News 658 views last update:Apr 12, 2007

Pigs don't see better with more light

Research has revealed that increasing light intensity from 12 to 40 lux does not enhance the pigs' sight.

This conclusion was drawn by the Animal Sciences Group (ASG), a part of Wageningen University and Research Centre in the Netherlands.

Pigs were tested for their sight by giving them the choice between two feeders, the full one consistently marked 'C', the empty one consistently marked 'O'.

As soon as the animals knew the meaning of these signs, the scientists used different sizes of letters and different light intensities.

Letter size appeared to have a strong effect, light intensity however did not play a role in the animal's decisions. Only when light intensity dropped to less than 1 lux, the animals started to make mistakes.

Pigs are known to be predominantly shortsighted. For that reason their ears and nose are much more important for pigs to find feed.

ASG did this study to find out whether the increase from 12 to 40 lux, legally imposed in the Netherlands in 2003, was beneficial to the pigs' ability to perceive the world around them.

EU guidelines
The 40 lux law is in accordance with EU guidelines, stating that the pig barn should have 40 lux light for at least for eight hours a day. Annually, the increase to 40 lux costs about €0.60 per pig place for energy expenses.

The study was conducted at the request of the Dutch product boards for livestock, meat and eggs (PVE).

Related websites:
• Dutch product board for livestock, meat and eggs (PVE)
• Animal Sciences Group (ASG)
• Wageningen University and Research Centre

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