Lighting conditions in broiler chicken houses profoundly affect bird welfare. Evidence now clearly supports minimum dark periods and light intensity standards that improve welfare outcomes.
Broiler lighting management illustrates how seemingly minor husbandry details can have large welfare consequences. The practice of near-continuous lighting was adopted to maximise food intake and growth rate, but caused birds to be chronically sleep-deprived, leading to elevated stress hormones, impaired immune function, and abnormal behaviour. The scientific evidence for a minimum dark period is now robust and has driven legislative change in the EU and elsewhere. Beyond simple dark periods, lighting intensity and spectrum matter: dim lighting during dark periods allows proper sleep, while appropriate daytime intensity encourages natural activity that promotes leg and cardiovascular health. Modern welfare-centred lighting programmes cost producers little but deliver measurable welfare benefits — a clear win for evidence-based animal welfare policy.