Simplified version of Claudia Terlouw’s text
Full original text available at: https://www.viandesetproduitscarnes.com/index.php/fr/
Introduction
Every year, millions of animals (cattle, sheep, pigs, poultry) are slaughtered for meat consumption. This takes place in slaughterhouses subject to strict European regulations (Regulation EC No. 1099/2009), which require compliance with animal welfare rules.
The general rule is that animals must be stunned before killing, so that they lose consciousness and do not feel pain. However, a derogation exists for certain religious slaughter practices.
This text aims to explain, in simple terms, what science teaches us about consciousness, unconsciousness, and the effects of different stunning methods.
I. Understanding Consciousness and Unconsciousness
Consciousness is the ability of an animal (or a human) to be aware of what is happening around them and to feel emotions such as fear, hunger, or pain. It results from the work of several brain areas processing sensory, memory, and emotional information together.
Loss of consciousness occurs when the animal can no longer perceive or respond to its environment. It can be complete (total unconsciousness) or partial (drowsiness, weak or inadequate responses).
Three main brain areas are involved:
- The cerebral cortex, which analyzes sensory information (sight, hearing, touch, smell…) and decides on actions to be taken.
- The thalamus, which serves as a “relay” between the body and the cortex.
- The reticular formation in the brainstem, which acts as a “main switch” for wakefulness and consciousness.
If one of these areas stops functioning (due to injury, shock, or artificial stimulation), the animal loses consciousness.
II. Stunning: Purpose and Principles
1. Why stun an animal?
The purpose is to render the animal unconscious so that it feels neither fear nor pain during bleeding. Stunning must be rapid and last until the animal’s death.
2. How does stunning work?
It abruptly disrupts brain function:
- either by creating a direct mechanical shock,
- or by blocking the electrical activity of neurons,
- or by altering the composition of the blood (through gas or blood loss).
III. Different Stunning Methods
1. Mechanical stunning (captive bolt pistol)
A metal rod is propelled into the skull.
- This causes a shock wave that “short-circuits” the brain.
- Loss of consciousness is almost instantaneous, before the animal has time to feel pain.
- When properly done, the animal never regains consciousness.
2. Electrical stunning (electrocution or electronarcosis)
Electrodes are placed on the head (or head + body).
- The current induces a seizure that blocks consciousness.
- The animal becomes unconscious in less than one second.
- If the current is strong enough, unconsciousness lasts until bleeding is completed.
- But if electrodes are poorly placed or the skin is too dry, the effect may be incomplete and the animal may regain consciousness.
3. Gas stunning (CO₂)
Animals (mainly pigs and poultry) are placed in a chamber filled with carbon dioxide.
- The gas alters the blood, gradually disturbing brain function.
- The animal loses consciousness in about twenty seconds.
- If exposure is long enough, death occurs without regaining consciousness.
- The problem: during those seconds, the animal may feel fear and breathing discomfort.
4. Bleeding without prior stunning
In some religious slaughter practices, the animal is directly cut while fully conscious.
- The brain gradually stops functioning due to lack of oxygen.
- In cattle, this process can last several dozen seconds.
- During this time, the animal remains conscious and experiences pain and distress.
IV. Timeframes for Inducing Unconsciousness
The brain needs 250 to 400 milliseconds (less than half a second) to produce a conscious perception.
- With the captive bolt pistol, loss of consciousness is even faster: a few milliseconds. The animal does not have time to feel pain.
- With electrical stunning, if the current is strong enough, unconsciousness occurs in about 200 milliseconds. But if the current is too weak or poorly applied, pain occurs.
- With gas, it takes about 20 seconds for the animal to fade out.
- With direct bleeding, consciousness can last from 14 seconds (sheep) to over a minute (cattle).
Only mechanical and electrical methods ensure instantaneous loss of consciousness.
Conclusion
Stunning is a crucial step to reduce animal suffering during slaughter.
- The most effective methods are mechanical stunning and electrical stunning, which make the animal unconscious immediately.
- Gas and bleeding without stunning are more controversial, since the animal remains conscious for several seconds and may feel fear and pain.
- In all cases, it is essential to ensure that the animal does not regain consciousness before death.