Using cameras to record walking ability in broiler chickens

The results of the study contribute to making automated scoring of broiler walking ability more feasible in practice and were recently published in Poultry Science.

Impaired walking ability can negatively impact the welfare of broilers, but is currently challenging to record on a large scale. Commonly, walking ability, or gait, is scored manually, which is time consuming, subjective, and requires extensive training. Automation of gait scoring can help to make this process faster and more
objective, and thus make phenotyping for walking ability more feasible on a
larger scale. In earlier work, walking characteristics of broilers were recorded automatically, using back-view videos of broilers walking in a corridor. It was observed that there were differences in hock joint lateral angles, hock-feet distance ratios and relative step height between broilers with good versus suboptimal gait. However, back-view videos of broilers for gait assessment are challenging to obtain under practical conditions, where birds may occlude each other. Therefore, top-view videos might be more suitable for practical conditions.

Characterizing walking ability from top-view videos

The researchers collected top-view videos of broilers walking one by one in a corridor-like walkway, within the public private partnership project Automated Broiler Phenotyping. Using computer vision and object detection techniques, the broilers were identified and tracked in the videos to extract walking characteristics of the broilers. These walking characteristics included the birds’ lateral body oscillation, which is the swinging of the centre of the body from left to right and vice versa during walking, the number of steps taken to complete the walkway, and the time it took for the birds to complete the walkway. Subsequently, it was studied whether and how these walking characteristics correlate with manually determined gait scores and severity of contact dermatitis (foot pad dermatitis, hock burn).

Differences in walking characteristics between birds with different gait scores

“We observed that birds with worse gait scores had longer walkway completion times, took more steps to complete the walkway, and showed a tendency for higher lateral body oscillation levels, indicating more swinging during walking,” says István Fodor, researcher at ABG. “Furthermore, we found that an unsupervised clustering method could distinguish birds with poor gait scores from birds with better gait scores, but it was challenging to distinguish between birds with good versus moderate gait scores.”

Top-view walking characteristics are less informative for contact dermatitis

The researchers also examined whether the top-view features differed between birds with no or mild cases of contact dermatitis. No relationships were observed between the top-view features and hock burn or foot pad dermatitis, indicating that prediction of contact dermatitis is not feasible with the current top-view features.

Next steps

Overall, the results of this study show that top-view derived walking characteristics are informative for broiler walking ability and mark a step forward towards automated gait scoring in the future. In the coming months, the researchers will continue to work on this topic, to identify and measure even more walking features from the top-view videos, in order to capture more subtle differences in walking ability.