Modelling the dynamic activity of broiler chickens in response to step-wise changes in light intensity

Controlling activity in broiler chickens may provide an inexpensive tool with the potential to improve broiler welfare by reducing lameness, reducing injuries during catching as well as increasing synchronisation within the flock. Despite much attention, no method has so far been able to control activity in broilers successfully at production level. In this study we used dynamic mathematical modelling to predict how broilers transfer temporal step-wise variations in light intensity into activity responses. We carried out three experiments in order to assess the effects of age, sex and experience upon steady-state and dynamic responses of activity to step-wise variations in light intensity between 5 and 100 lx. Most of the dynamic responses followed first-order dynamics, suggesting that only one overall process is involved in transferring light input into activity. The broilers showed significantly higher activity during periods of 100 lx than 5 lx when intensity alternated. Activity decreased with age but not with experience of the light regimes. The broilers responded significantly faster to a step-up than to a step-down in light intensity. Overall, the results suggest that a combination of step-wise variations in light intensity and the dynamic data-based modelling technique could provide additional information on the ethological mechanisms controlling broiler activity. This is encouraging for predicting and controlling activity, which could improve the welfare of broiler chickens on the farm.