Lighting conditions in poultry houses profoundly affect broiler and laying hen welfare, influencing natural behaviour, health, and productivity.
Lighting is a powerful but often overlooked welfare variable in poultry farming. Chickens have acute colour vision different from humans - their response to different light spectra affects behaviour, stress levels, and activity patterns. Inadequate darkness prevents normal sleep cycles essential for immune function and physical recovery. Excessive light intensity causes eye problems and increases fearfulness. The welfare improvement achievable through appropriate lighting - adequate darkness duration, species-appropriate spectrum, and natural variation - is significant and technically simple to implement. Higher welfare certification schemes recognise this by including lighting standards as a condition of accreditation.