FAQ

1. Why use carbon dioxide (CO2) instead of electric stunning?
2. Is it necessary to use as high a concentration of CO2 as 80-90%?
3. How does inhalation of high concentrations of CO2 affect the pigs?
4. Is it possible to use the same anaesthetic on pigs as is normally used by doctors on human beings?
5. Are the animals suffocated by carbon dioxide?
6. Will some of the pigs die during anaesthesia with CO2?
7. British tests have shown that pigs get uneasy or even try to escape when they are lowered down into the CO2-atmosphere. Is this normal?

1.  Why use carbon dioxide (CO2) instead of electric stunning?

Stunning by CO2 is more "humane" to the pigs. By electric stunning the pigs are normally stuck in traps, which is causing much stress. This is one of the reasons for a better meat quality by using CO2, as less stress means less muscular bleeding, less fresh bone fractures and less PSE meat.

2.  Is it necessary to use as high a concentration of CO2 as 80-90%?

Yes, as a high concentration of CO2 means quick loss of consciousness (normally after 20 sec.) and therefore little time for anxiety and discomfort.

3.  How does inhalation of high concentrations of CO2 affect the pigs?

We do not know for sure, but experience from Denmark, Sweden and Germany does not indicate any significant uneasiness among pigs being stunned by high concentrations of carbon dioxide.

4.  Is it possible to use the same anaesthetic on pigs as is normally used by doctors on human beings?

No. The anaesthetic used on human beings is absorbed by the fatty tissue and will not be liberated in time before the pigs are killed, and medicine residues are not allowed in slaughter pigs. However, carbon dioxide is a natural metabolic product in the body of the animal.

5.  Are the animals suffocated by carbon dioxide?

No. Even in moderate concentrations carbon dioxide has an anaesthetic effect on the brain. Suffocation is normally caused by lack of oxygen, and investigations have shown that the concentration of oxygen in the blood does not go below the critical limit by using carbon dioxide.

6.  Will some of the pigs die during anaesthesia with CO2?

It is quite natural that living creatures react differently to a certain treatment. It can therefore not be excluded that some pigs will not wake up after the anaesthesia. However, the anaesthesia must under all circumstances be so deep that all pigs are unconscious until they die from bleeding.

7.  British tests have shown that pigs get uneasy or even try to escape when they are lowered down into the CO2-atmosphere. Is this normal?

No. Experience from Denmark, Sweden and Germany reveales no uneasiness and no such reactions as described above. These tests in UK were made with few pigs and in laboratories, and they have formed basis for the criticism of stunning with carbon dioxide.

The answers have been prepared by the Danish Meat Research Institute