Physical Health Problems and Environmental Challenges Influence Balancing Behaviour in Laying Hens

With rising public concern for animal welfare, many major food chains and restaurants are
changing their policies, strictly buying their eggs from non-cage producers. However, with
the additional space in these cage-free systems to perform natural behaviours and movements comes the risk of injury. We evaluated the ability to maintain balance in adult laying hens with health problems (footpad dermatitis, keel damage, poor wing feather cover; n = 15) using a series of environmental challenges and compared such abilities with those of
healthy birds (n = 5). Environmental challenges consisted of visual and spatial constraints,
created using a head mask, perch obstacles, and static and swaying perch states. We
hypothesized that perch movement, environmental challenges, and diminished physical
health would negatively impact perching performance demonstrated as balance (as measured
by time spent on perch and by number of falls of the perch) and would require more
exaggerated correctional movements.We measured perching stability whereby each bird
underwent eight 30-second trials on a static and swaying perch: with and without disrupted
vision (head mask), with and without space limitations (obstacles) and combinations
thereof. Video recordings (600 Hz) and a three-axis accelerometer/gyroscope (100 Hz)
were used to measure the number of jumps/falls, latencies to leave the perch, as well as
magnitude and direction of both linear and rotational balance-correcting movements. Laying
hens with and without physical health problems, in both challenged and unchallenged environments, managed to perch and remain off the ground. We attribute this capacity to our training of the birds. Environmental challenges and physical state had an effect on the use of accelerations and rotations to stabilize themselves on a perch. Birds with physical health problems performed a higher frequency of rotational corrections to keep the body centered over the perch, whereas, for both health categories, environmental challenges required more intense and variable movement corrections. Collectively, these results provide novel empirical support for the effectiveness of training, and highlight that overcrowding, visual constraints, and poor physical health all reduce perching performance.