Housing systems and welfare in laying hens

Production systems for laying hens have totally changed during the last century with the emergence of conventional cages. In this bare environment, hens are not able to express their normal behaviour. In this review, we discuss the technical challenges associated with the welfare of laying hens, and we show that housing systems need to be considerably modified in order to improve welfare, which can in turn have a significant impact on production. Moreover, since poultry production involves very large flocks, specific housing conditions are required. In 1999, EU-directive (1999/74/CE) fixed the minimum housing standards for laying hens (space allowance, litter, nest and perch availability). Utilisation of new systems such as furnished cages and alternative systems can lead to better hen welfare, but other factors must be taken into account, such as human health and egg quality, and even other aspects of bird welfare itself (e.g. cannibalism).