Lighting management in poultry production profoundly affects bird welfare through its influence on behaviour, health, and biological rhythms.
Lighting is a frequently overlooked dimension of poultry welfare with profound impacts on bird health and wellbeing. Continuous or near-continuous lighting was adopted because it maximizes feed intake and growth rate, but it causes chronic disruption of circadian rhythms, leading to immunosuppression, increased leg disorder rates, and behavioral abnormalities. Chickens deprived of adequate dark periods show signs consistent with chronic stress and fatigue. Evidence demonstrates that providing minimum 4-hour dark periods significantly improves bird welfare without unacceptable production losses. Higher-welfare standards now typically specify minimum darkness, minimum light intensity, and wavelength requirements - these provisions translate directly to measurably better bird welfare outcomes.