The behaviour of broiler chickens in different light sources and illuminances

Most broiler chickens are reared commercially in artificial light environments, which differ sharply from the natural light environment in which they evolved. It is not known how light affects the behaviour of broiler chickens, despite much research in the past. Here, we describe two experiments aimed at assessing how commercially available light sources at set illuminances influenced the behaviour of broiler chickens. In the first experiment, the preferences of four groups of six broiler chickens for four different light sources at two illuminances were assessed when the birds were 1 and 6 weeks of age. Broiler chickens of 6 weeks of age preferred to occupy biolux and warm-white fluorescent light sources over incandescent and spectral-sensitivity matched light, irrespective of the light intensity. In the second experiment, eight groups of 275 broiler chickens were reared semi-commercially in either of their two preferred light sources from Experiment 1 at either bright or dim illuminances (5 or 100 clx, adjusted to fowl perceived illuminance). Broilers showed a fairly resilient time-budget across light sources and intensities, whereas age and time-of-day affected most behaviours recorded. The birds spent 61% of their time resting in the litter at 6 weeks of age but resting was not significantly affected by light source or illuminance. However, the broilers showed less feather-pecking behaviour in warm-white rather than biolux light and more foraging behaviour in dim rather than bright light intensities. The two experiments combined different experimental designs to encompass potential intervening environmental variables and thereby strengthening the application of behavioural research to industry.