of bringing about death are legal:

Free bullet
A lethal concentration of gas
Dislocation of the neck (for rabbits and birds)
Captive bolt
Anaesthesia (administered before any other procedure is followed).

Requirement to Safeguard Animals in Slaughterhouses or Knackers’ Yards

A person competent to act in accordance with the Regulations must be present at all times that live animals are on the premises.

Animal Welfare Legislation and Codes

Anyone involved in activities governed by the Regulations must:

Be acquainted with the contents of the Regulations and Codes relevant to his/her activities.
Have access to relevant welfare codes.
Have received “instruction and guidance” on the requirements of relevant legislation and codes.
Have the necessary licence.

NB: Codes of Practice issued in booklet form by MAFF are intended to give guidance and recommendations to farmers. They do not in themselves render anyone who may act against the recommendations contained in them liable to legal proceedings. However, in the event of a contravention of the Regulations, failure to follow the guidance contained in a Code of Practice may be relied on by the prosecution as tending to establish guilt.

The Licensing of Slaughtermen


An animal must be killed immediately, for emergency reasons.

The person killing the animal is its owner and is killing it for his or her own private consumption.

The animal is not killed for a commercial purpose.

The animal is killed in a field by means of a free bullet.

A bird is killed by decapitation or neck dislocation on premises where the bird was reared.

An animal is killed as part of disease control in accordance with provisions contained in Schedule 9.

Any fox or mink is killed in accordance with provisions contained in Schedule 10.

Surplus chicks or embryos in hatchery waste are destroyed in accordance with Schedule 11.

An operator uses equipment to stun, slaughter or kill any animal without being responsible for the basic operations connected with slaughter, for example, when:

A worker shackles birds.

The person is a veterinary surgeon or is acting under the direction of a vet.


Restraining an animal prior to stunning or killing it.

Stunning an animal.

Slaughtering/killing an animal.

Assessing the effectiveness of stunning or killing an animal.

Shackling or hoisting a stunned animal.

Bleeding an animal which is still alive.

The Issuing of Certificates of Competence

A certificate of competence is issued by veterinary surgeons authorised by the Minister of Agriculture who has assessed the competence of the applicant, regards him or her as a fit and proper person to hold the certificate and has checked that he or she is not below the age of 18.

Applicants wishing to slaughter animals by the Jewish method have licences granted by the Rabbinical commission in England and Wales, and by the chief Rabbi in Scotland.

The Span of a Licence

Licences, once granted by the Minister, may remain valid until revoked or suspended by the Minister.

Provisional Licences

An authorised veterinary surgeon may issue a provisional licence for a period not exceeding three months, on condition that operations are carried out in the presence of a veterinary surgeon or the holder of a registered licence. Provisional licences may be renewed at the discretion of an authorised veterinary surgeon.

The Refusal or Revoking of Licences

Failure to comply with any conditions of the licence, or the conviction of an offence under any law concerning the welfare of animals may deny the holder, or would-be holder, a licence.

Pre-Slaughter Rules

On arrival at a slaughterhouse or knackers’ yard animals must be:

unloaded as soon as possible, or, if this is not possible, they must be protected from adverse weather conditions and provided with adequate ventilation.

the above must apply once the animals have been unloaded.

any animals already subjected to high temperatures must be cooled by appropriate means.

animals who may injure each other, for whatever reason (sex, species, age or origin) must be lairaged apart.

sick or disabled animals must be kept apart from fit animals prior to slaughter.

no person may drag a stunned animal over an unstunned animal.

Inspection of Animals Awaiting Slaughter

The occupier of a slaughterhouse or knacker’s yard, or the competent person acting on his/her behalf must ensure that the “condition and state of health” of every animal is inspected at least every morning and evening.

Any animal found to have experienced pain or suffering during transport or following arrival at the slaughterhouse or knacker’s yard, or which is too young to take solid feed, must be slaughtered immediately.

Any animal found unable to walk to the place of slaughter may not be dragged there, but either be killed where it lies, or (providing this doesn’t cause pain) transported on a trolley to the place of slaughter.

Additional Requirements for Pre-Slaughter Animals

Care must be taken not to frighten, excite or mistreat animals.
No animal may be overturned.
Any animal not slaughtered immediately on arrival must be lairaged.
No animal may be taken to the place of slaughter unless it is to be slaughtered straight away.

Instruments to Make Animals Move

Electric prods may only be used on adult bovine animals and adult pigs which refuse to move. Shocks may last no more than two seconds and be “adequately spaced out”. The animal receiving the shocks must have room ahead of it in which to move. Such shocks may only be applied to the muscles of the hindquarters.

General Treatment of Animals

No person shall strike or apply pressure to any particularly sensitive part of the body of an animal, nor twist or break the tail, or grasp the eye(s) of any animal.

No person shall hit or kick any animal.

Lairaging of Animals

Lairaged animals must:

have an adequate supply of bedding overnight, unless the flooring is slatted or is a mesh floor.
have drinking water available at all times.
be given a sufficient amount of wholesome food on arrival at the lairage and twice daily thereafter (except for 12 hours before slaughter).
be provided with food so feeding can take place without undue disturbance.
be able to lie down, turn around and stand up without difficulty (unless tethered).
if tethered, be able to lie down and stand up without difficulty.

Handling of Animals Delivered in Containers

Containers of animals/poultry must not be thrown, dropped or knocked over.
Where possible, containers should be loaded horizontally and mechanically (as with modules).
Care must be taken not to injure animals in containers with perforated or flexible bottoms (as with poultry crates and some modules).
Where appropriate, animals should be unloaded individually.


In this Schedule (5), “animal” means any soliped, ruminant, pig, rabbit, or bird.

Permitted Methods of Stunning

captive bolt

NB: The legal requirements for gas stunning are set out in a separate section (Schedule 7, parts 1-3 in 1995 Regulations) and applies only to pigs and birds.

In the case of (a) the instrument must be positioned and applied so as to ensure the projectile enters the cerebral cortex and the correct strength of cartridge or other propellant must be used to ensure an effective stun.

No person may shoot any bovine animal in the back of the head. This applies to sheep too, except in the case of obstruction by horns. In such a case, the shot must be placed immediately behind the base of the horns and aimed towards the mouth and bleeding must be commenced within 15 seconds of shooting or the sheep or goat killed within 15 seconds of shooting.

The captive bolt must be retracted to its full extent after each shot, and not used until repaired if this proves impossible.

Rabbits an exception

Rabbits my be stunned using a non-mechanical blow providing that the operation is carried out in such a way that the animal is rendered unconscious, and remains so, until dead.

Stunning by electronarcosis – electrodes

The electrodes must be so placed that they span the brain, allowing the current to pass through it.

Measures must be taken to ensure good electrical contact.

The strength and duration of the current must ensure the animal is immediately rendered unconscious and remains so until dead.

Checking the Viability of Apparatus

Apparatus must:

measure the impedance of the load.
fail to operate unless the current delivered ensures unconsciousness until death.
include a device to display the voltage and current under the load; this device must be clearly visible to the operator.

Pithing Banned Throughout the EU

Pithing is a post-stunning operation sometimes carried out on cattle, and less often on sheep and goats. The procedure is designed to cause destruction of brain tissue after stunning, to ensure the irreversible loss of consciousness.

A steel rod is driven into the brain, causing damage to central nervous tissue. Until December 2000 pithing was legal, but following a new EU Commission decision (2000/418/EC) on specified risk material (SRM), pithing is banned (from January 1st 2001). The ban is intended to protect slaughterhouse workers and consumers from the danger of BSE/new variant CJD. The fear is that neural contamination of the animals’ blood may result from pithing, so spreading possible infection throughout the carcase and beyond.

The UK Food Standards Agency states: “…pithing is not necessary for either purpose [i.e. preventing the regaining of consciousness or involuntary kicking from stunned animals – Ed.], provided effective stunning is carried out and abattoirs have arrangements which ensure the efficient shackling, hoisting and sticking of cattle.”1

NB: Effective stunning should be followed quickly by bleeding to avoid the possibility of unpithed animals recovering consciousness.


Shackle Lines

The legislation requires that shackle lines are designed and positioned to ensure that:

Suspended birds are kept clear of obstructions.
Disturbance is kept to a minimum
The entire shackle line, up to the waterbath entrance, is accessible, so staff can reach any bird in need of attention.
Any processing equipment used for live birds is readily available, and able to be used if needed.
No bird is suspended in such a manner as to cause it avoidable pain or suffering.

The MAFF Code Welfare of Poultry at Slaughter illustrates two designs considered to be satisfactory. A third design, in which the slot narrows to a point, is described as “unacceptable”. The Code states: “Shackles with parallel slots and bases at right angles to the body of the shackle in which birds’ feet rest appear to be the most comfortable.”

Hanging On Time for Poultry

Turkeys must not be suspended for more than 6 minutes. Other birds must not be suspended for more than 3 minutes.

NB: The UK Government is presently considering further amendments to the current (1995) slaughter law. Following consultation, and depending on decisions by Ministers, the maximum permitted hanging on time may be reduced. This is because research indicates that birds may experience pain when shackled. Data collected by the Meat Hygiene Service indicates that in many poultry plants birds are already suspended for less than the current legal limit; clearly, this is to the birds’ advantage.

The Shackling of Birds of Exceptional Weight

Catering size chickens and turkeys, and ‘spent’ breeders are much heavier than the majority of birds slaughtered. For example, a male breeding turkey can weigh as much as an eight to nine year-old child, and such birds suffer greatly if hung in shackles. Conversely, under-sized birds present welfare problems if hung in shackles. UK legislation does in theory protect birds of exceptional weight/size. Having stated that birds, unlike other species, may be suspended before they are stunned, there comes the following stipulation: “…provided that…no bird is suspended in such a manner as to cause it avoidable pain or suffering.”

But the Slaughter Code elaborates thus: “On removal from the crate or module, birds should be checked to ensure that they are not suffering from any condition which may reasonably be supposed to be causing them unnecessary pain or distress. The law requires that any bird in such a condition must be immediately slaughtered. In some cases, it may be appropriate to hang such birds on the slaughter line, but it is an offence to do so where the action of shackling in itself would cause further unnecessary suffering (e.g. if the bird has a broken leg). The following points should be particularly noted:

birds not suitable for shackling and suspension before stunning, if this would cause unnecessary pain or distress, would include very heavy turkeys and geese or birds with joint deformities
runts should not be hung live on the shackle line mixed with other birds because, being undersize, their heads may miss the stunner.”

There is scientific evidence to show that large numbers of intensively reared poultry (especially the males of the species) suffer from painful hip and leg joint diseases and deformities2,3,4.

Stunning and Slaughter – Regulations to be Tightened

The UK Government is currently considering amendments to the 1995 slaughter Regulations. At present, there is no specification as to the electrical current required. An amendment to the existing law may well specify the strength of the electrical current, and this will in all likelihood set the figure much higher than in the existing Slaughter Code, which puts the minimum mA per bird at 105 (alternating current). This change will come about because of recent research indicating that birds may regain consciousness, or indeed fail to be rendered unconsciousness, at 105mA. Furthermore, research indicates that different species of poultry demand different treatment at slaughter.

Another amendment may include a requirement to cut both carotid arteries, as a means of ensuring that the time for bleed out is shortened (further reducing the risk that animals may regain consciousness before death supervenes).

Changes and improvements regarding requirements for gas stunning of pigs and poultry are also under review.

Religious Slaughter

Methods required to satisfy religious traditions of members of the Jewish and Muslim communities

Bovine animals slaughtered by a religious method in a slaughterhouse may only be restrained in a pen, which remains in an upright position and has been approved by the Minister. This effectively prohibits the Weinberg Pen, whereby the unfortunate bovine animal was rotated upside-down before having its throat whilst fully conscious. This method was described the UK RSPCA as “very stressful and causing the animal to experience considerable terror”6.

Such pens must contain an effective head restraint and means of support to take the weight of the animal at slaughter and be of a design to avoid pain, suffering, agitation or injury.

No bovine animals may be placed in a restraining pen unless the person who is to carry out the slaughter is ready to make the incision.

No animal may be shackled or hoisted unless it is unconscious.

Animals small enough to be restrained manually (sheep, goats, calves) in a cradle or on a table may only be placed therein or thereon one at a time.

A captive bolt instrument must be kept nearby for use in cases where an animal may be seen to be subjected to avoidable pain and suffering, may be agitated or be injured.

When animals have not been pre-stunned a) the knife must be inspected before each incision to check it is sufficiently sharp, and b) the slaughter must ensure that severence is carried out “by rapid uninterrupted movements of a knife” so that both carotid arteries and both jugular veins are severed.

Animals killed by the above method must not be moved until they are unconscious, and in any event, not before the expiry of a) not less than 20 seconds for sheep and goats, and b) not less than 30 seconds for any bovine animal.

Slaughter Prohibited Outside a Slaughterhouse

Since the 1999 Amendment to the UK Slaughter Regulations (1999 No. 400), it is illegal to slaughter any animal by a religious method, or cause or permit it to be so slaughtered, other than in a slaughterhouse licensed under regulation 4 of the Fresh Meat (Hygiene and Inspection) Regulations 1995 (d).

Day Old Chicks and Hatchery ‘Waste’

At the time of writing, poultry hatch out evenly – roughly 50% of each sex. There are moves afoot to make it possible to select the sex of chicks of the laying strain, to avoid the ‘need’ to destroy ‘surplus’ males. It is customary to kill all male laying-type chicks and any deformed or diseased day-olds of any type of bird, either by gassing or by maceration.

The only approved methods, laid down in the 1995 Regulations, are:

use of a mechanical apparatus producing immediate death
exposure to gas mixtures
dislocation of the neck.

For method a) it is required that the apparatus contains rapidly rotating blades or projections which ensure immediate death.

For method b), there are three allowable gas mixtures:

a source of 100% carbon dioxide,
a maximum of 2% oxygen by volume and 90% argon (or other inert gas) by volume in atmospheric air,
25-30% carbon dioxide by volume and 60% argon (or other inert gas) by volume in atmospheric air.

When the UK Government updates the 1995 Regulations it is likely that carbon dioxide will no longer be recommended. Carbon dioxide has been found to be deeply aversive to animals, causing unpleasant sensations of breathlessness4.

Method c) must ensure that the dislocation is accompanied by severance of the spinal cord and blood vessels in the chick’s neck.

Embryos in Hatchery Waste

Any embryo in hatchery waste must be killed by a mechanical apparatus ensuring immediate death.

Gas Stunning for Poultry & Pigs

One of the greatest welfare benefits of gas stunning for poultry is that birds need not be removed from the crates or modules in which they have arrived at the place of slaughter, or be hung in shackles while alive.

In the present 1995 UK legislation “gas mixture” means either:
a maximum of 2% total oxygen by volume and 90% argon (or other inert gas) by volume in atmospheric air; or
15% to 30% carbon dioxide by volume and 60% argon (or other inert gas) by volume in atmospheric air.

UK proposals, still at consultation stage, include:

A higher percentage of argon in the mixture
A reduction in the amount of oxygen by volume in gas mixtures (down to no more that 1.5%) to ensure that all birds are dead on leaving the chamber.

Recent research by scientists from the UK’s Bristol University and Aristotle University, Thessaloniki, Greece, reviews the welfare problems associated with electrical and gas stunning/killing of poultry. In Table 2 “Major welfare concerns associated with the waterbath electrical stunning”, the following are noted:

The stress of removing conscious birds from containers and “tipping or dumping” live poultry onto conveyors.

The “inevitable” stress, pain and trauma associated with shackling.

The stress and pain of hanging upside down in shackles.

The pain of the pre-stun shocks which occur when birds flap unduly or when wings touch the waterbath before the heads.

The pain and distress of birds who miss the stunner and proceed conscious to the neck cutting stage.

The pain and distress associated with recovery of consciousness during bleeding (a result of inadequate stunning and/or inappropriate neck cutting).

An especial potential welfare problem exists with game birds, who attempt to fly while hanging upside down in shackles. This can lead to injury or suffering. A quail’s natural reaction to danger is to fly upwards, so these birds, which when farmed intensively are hung at slaughter in ‘mini-shackles’, doubtless suffer in a similar way.

Referring to Table 2, the scientists state: “Considering all the potential welfare problems associated with the commercial stunning of poultry in waterbaths, it is hardly surprising that both scientists and the industry are seeking alternative stunning/killing methods to improve matters. On the other hand, because of the complexity of the electrical stunning systems in multiple bird waterbaths, some argue that it is unlikely that humane stunning will ever be achieved in these systems under commercial conditions (Boyd, 1994).”

Clearly, increasing the strength of the electrical current is helpful if a stun/kill (i.e. a stun resulting in instant cardiac arrest) is achieved. However, the many other problems (missing the stun altogether, pre-stun shocks etc.) remain.

Correct Gas Stunning – the Humane Way Forward?

Leading UK animal welfarists contend that when gas stunning is used to kill poultry it is essential that the following factors are written into amended legislation:

The gas used should not be aversive (as is carbon dioxide)
The concentration of gas must be such that death is brought about solely by the effects of the gas mixture, and not by a combination of gas and bleeding out.
Poultry crates should be presented in a single layer, to avoid any danger of birds receiving differing concentrations of gas.
Appropriate action must be taken to check that poultry are dead on emerging from the chamber.

Gas Stunning of Pigs

At the time of writing, pigs may be killed by exposure to high concentrations of carbon dioxide (at least 70% carbon dioxide by volume in atmospheric air), so long as “each pig is exposed to the gas mixture for long enough to ensure that it is killed” (Schedule 7, part 11, 5(a)).

Work by Raj & Gregory shows that carbon dioxide is known to be an irritant, and research has found that pigs show profound aversion to a high concentration of carbon dioxide, since it leads to “severe respiratory distress”5. The UK Government is presently reviewing the use of this method of gassing and leading UK welfare organisations are pressing for the phasing out of carbon dioxide, which should be replaced by 90% argon, known to cause minimal distress. MAFF appears to favour the change to an inert gas such as argon, and may demand its use independently of EU-wide legislation, demonstrating yet another area in which the UK, along with Sweden, has been at the forefront in redressing the welfare insults inflicted on animals.

UK animal welfarists hold that, when legislation is amended, it is essential that pigs are a) left long enough in non-aversive gas to give the best possible chance that all pigs are killed and that b) stun-to-sticking time is as short as possible, to ensure that any pig not killed outright is in no danger of regaining consciousness before death supervenes through blood loss.

The 1995 legislation requires the following procedures to be followed (which would doubtless apply to other gas mixtures):

The design of the gas chamber should not cause injury.
It should not cause compression of the pigs’ chests.
It must enable all pigs to remain upright until unconscious.
Pigs must be able to see each other as they are conveyed to the chamber.
Each pig must be conveyed to the part of the chamber containing a maximum concentration of the gas mixture within a period of 30 seconds.

It is also necessary to ensure that:

Pigs can be visually monitored in the chamber.
The light level is high enough to allow pigs to see each other when being conveyed into, and when in, the chamber.
Apparatus is installed to maintain the required concentrations of gas.

A device is fitted to:

Measure the concentration of gas at the point of maximum exposure.
Continuously display the concentration by volume of carbon dioxide as a percentage of the gas mixture at the point of maximum concentration in the chamber.
Give clearly visible and audible warning signals if the concentration by volume of carbon dioxide falls below 70%.

In addition, provisions must be made to flush the chamber with atmospheric air with the minimum of delay and it must be possible to access any pig with the minimum of delay.

The Operation of the Chamber

The occupier of the slaughterhouse in which the chamber is used shall ensure that:

Each pig is exposed to the gas mixture for long enough to ensure that it is killed.
Any such chamber is properly maintained.
Every person engaged in the killing is properly instructed to carry out the procedures outlined above, which shall include any necessary evacuation of pigs from the chamber.

The final requirements state that no pig may enter the chamber if the displayed concentration of carbon dioxide in the gas mixture falls below 70%, and no pig may be passed through, or left in, the chamber in the event of any defect in the gas chamber.

In Summary

The slaughter of animals is clearly an area where the possibility of the infliction of fear and pain presents a range of the most serious welfare problems.

UK legislation (often in step with EU-wide law) attempts to indicate how the worst suffering may be avoided.

It is encouraging to note that the UK Government is presently engaged in consultation with animal welfarists and scientists with a view to tightening up legislation still further, and publishing codes of practice which will suggest higher standards at all stages of farm animals’ lives through to death.

It is crucial that detailed animal welfare legislation exists, the aim of which is to minimise suffering. However, only strict enforcement at all stages can ensure its success.


Consultation letter from Food Standards Agency, 31st October 2000.

Duff, S.R., et al., 1987. The Gross Morphology of Skeletal Disease in Adult Male Breeding Turkeys. Avian Pathology, 16: 631-651.

Gregory, NG & Austin, SD, 1992. Causes of Trauma in Broilers Arriving Dead at Poultry Processing Plants. Veterinary Record, 131: 501-503.

Hocking, PM, 1992. Leg Disorders in Male Breeding Turkeys. Turkeys, June 1992, pp 16.

Raj, A.B.M. & Gregory, N.G., 1996. Welfare implications of the gas stunning of pigs: Stress of induction of anaesthesia. Animal Welfare, 5: 71-78

RSPCA, 1985. The Slaughter of Food Animals. Royal Society for the Prevention of Cruelty to Animals. Horsham: West Sussex.


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