Meeting Abstract
Broiler chicken production continues to increase rapidly worldwide. However, genetic success for desired production traits has come at a trade-off with increased concerns over musculoskeletal health. One perceived concern is that the chickens’ walking capacity decreases as they age – likely caused by a rapid growth rate and large increase in breast muscle mass. However, quantitative methods for assessing chicken walking capability remain limited. Recent experimental and theoretical studies of similar sized birds (e.g., pheasants, guinea fowl) have found “leg loading angle (β)” to be a critical locomotor parameter. This angle, defined as the difference between the leg angle and the body velocity vector at footstrike, has a strong correlation with leg loading and leg work, factors relevant to both economy and leg injury risk. The aim of this study was to quantify broiler chicken walking ability by investigating changes in β over ontogeny. We hypothesized that, consistent with a perceived reduction in broiler walking ability, the mean and standard deviation of β would increase as chickens age. Ten (10) birds from three age groups (2, 4 and 6 weeks) were encouraged to walk across a platform while collecting marker data using 8 Qualisys cameras. At least 10 trials were collected per bird, generating a dataset with ~1,000 steps per group. Step data were binned by walking speed and mean and standard deviations (SD) calculated for β at each speed and age group. In all age groups average β values were similar to those previously found for pheasants (45-55 degrees versus 50 degrees, respectively). However, SD of β for level running was consistently higher for 4 and 6 week old chickens compared to pheasants (5 versus ~10 degrees, respectively). The inability of broiler chickens to tightly regulate leg loading angle may indicate reduced walking stability and economy.
