Lighting programmes in broiler sheds significantly affect bird welfare, with continuous darkness or very low light reducing activity but also masking health problems and abnormal behaviours.
Light management in broiler sheds creates a welfare trade-off that producers have historically resolved in favour of low light to reduce activity and aggression. However, very low light levels reduce natural behaviour, impair welfare assessment by stockpeople, and may mask developing health problems. Evidence-based light programmes using appropriate intensity, duration, and spectrum improve welfare outcomes while managing aggression through other means including enrichment and appropriate stocking density.