Li, G., Li, B., Shi, Z. et al. 2020. Diurnal rhythms of group-housed layer pullets with free choices between light and dim environments. Canadian Journal of Animal Science 100(1), 37-46.

Chickens under appropriate light–dark programs can develop diurnal rhythms. However, actual needs of layer pullets for the light and dark environments are not fully understood. This study was to investigate the diurnal rhythms of pullets in the light (30 lx) and dim (<1 lx) environments. The preferences of pullets on the light and dim environments were examined. The testing system contained four identical compartments (0.96 m length × 1.20 m width × 2.00 m height for each). A light-emitting diode tube, a camera, and weighing sensors were installed in each compartment. Four groups of eight Chinese domestic layer pullets, Jingfen, were used at the weeks 15–18. Choices of environments and feeding behaviors were monitored by weighing sensors, and activity was measured by digital image processing. The results show that pullets spent on average 35.5 ± 2.2 min under the light and 24.5 ± 2.1 min under the dim in each hour. Human inspection can stimulate bird feeding and activity. Overall, pullets behaved more actively under the light than under the dim environment. Pullets stayed in the light and dim environments throughout each hour of a day, which may suggest that lighting environments with free choices in a pullet house might better serve for pullet preference.