Over the years, demand for eggs has continued to increase steadily, simultaneously stimulating production. In 2020, there were more than 350 million laying hens in the European Union with production close to 6.7 million tonnes of eggs per year (European Commission, 2024). In so-called commercial, intensive production systems, animals are either reared in cages, aviaries or free-range houses. By EU law (Council Directive 1999/74/EC), all laying hens should be provided access to perching and nesting space, litter to allow for behaviours such as pecking, dustbathing and scratching behaviours, and have unrestricted access to water and feed, irrespective of what housing system is used. As of 2012, conventional cages have been prohibited by the European Union, and animals can now only be kept in the so-called enriched cages which guarantee that each animal has at least 750 cm2 of (cage) area. The alternative systems for their part (aviaries and free range systems) allow the birds to move freely with stocking densities that do not exceed nine hens per square meter (equating to at least 1111 cm2/bird) (Council Directive 1999/74/EC).