Does a pig suffer when it is being stunned with gas? Not necessarily, according to Dutch agriculture minister Gerda Verburg.

Radio Netherlands reports that Socialist Party member of parliament, Krista van Velzen, has raised questions about a carbon dioxide gas anaesthesia used in Dutch slaughterhouses.

In response to the questions, Ms Verburg wrote a letter to parliament explaining, "There doesn't have to be a direct relationship between a level of unconsciousness and the observable symptoms [...] It can visually appear like animals are experiencing inconvenience while in fact they are unconscious."

Discussions were fuelled by video footage released by animal welfare organisation 'Varkens in Nood' (Pigs in Distress). The video shows an experiment at the University of Zurich involving a pig that was conditioned to feed in an isolated and sealed space. On a given day, however, the pig is greeted not with its usual plate of food, but a gradual stream of the carbon dioxide gas anaesthetic instead. Footage shows the pig frantically jumping up and down trying to breath, until it drops down exhausted. After the anaesthesia wears off, the pig refuses to re-enter the room to be fed and opts instead to go without food and water for three days.

The Animal Rights political party, which holds two out of the 150 seats in the Dutch parliament, has called for a ban on this method of anaesthesia. Minister Verburg, in line with European regulations, says she has no intention of prohibiting the anesthesia.

Two methods of anesthesia are currently allowed in the Netherlands before a pig is slaughtered by having its throat cut and then bleeding to death instantly: gassing and electrocution.

According to the largest slaughterhouse company in Europe, Vion, both methods have their downsides. Electrocution is quick, but has to happen to each pig individually. Whereas a gas anesthetic takes 10 to 20 seconds, but the abattoir can anaesthetise the pigs in groups, thereby removing the need to separate the social animals from their groups.

'Varkens in Nood' says that it is impossible to examine the exact suffering of the animals because the anaesthetics are given behind closed doors. The organisation says this lack of transparency is a breach of European regulations.

Minister Verburg is resisting calls for cameras in the cells. She says control and registration of the gas used as well as the "visual assessment of the animals coming out of the rooms" is more effective than "judging the animals on camera". The animal rights organisation claims this alone is proof that the anesthetic method does not bare scrutiny, concludes the Radio Netherlands report.