Light intensity, duration, and spectrum profoundly affect the behaviour, physiology, and welfare of farmed animals; evidence-based lighting design is one of the simplest environmental welfare improvements available.
Lighting is often used as a production tool — to accelerate growth, delay maturation, or suppress behaviour — without adequate consideration of welfare impacts. Bright light enables foraging and social interaction but can also increase aggression in crowded conditions. Welfare-optimal lighting regimes balance activity stimulation with reduction of injurious behaviour and adequate provision of dark rest periods.