1 Flashcards
Legislations of slaughter.
European:
- EC1099/2009 on protection of animals at time of killing.
UK:
- Welfare of Animals at the Time of Killing Regulations 2015.
General principles of slaughter legislation?
It is an absolute offence to cause or permit an animal avoidable excitement, pain or suffering.
- specific rules on handling, stunning, slaughter or killing of animals. In particular:
– anyone carrying out any of these tasks must have the knowledge and skill to do their job humanely and efficiently.
– slaughterman must be competent and hold a certificate of competence for the roles they conduct.
– in every slaughterhouse, a competent person must be given authority to take action to safeguard welfare.
–> animal welfare officer.
—> must record actions and make available for viewing by government vet whenever asked.
– only permitted methods may be used to stun or kill animals.
Define stunning.
Any intentionally induced process which causes loss of consciousness and sensibility without pain, including any process resulting in instantaneous death.
Why must the loss of consciousness and sensibility be maintained until the animal is dead?
Extreme pain will be experienced if the animal regains consciousness.
Simple stunning vs stunning.
Simple = Stunned but may or may not be dead as a result.
Must bleed animal as quickly as possible so that they do not regain consciousness before they are dead.
Stunning = stunned and not recovering, dead.
In stunning, what is meant by “without pain”?
A procedure which produces brain dysfunction before the animal can feel procedure or any effect of the procedure.
How long does it take for a painful stimulus to be recognised as painful?
~100 ms.
What is meant by consciousness?
Variously defined as subjective experience, awareness, ability to experience “feeling”, wakefulness, or executive control system in mind.
An animal can be presumed to be unconscious when it loses its natural standing position, is not awake and does not show signs of positive or negative emotions such as fear or excitement.
How is unconsciousness achieved?
By inducing dysfunction to:
- the cerebral hemispheres on a large scale.
- the reticular formation.
- ascending reticular activating system or median thalamus bilaterally.
What is meant by “death”?
Brain-death.
- no clinical evidence of brain function upon physical exam.
- no responses to pain, no cranial nerve reflexes.
– incl. pupillary response (fixed pupils), oculocephalic reflex, corneal reflex.
- no response to caloric reflex test.
- no spontaneous respiration.
– no rhythmic breathing.
Can we measure death.
EEG measures brain voltage in microvolts.
All positive responses suggest brain function. Cortical death occurs when EEG is silent.
Test w/ visual evoked potential.
- a measure of ‘residual consciousness’ that can be used to obtain objective measures of brain death.
Our definition of stunning?
Brain dysfunction which occurs within 100-150ms of application of a method that continues until cortical brain death.
Signs of brain dysfunction.
Loss of posture.
No rhythmic breathing.
No corneal reflex.
No response to pain.
Kicking - brain not controlling spinal cord anymore.
Methods of stunning.
Mechanical.
Electrical.
Gas.
Other - lethal injection not allowed.
Stunning options for red meat.
Controlled atmosphere (gas).
Captive bolt.
Electrical stunning.
Why did mechanical stunning first begin?
Health and safety of personnel when slaughtering cattle.
- large size.
Nothing to do with welfare.
First used pole-axes / felling hammers.
- banned in 1933 in UK as bad welfare – lots of hits required to knock animal down.
Bruneau mask.
Animal cannot see what is happening.
Bolt in right place.
Hit bolt to stun.
Difficult to get mask onto animal.
Captive bolt.
- Easily accurate.
Same results, same speed each time.
Blank cartridge, piston, captive bolt, rubber ring to take back out of head.
Types:
- penetrating.
- non-penetrating.
- trigger fired.
- contact fired.
How does captive bolt work?
Energy of bolt (by virtue of speed), accelerates the skull but not the brain.
The brain (floating in CSF) accelerates a fraction of a second after the skull (differential acceleration).
Effects of concussion (whether penetrating or not) will cause increases and decreases in pressure in the skull.
First, impact causes shockwave through brain provoking pressure gradients leading to tears and lesions in brain tissue and disturbances in blood flow.
Immediate potassium efflux induced resulting in depolarisation of the neurons of cerebral hemispheres (and brainstem depending on the impact).
Secretion of excitatory NTs and a calcium influx into cells, disrupting mitochondrial function and energy production.
Shock wave can push brain tissue through opening of tentorium resulting in compression of brainstem - may cause slowing or cessation of breathing and cardiac function.
Following concussion, bolt causes local skull fragmentation and crushes brain tissue and blood vessels in its trajectory.
The retraction of the bolt temporarily leaves a void in tunnel created by its passage that sucks in surrounding brain tissue causing further tearing of axons and blood vessels.
Haemorrhage further deprives certain brain structures of blood supply, and lack of nutrients and oxygen disturbs the inter- and intra-cellular biochemical balance.
Captive bolt - how long does it take?
1.5 ms.
(100x faster than the animal can feel it).
What is the difference between penetrating and non-penetrating captive bolt?
More likely to recover from non-penetrating than non-penetrating.
Factors affecting gun performance.
Kinetic energy = 1/2 mv^2.
Where m = mass of bolt.
- if doubled, double kinetic energy.
Where v = bolt velocity.
- if double velocity, quadruple kinetic energy.
But velocity can be affected by a number of other factors:
- choice of cartridge, is cartridge fresh, clean?
