Today in Europe, there are 354 million commercially bred laying hens, 30% of which, according to the prognoses of EUWEP (EUWEP, 2011) are still kept in conventional battery cages in 2012 Due to the limitations imposed on the cage rearing systems for layers in the EU, the value of an egg produced here is higher than the price of an egg imported into the EU from Asia, North America or South America (Horne and Bondt, 2003)