Light preferences of broiler chickens across functional zones in the broiler house

Lighting plays a crucial role in the welfare and performance of broiler chickens, influencing growth, behaviour, and physiological responses. While numerous studies have examined the effects of monochromatic light on performance parameters, little is known about broilers' active light recipe preferences when given a choice, particularly in relation to functional zones of the housing environment. This study investigated broiler chickens' light recipe preferences across four functional zones: feeding, drinking, resting, and scratching area using a dynamic light-emitting diode system. A total of 1680 male ROSS 308 chicks were reared over four consecutive production rounds with four pens per round under controlled environmental conditions. Each pen contained four functional zones equipped with three distinct light recipes per zone: one control (white 3000 K) and two test light recipes that rotated between rounds to avoid location bias. Locations of the chickens were obtained through continuous video monitoring and object detection using the You Only Look Once (YOLO) algorithm, resulting in over 500 million individual bird detections. Results showed that occupation of functional zones varied with age: feeding and drinking areas were most used in the starter phase, while resting and scratching areas gained prominence as birds aged. Light colour significantly affected occupancy within each functional zone. In feeding areas, birds consistently avoided red light during starter and grower phases, preferring control and cyan lights. There was a tendency for control light to be preferred over yellow and cyan in the drinking areas. In areas designed to promote comfort behaviours, such as resting or preening, whether facilitated by platforms or not, birds consistently preferred cold white light (8000 K) across all phases. No consistent light preferences were observed in scratching zones designed to elicit foraging and play behaviours, although a relative preference for white+UV light was observed during the grower phase. These findings demonstrate that broilers exhibit zone- and age-specific colour preferences, emphasising the importance of specific lighting strategies to enhance welfare and behaviour in commercial poultry housing systems, such as omitting red around feeding zones and using cold white colours in zones that promote comfort.