Light intensity preferences of broiler chickens is affected by breed, age, time of day and behaviour.

Light is an important aspect of broiler husbandry and management as it influences behaviour and welfare. However, a lot remains unknown regarding broiler preferences for light intensities, especially for slower-growing broilers which are increasingly used in broiler production systems in the EU. We identified preferences of fast (F)- and slower (S)-growing broilers for intensities in relation to behaviour, age and time of day. Broilers were housed in pens with four sections, each having one intensity (0.2, 20, 50 or 1000 lx). Both breeds showed more active behaviours at higher intensities and more inactive behaviours at lower intensities. They preferred higher intensities when young and lower intensities when older, with S broilers preferring the lowest intensity more when older. They preferred higher intensities at the end and start of the light period, with F broilers preferring the highest intensity more when young and S broilers more when older. Thus, light intensity could be used to create functional zones within a broiler house for specific behaviours and light intensity programs could be adapted to age and time of day, taking into account breed differences. Furthermore, broilers were always present at each intensity, suggesting individual preferences and offering a choice might be beneficial for broiler welfare.