2 Flashcards
Legislation regarding position of captive bolt?
Must position in a way to ensure the projectile enters cerebral cortex.
NOT in back of head.
Ideal position of captive bolt for cattle?
- why?
At the intersection of 2 imaginary lines drawn from the top of the eyes to the base of the opposite horn bud.
- only a thin layer of skin over this point of the skull so bolt not slowed before hitting solid bone.
- less sinuses so less energy absorption.
- good position to direct bolt to the midbrain.
Position of stunning for sheep (without horns)?
Highest point of head and aim towards angle of the jaw.
Position of stunning for sheep with horns?
Back of the head (POLL POSITION).
If shot in normal position, go through huge sinuses that are designed to absorb impact.
MUST STICK WITHIN 15 SECONDS!
Stunning position for pigs up to 100-110kg.
Aim 2.5cm above a line drawn between eyes, on the midline.
Stunning position for older boars and sows.
Aim 5cm above a line drawn between the eyes, OFF MIDLINE!
Difference between red meat (cattle, sheep) and white meat (pigs, chickens, turkeys).
Red meat slower twitch muscle fibres.
White meat faster twitch muscle fibres.
- start kicking immediately after stunning – only in emergencies.
- use of gas stunning instead – to affect brain and spinal cord at same time so no kicking –> less damage to the carcase.
Recognition of effective mechanical stunning.
Loss of posture (legs come up and animal drops).
- affected midbrain.
Tonic/clonic activity - still then kicking.
No rhythmic breathing - affected medulla.
No corneal reflex - affected reticular activating system.
Fixed, glazed expression to the eyes.
Legislation regarding recognition that the stun has been ineffective.
Appropriate back-up equipment immediately available on the spot and is used in the case of failure of the stunning equipment initially used.
Back-up method may differ from that first used.
The same piece of equipment must not be used.
What animals do captive bolt pistols not work very well with and why?
Water buffalo - average distance between outer skull and brain = 7cm of shock-absorbing sinuses.
Horses - skull is too thin for impact.
– use free bullet instead.
–> immediately kills.
Why use electrical stunning?
Allows for high through-puts.
Allows minimal damage when stunning pigs.
Cheaper.
Term for electrical sunning?
Electronarcosis.
Description of head-only electrical stunning?
Exposure of the brain to a current generating a generalised epileptic form on the electroencephalogram (EEG).
Overstimulation of brain function.
A form of simple stunning using spikes or tongs.
- electricity passed between the spikes.
- definitely recover if not bled.
What is the “stunned state” following electronarcosis?
Action of applied high voltage waveform on neural tissue will disrupt normal membrane activity and produce brain dysfunction immediately.
Tonic/clonic epilepsy, which is associated with unconsciousness occurs.
How is epilepsy generated neurologically?
Massive NT release.
Chain reaction in the brain.
Phases of electrical stun.
Brain dysfunction occurs 15-20 ms swinging voltage disrupts normal brain activity.
Then in 200 ms, over generation of aspartate and glutamate produces overstimulation of synapses
- global epilepsy.
(Pre-stun, stunning w/ monitoring off, post-stun high amplitude low frequency activity, EEG suppression, return to rhythmic breathing).
First sign of recovery from electrical stunning?
Rhythmic breathing.
Then response to pain.
Then consciousness.
Phases of epilepsy post electrical stun.
Tonic phase:
- stiff muscled, front legs extended, hind legs flexed into body.
…..10-12 seconds….
Clonic phase:
- uncontrolled physical activity.
*no rhythmic breathing throughout both phases.
Minimum current to stun…
1. bovine >6m.
2. bovine <6m.
3. ovine or caprine.
4. porcine.
5. chickens.
6. turkeys.
- 1,28A.
- 1,25A.
- 1,00A.
- 1,30A.
- 240 mA.
- 400 mA.
Positioning of the spikes or tongs in electrical stunning?
Eye and ears.
Flow electricity down optic nerve and auditory canal to cross brain.
Electricity does not flow through bone.
How long are the tongs held on the animal at electrical stunning and why?
3 seconds to allow spreading electrical field to depolarise spine, reducing the post-stun clonic activity.
Basics of Head to Body (cardiac arrest) stunning?
Electrical stun / killing methods involve induction of cardiac ventricular fibrillation (rapid and irregular beating of the heart), by passing an electric current across the heart in unconscious animals that have been stunned by a head-only application.
- this prevents recovery.
- timing to bleeding matters less.
- more spinal cord affected so kicking reduced too.
- not approved for Halal as is non-recoverable method, provided current is sufficient.
Why are there still regulations on stun-to-stick interval, even when Head to Body Stunning is carried out?
To void the body of blood as quickly as possible to improve carcase quality.
