Decades of research on laying hen behaviour has identified specific environmental resources — perches, nest boxes, litter, and foraging substrates — that are essential for welfare. Understanding the science behind enriched environments helps evaluate which systems genuinely serve hen needs.
The scientific evidence on laying hen welfare is clear that no single housing system is without welfare costs, but that access to specific key resources — nest boxes, perches, foraging substrate, and sufficient space — is essential for meaningful welfare improvement. The transition from conventional battery cages was scientifically justified by strong evidence that hens are highly motivated for resources those cages denied. However, the design and implementation of enriched systems matters enormously. Enriched colony cages meeting only minimum EU specifications leave many hens without practical access to nest boxes and perches due to competition and inadequate provision ratios. Aviary systems, when well-managed with appropriate light levels, litter quality, and stocking densities, can achieve significantly better behavioural welfare than either battery or enriched colony cage systems. The science supports continued evolution of standards toward systems that allow genuine expression of the full behavioural repertoire rather than legal minimum compliance.