Vegetarians International Voice for Animals

PART SEVEN: Poultry slaughter

According to the MHS, there are 77 slaughterhouses licensed to kill chickens by mainstream methods and 50 licensed to kill turkeys (10). In 1998, 846 million birds were in the UK (a percentage of these were killed by religious methods) - so the daily kill at each plant is vast.

65 out of 77 plants stunning chickens and 34 out of 50 plants stunning turkeys use the electric waterbath. This amounts to 73.9% of plants.

1.1% of plants plant use gas stunning and very low throughput premises tend to use an electric hand-held stunner. 12.5% of plants do not pre-stun at all (see Viva!'s "Going for the Kill" report on religious slaughter).

Dislocation of the neck

UK slaughter legislation states that birds may be killed by decapitation or dislocation of the neck. These procedures do not require a licence provided that they are carried out on premises forming part of an agricultural holding on which the bird was reared. (5)

Decapitation is not widely practised but neck dislocation is the most widely used method of slaughter on small-scale enterprises. (57)

Gregory and Wotton expressed concern about the effectiveness of neck dislocation in poultry. They tried crushing and stretching the necks of poultry (method 2 works in a similar manner to manual neck dislocation) and concluded that, "neither method consistently produced concussion and it is uncertain whether they cause instantaneous unconsciousness." (58)

Researcher Roger McCamley says that, "There is certainly a potential for welfare problems to arise when small scale seasonal producers kill large birds by neck dislocation. Usually, no training will have been sought or received and because of the small number and infrequency of slaughtering, little expertise in slaughter will be obtained." (57)

Untrained staff should not be permitted to kill birds on farms by methods which are not guaranteed to cause immediate unconsciousness. Scientists are not able to guarantee that neck dislocation causes instantaneous unconsciousness and birds will suffer far more at the hands of untrained workers.

'Dead on Arrival'

The Meat Hygiene Service report that "Despite the high level of care and attention to the transportation of birds as recorded on the checklist, the average percentage of birds that died in transit was recorded nationally as 0.2% of the weekly throughput." (10) This translates into 1.7 million birds each year.

Why do birds die?

Gregory and Austin examined the reasons for birds being "dead on arrival" in a paper published in The Veterinary Record. Death rates at the plant investigated were 0.19% on the day they investigated - slightly lower than the current national average. (59)

The researchers concluded over half the birds had died from heart failure and say, "Presumably the physiological responses associated with the stress of catching, loading and transporting the birds had been too much for the cardiovascular system to cope with".

The second most common cause of mortality was found to be dislocation of the femur (thigh bone) at the hip joint. This was associated with profuse haemorrhage. It occurred mainly in larger birds and the researchers say that, "It is thought that catching and carrying large birds by one leg is conducive to dislocation of the hip, and that catching by two legs would help reduce this problem." However, they point out that catching by two legs would slow down the catching rate, meaning that more staff (and therefore more money for wages) would be needed.

They caution that the survey will not have revealed the full extent of birds arriving with hip dislocations because they only counted birds who actually died. Any who survived would have, "entered the processing plant in the normal way".

Other birds died from a crushed skull, a cause of death which occurred most frequently in transporters which used plastic drawers. The researchers deduce that, "insufficient care was taken to ensure that birds were crouching down when the drawers were being closed."

So, before birds even arrive at the slaughter plant, they will have to endure the stress of catching, transportation and loading - procedures so stressful that they can cause birds to have heart attacks. Careless handling means that birds' skulls can be crushed and that dislocated hips are commonplace. Viva! is concerned to note that Dead on Arrival rates for birds show no sign of falling.


The process of hanging live birds upside down prior to slaughter causes extreme stress and has led 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.

Chickens kept on modern factory farms have been bred to grow far faster than they would naturally and this places a huge strain on their undeveloped limbs, causing painful crippling. Broiler chickens' bones are unable to form properly and what should be hard, calcified bone is frequently nothing more than soft cartilage. As a consequence, their skeletons fail to grow properly and their legs bend or break under their rapidly ballooning weight (60). The Agriculture and Food Research Council have stated that up to four fifths of broiler chickens have broken bones and deformed feet and legs or other bone deformities (61).

Shackling is incredibly painful for turkeys because of their immense weight. They are bred to have as much meat on their breasts as possible. But no exceptions are made even for the hugely overweight male breeding birds who can top 27 kg (about 60 lbs) - as much as an eight or nine year old child. The strain on their hip joints - which are often diseased - is enormous and painful.

Professor John Webster says that, "...certain welfare abuses are intrinsic to the [slaughter] system. Suspending birds upside down on shackles must induce some degree of fear. More seriously, this procedure must seriously exacerbate the intensity of pain in chickens and especially the heavier turkeys with chronic leg disorders. The stunning process cannot guarantee 100% efficiency. Finally, the whole stressful procedure takes time." (34)

UK legislation says that turkeys can be shackled for up to six minutes and other birds for up to three minutes before slaughter (5). The idea behind slaughter welfare legislation is - supposedly - to ensure the humane treatment of animals. Viva! believes that the law legitimises horrific suffering for birds in the run up to slaughter. It is particularly barbaric to allow turkeys with chronic leg disorders to be hung upside down by their legs for a full six minutes.

The law also states that "appropriate measures" should be taken to ensure that shackled birds are "in a sufficiently relaxed state for stunning or killing to be carried out effectively and without undue delay." A bird must not be shackled, "in such a manner as to cause it avoidable pain or suffering." (5) The whole procedure clearly causes pain and suffering - but exactly which elements are avoidable is not made clear.

No licence is required for shackling poultry prior to slaughter. The procedure may therefore be undertaken by untrained individuals whose competence has not been officially assessed (16). Line speeds can carry up to 9,000 birds an hour (62) meaning that operators will have to shackle birds at high speed.

Any slaughter system which depends on poultry being shackled intrinsically causes suffering. Viva! is appalled that the vast majority of UK poultry abattoirs continue to depend on this outdated, cruel system.

Painful electric shocks

When entering the electric waterbath, a bird's wings may be hanging lower than the head, meaning that the bird will suffer a painful electric shock. This is a particular problem for turkeys. The Scientific Veterinary Committee of the EU say that, "The prevalence of pre-stun electric shock in turkeys is high (about 80%)." (17)

Poultry scientist A.B.M. Raj says that various methods have been tried in an attempt to reduce this welfare problem but that, "In spite of these developments, a considerable proportion (6%) of turkeys still receive prestun electric shocks." (63) 35 million turkeys are killed annually so the 6% figure means that 2.1 million turkeys are still receiving painful electric shocks each year.

Birds inhale water

Gregory & Whittington identify another problem. After conducting an experiment, they conclude that, "chickens can and do inhale water during electrical stunning in a waterbath. No remedy for this is available at the moment." (64) The scientists explain that, "some birds defecate during stunning and hence foul the water of waterbath stunners." So, at stunning, live birds inhale faeces when they are dipped into the electric waterbath. This is perceived as a particular problem from the meat hygiene perspective because the fluids can leak out of the lungs and cause contamination.

The Electric Waterbath

Inadequate stunning is a real problem within the poultry industry. Ducks and geese in particular are known to "swan neck" - raising their heads when entering the waterbath and so avoiding full immersion. The Scientific Veterinary Committee of the EU say that it is especially difficult to stun ducks and geese effectively. They say that, "Heads of ducks and geese are not always immersed in the waterbath due to their anatomical disposition." (17)

The Meat Hygiene Service admit that, "Due to the ability of the birds to move during entry to the stunner, there will always be a small proportion of birds which are not stunned due to failing to make contact with the water...". (10) These birds are supposed to be removed from the line and killed by a "back up" killer - usually by decapitation.

The birds are fully conscious while they are having their necks cut.

Birds will pass the back-up killer at a speed of up to 150 birds a minute (62), so he will only have about half a second to check each one. If birds get missed, they will continue on to the neck-cutter whilst still conscious.

Birds regain consciousness

The aim of modern waterbath systems is supposedly to induce a cardiac arrest in birds so that they die and have no chance of regaining consciousness. However, not all birds have a cardiac arrest and the RSPCA say that, "Many birds are improperly stunned and recover consciousness before slaughter." (65)

Broiler chickens have been shown to have their somatosensory evoked responses abolished (an indication of unconsciousness) for at least 52 seconds after stunning in an electric waterbath. Another study showed that "end of lay" hens recover consciousness after as little as 22 seconds (66). Almost 90% of turkeys who do not develop a ventricular fibrillation show some recovery of their somatosensory evoked responses within 60 seconds of stunning (67).

A research paper by N.G. Gregory states that the time between stunning and neck cutting in broiler chicken plants varies between 14 and 37 seconds (68).

Gregory says that birds retain their brain function during exsanguination for longer than mammals. He shows a graph which reveals that it around 1.5 minutes for chickens and ducks to lose brain responsiveness after a cardiac arrest; almost 3 minutes after both carotid arteries are severed and around 5 minutes after one jugular artery and one carotid artery is severed.

These results are disturbing even if you take the optimistic view that the electric waterbath stuns birds for 60 seconds. Chickens will regain consciousness before they lose brain responsiveness if they do not have a cardiac arrest when they enter the waterbath.

"End of lay" hens only lose consciousness for 22 seconds and so Viva! is convinced that hens regain consciousness before they lose brain responsiveness if they do not suffer a cardiac arrest. We fear that the same thing is also happening with turkeys, ducks and geese.

How many regain consciousness?

N.G. Gregory says that, "some authorities take the view that, from the welfare standpoint, it is best to induce a cardiac arrest at stunning in at least 90% of birds." (30) However, some plants are now using a system of high frequency stunning which only aims to stun birds rather than kill them by cardiac arrest.

If we take the optimistic view that 90% of birds have a cardiac arrest at stunning and are unconscious until they die, 62 million electrically stunned birds will not have a cardiac arrest. They will be stunned for 60 seconds but they will not die for almost 3 minutes and so they will regain consciousness.

62 million chickens, turkeys, ducks and geese are regaining consciousness in British abattoirs each year.

How many birds are conscious when they enter the scalding tank?

Let's assume that birds will only be conscious on entering the scalding tank if they have one carotid artery cut at slaughter. In this case they will take around 5 minutes to die yet legally they only have to be left to bleed out for 2 minutes. They will regain consciousness after only one minute.

14 abattoirs appear to use automatic neck-cutters which only sever one carotid artery. 73.9% of these - or 10 abattoirs - will use the electric waterbath. If these abattoirs slaughter 10% of birds they will kill 84 million birds a year. 90% will have a cardiac arrest at stunning, leaving 8.4 million who will only have one carotid artery cut and will therefore be conscious on entering the scalding tank.

8.4 million chickens, turkeys, ducks and geese are conscious when they enter the scalding tank.

Constant current waterbath stunners

One of the problems with electrical stunning is that the amount of current which passes through each individual bird varies according to the impedance of the bird to the current. Mohan Raj says that a waterbath stunner that can deliver a present constant current to each bird in the waterbath has been developed recently and believes that this improvement could enhance bird welfare (63). Two years later, Viva! wrote to the Meat Hygiene Service to ask whether UK abattoirs are using these new stunning systems. Principal MHS OVS Jane Downes replied that she did not hold any information on this subject. (69)