The ability of domestic hens to jump between horizontal perches: effects of light intensity and perch colour

Abstract

Commercial non-cage housing systems for laying hens are kept at low light intensities to reduce the incidence of feather pecking. These low light intensity conditions may restrict the ability of hens to visually perceive important environmental features such as perches. This may have the potential to impair the movement of hens around the house and increase the risk of bird injury. These experiments evaluated the effect of light intensity, distance, and perch colour, on the ability of hens to jump between perches.In the first experiment, 60 laying hens were trained to jump from a start perch to a destination perch for a food reward. The performance of hens at this task was recorded under four different light intensities (0.8, 1.5, 6.0, 40lx) over distances of 1 and 0.5m. Time taken to complete the task (latency to jump) was recorded along with the behaviour of the bird whilst it remained on the start perch. The percentage of birds completing the task was lower at low light intensity. The latency to jump was significantly greater at lower light intensity (P<0.001), and greater when perches were positioned 1m apart compared to 50cm (P<0.001). The number of vocalisations performed was significantly higher at the low light intensities (P=0.002) and the greater distance of 1.0m (P<0.001).In the second experiment, 45 laying hens, trained in an identical way, were tested under three light intensities (0.6, 1.8 and 32lx) and three different destination perch colours (black, white and natural wood) over one distance of 0.75m. Once again, there was a significant effect of light intensity on the latency to jump between perches (P<0.001). Birds took less time to jump to white coloured perches compared to black coloured perches (P<0.001) and natural wood perches (P=0.028). The birds performed a greater number of vocalisations at low light intensities (P<0.001).The results suggest that very low light intensity conditions could restrict the movement of birds in non-cage systems. However, altering perch colour or making perches more visible to birds may be an effective solution to this problem and hence beneficial to bird welfare.