PART FIVE : SHEEP SLAUGHTER
Captive bolt rarely used for sheep
According to the MHS animal welfare survey 1997/8, "Captive
bolt stunning [sheep and pigs] is used in a high proportion
of slaughterhouses, however, these were mainly low throughput
premises and represent a very small percentage of the national
Repeat Stuns and Mis-stuns
According to the MHS, the majority of sheep in British abattoirs
are stunned using the head-only electrical method. The MHS
say that the average current applied during the electrical
stunning of sheep is 1.2 amps (10). However, this is an average
figure covering both head-only and head-to-back electrical
stunning. Individual averages for each stunning system are
Stunning animals who are unrestrained in a pen with electric
tongs is not a straightforward procedure. In a busy, crowded
slaughterhouse environment where staff are untrained, sheep
routinely escape the grasp of the stunning tongs. The brief
application of the tongs will give them a painful electric
shock rather than a stun.
A scientific paper published in the British Veterinary Journal
in 1984 observed stunning in over 9,000 sheep being killed
at 40 abattoirs. They found that in the abattoirs using electrical
stunning there were 467 interrupted stunnings which, "often
occurred immediately after the first application of the stunning
tongs; the sheep fell to the floor slipping out of the grasp
of the tongs". (36) Clearly, mis-stuns are a big problem.
The researchers also saw 109 sheep who were electrically
stunned on two or more separate occasions. 37 sheep fell from
their shackles between the stunning and sticking points and
59% of these were restunned because of it.
Larger abattoirs now operate conveyor belt systems so that
animals are restrained as they approach the stun-operator.
However, Miriam Parker from the Humane Slaughter Association
said to Viva! this year that, "the problems of double-stun
or mis-stun can and do occur". (37)
Sheep regain consciousness
Assuming that an electrical stun causes some animals to lose
consciousness (see Does an electrical stun actually cause
unconsciousness, page 39 and Does electrical stunning cause
pain?, page 40), are they unconscious right up until the point
In order to calculate this, we need to look at the period
of unconsciousness produced by a stun and compare this to
the time duration between stunning and knifing and the length
of time it then takes for a sheep to lose brain responsiveness.
How long does the effect of the stun last?
C.J. Cook found that at 1.0 A, stun durations of 2 seconds
result in a seizure-like state lasting for 25 seconds in sheep
(38). Stun durations as long as 7 seconds still only resulted
in a seizure-like state lasting for 32 seconds. (38)
How long is the interval between stunning and knifing?
According to the Meat Hygiene Service 1997/8 Animal Welfare
Review, the interval between stunning and knifing recorded
in those plants using head only electrical stunning ranged
from 3 seconds to as much as 70 seconds (10). A more precise
breakdown of the figures is not given. However Gregory and
Wotton surveyed stun to knifing intervals for electrically
stunned sheep in UK abattoirs in 1984 and found that the average
interval was 21 seconds. (36)
How long do sheep take to lose brain responsiveness:
Sheep lose brain responsiveness in an average of 14 seconds
if both carotid arteries and the jugular veins are severed
(23). Some will take longer but after 27 seconds, 99% of sheep
will have lost brain responsiveness if knifed in this way.
However, UK law only requires one carotid artery to be cut
and in this case, sheep take an average of 70 seconds to lose
How long must sheep be left to bleed out for before they
can be skinned?
By law, 20 seconds.
Do sheep regain consciousness?
Using these figures, we can calculate whether sheep are regaining
consciousness before they die.
Case 1: Both carotid arteries cut
Length of seizure: 30 seconds
Time between stunning and knifing: 21 seconds
Time to loss of brain responsiveness: 14 seconds
The sheep will regain consciousness 5 seconds before she
dies. This is an "average" scenario when a sheep is knifed
according to "best practice".
Case 2: One carotid artery cut
Length of seizure: 30 seconds
Time between stunning and knifing: 21 seconds
Time to loss of brain responsiveness: 70 seconds
Time before skinning begins: 20 seconds
The sheep will regain consciousness while hanging upside
down bleeding to death. She will be conscious for 61 seconds
before she dies. Skinning may commence 20 seconds after
her throat is cut so she will still be conscious at this
Viva! fears that millions of electrically stunned sheep in
British abattoirs are regaining consciousness before they
die from loss of blood. Our fears are borne out by our video
footage, which shows clearly conscious sheep kicking and struggling
as they hang upside down on the shackle line.
Estimated number of sheep regaining consciousness
56% of plants use head-only electric stunning for sheep.
These are mainly high throughput premises so to say that they
slaughter 56% of sheep killed in the UK each year is conservative.
This adds up to 10.4 million sheep a year.
Sheep will only stay unconscious until brain death if the
interval between stunning and knifing is less than average
i.e. under 21 seconds. Half of the sheep who are stunned electrically
may therefore be knifed quickly enough to enable unconsciousness
to be maintained. This means that 5 million sheep a year are
regaining consciousness before they die.
Does an electrical stun actually cause unconsciousness?
Scientific studies have questioned whether electrical head-only
stunning does, in fact, induce a state of unconsciousness.
Studies have shown that electrically stunned sheep have periods
of responsiveness when they are fully aware of their surroundings
and what is happening to them.
Researchers at Bristol University's Department of Food Animal
Science examined whether electrically stunned sheep respond
to flashing lights following a stun. They found that, "The
epileptiform phase is interposed with periods of cortical
responsiveness and the possibility cannot be ruled out that
these correspond to transient periods of perception... There
is as yet no unequivocal scientific evidence which shows how
electrical stunning actually stuns an animal." (40)
The scientists produced a follow up paper on electrical stunning
in 1988. They electrically stunned sheep and examined whether
they then responded to "potentially painful stimuli" - like
manual pinching of the ear and electrical stimulation of the
tooth. They conclude that electrical stunning does induce
a state of analgesia (the animal will not be able to feel
pain) but this does not alter their previous observation that
electrically stunned animals have periods of consciousness
which can last up to 8 seconds (40). Crucially, they explain
that, "It was not possible to say whether responsiveness to
the potentially painful stimuli was lost instantaneously at
electrical stunning". (41) Recent scientific research has
demonstrated that because of this, the stun itself will cause
extreme pain (see page 40 - Does electrical stunning cause
The researchers conclude that, "it can be said that there
is a period of analgesia following electrical stunning. In
legal and ethical terms, this finding raises the question
of whether animals should be, 'rendered insensible to pain'
or 'rendered insensible' when they are slaughtered for meat
UK law has taken these findings into account and stunning
is now legally defined as, "any process which causes immediate
loss of consciousness which lasts until death." But does this
mean electrical stunning has suddenly begun to render animals
In January 2000, Viva! wrote to researcher Steve Wotton and
asked, "Am I right in saying that after being stunned in this
way [electric head-only stun] sheep cannot feel pain but that
they are not actually unconscious i.e. they are aware of their
Steve Wotton replied, "Your interpretation of our conclusions
is generally correct... Our experiment clearly demonstrated
the need for a change in the legislative definition... I personally
believe that this has added to our understanding of electrical
stunning and has 'tightened' the legislation... I am unaware
of further research that is specific to this area, since our
last publication". (42)
Viva! then asked, "I understand that in response to your
research, MAFF have changed legislation so that stunning must
cause an instant loss of consciousness rather than an instant
insensibility to pain. However, I'd be grateful if you could
clarify whether current electrical head-only stunning techniques
used on sheep do in fact ensure an instant loss of consciousness
- in light of your research. How can this be guaranteed if
no further research into this area has been done?"
Wotton replied, "The question that you raise regarding electrical
head-only stunning and the induction of immediate unconsciousness
in sheep has not been approached in this laboratory recently."
There appears to be no scientific evidence proving that electrical
head-only stunning renders animals unconscious.
Does electrical stunning cause pain?
Wotton and Gregory were not able to ascertain whether electrical
stunning causes an immediate insensibility to pain. Dr Harold
Hillman, Director of the Unity Laboratory of Applied Neurobiology
believes that passing an electric current through the brain
of a conscious animal is a barbaric procedure which he describes
as, "torture". (44) He says, "Of course, one cannot ask an
animal if an electric stun is painful but there is plenty
of evidence from humans subjected to large electrical currents."
He cites several examples to prove his belief that electric
stunning causes pain:
"In China, Iraq, South America and many other countries,
electricity is used to torture conscious people. Amnesty
International has documented this extensively. Indeed, I
have only recently managed to persuade the American judicial
authorities that the electric chair is painful.
"If for example you need a wart on your finger cauterised
(burnt off), your doctor gives you a local anaesthetic,
otherwise the pain would be unbearable.
"It is painful to put one's fingers across the electric
"Electricity causes burns to the skin; burns are extremely
So why is it assumed that electrical stunning is not painful?
Says Hillman, "The reasons for which people do not believe
that electrical stunning of animals or electrocution of prisoners
is painful is that the normal reaction of a conscious animal
to pain is to move violently and make loud noises. However,
the massive electrical current stimulates all the muscles
maximally and this paralyses the animal. Thus they can neither
move violently, nor can their vocal chords make noises. Their
observers naturally think that they are not in pain." (45)
Millions of animals continue to be stunned electrically despite
scientific concerns that animals are not rendered unconscious
and will suffer extreme pain when they are stunned.