White and brown layer pullets’ choice of light intensity in relation to their behaviour, age and the time of day

For chickens, one of the most important senses is vision and light can influence their behaviour, welfare and productivity. For laying hens, lighting needs will differ depending on the stage of development of the bird, i.e. rearing vs production. The rearing period is essential in the preparation of laying hens for a sustainable laying period with optimal welfare. However, there is little knowledge regarding layer pullet preferences for light intensities. Therefore, we identified white and brown layer pullets' responses to different light intensities in relation to their behaviour, age and the time of day via preference testing. Day-old chicks from a white (Lohmann LSL Classic) and brown (Lohmann Brown Classic) layer breed were housed till 10 weeks of age (woa) in groups of 24 per pen (8 m²) and seven pens per breed. Pens were divided into four equal sections, with one light intensity per section that switched daily (intended light intensities: 5, 20, 50 and 100 lux, actual light intensities: 8, 35, 80 and 220 lux) and an opening in the centre to all sections. An algorithm automatically counted the number of pullets per section for two days per week (week 2 till week 10) from recordings of each pen. Behaviour was observed via scan sampling at six ages (weeks 1, 2, 4, 6, 8 and 10). White and brown pullets showed more active behaviours (i.e., standing, locomotion and foraging) at higher light intensities, while inactive behaviour was shown more at lower light intensities, suggesting zones for specific behaviours can be created within a pullet house using light intensity. White and brown pullets preferred high light intensities throughout the experimental period, which was more clear for brown than for white pullets, suggesting it may be important to adapt light intensity programmes to each breed. At the start and end of the light period, high light intensities were preferred by white and brown pullets, which was again more clear for brown than white pullets, suggesting it may be important to adapt light intensity programmes to the time of day. Interestingly, pullets from both breeds were always present at each intensity, suggesting that providing pullets a choice in light intensity may improve their welfare.