INTRODUCTION
We can define animal welfare by different parameters such as birds’ health, behavior or production. Due to new animal welfare regulations, alternative management systems or cage free environments has becoming a common practice in egg production. There are few alternative systems introduced to the layer industry. It is clear that cost of egg production is much higher in cage free systems because of high number of downgrade eggs (Appleby et al., 2002, Gueston and Faure, 2004). Studies are addressing the management side of the problem such as different cage densities, effect of rearing factors, and different cage or nest types (Appleby et al., 2002, Gunnarsson et al., 1999, Guesdon and Faure, 2004). Cooper and Appleby (1996) were the first who studied individual bird differences on floor laid behavior, and showed that incidence of floor eggs declines with age.
