Lighting programs in commercial turkey housing significantly affect turkey welfare, circadian rhythm integrity, and the incidence of welfare-compromising behaviors.
Commercial lighting programs designed to maximize feed intake created chronic welfare harms through circadian disruption that were long overlooked. Turkeys under continuous bright lighting show elevated fearfulness, reduced positive welfare behaviors, and higher rates of injurious pecking compared to those given adequate dark periods. The transition to better lighting programs costs little but delivers measurable welfare improvement. Natural light access provides additional welfare benefit through visible spectrum variation that artificial light cannot replicate.