As activity levels of intensively managed broiler chicken vary over time, detailed knowledge on their influence is potentially useful to further adjust welfare assessment schemes. Therefore, this study investigated the influence of daytime and age on the performance of broiler chicken in applied fear tests.

On-farm studies were carried out in 14 flocks of intensively managed broiler chicken, eight of a fast-growing and six of a slow-growing strain. In each flock, a forced and a voluntary approach test were conducted and at each observation, the avoidance distances (AD) and the number of animals voluntarily approaching (VA) an observer were collected.

The effect of differing observer locations in the chicken house on the behavioural response of slow-growing broiler chicken was measured in Experiment 1. Additionally, the influence of daytime in the avoidance and approach behaviour was observed. A higher proportion of birds voluntarily approached an unknown human in the area close to the main entrance door, but the avoidance behaviour was not affected. Further, daytime influenced both the approach and avoidance behaviour (AD: r= -0.21, p= 0.00; VA: r= 0.48, p= 0.00) with a longer AD in the morning but a higher approach in the evening.

The major objective of the present study was addressed in Experiment 2, in which the repeatability of approach and avoidance behaviour of Danish broiler chicken within days and at different times in the rearing cycle (1: 6-12d; 2: 21-24d; 3: prior to slaughter) was investigated. No significant correlation was found between daytime and AD or VA. Both, approach and avoidance peaked at three weeks with the latter decreasing to a minimum prior to slaughter.

As activity and behaviour are known to vary over the day, detailed knowledge on their influence is potentially useful to further adjust welfare assessment schemes. From the results of this study I conclude, that the time of assessment has no effect on avoidance or approach behaviour of commercial broiler chicken, that are managed under artificial light conditions. This makes the applied tests potentially applicable independent of time restrictions.