An objective approach to understand effects of keel bone fracture on the welfare of laying hens and providing solutions to reduce their occurrence and severity

Principal Investigator: Michael Toscano
Project Team: Hanno Würbel (official supervisor)
Ariane Stratmann (PostDoc)
Christina Rufener (PhD student)
Collaborator: Lars Schrader (Friedrich-Loeffler Institut Celle)
Alexandra Harlander (University of Guelph)
Bret Tobalske (The University of Montana)
Funded by: Swiss Federal Food Safety Veterinary Office (FSVO)

Although up to 80 % of laying hens worldwide are affected by keel bone damage, its cause and the full extent of the impact on the welfare of hens is not yet fully understood. Besides feeding and breeding related aspects, the housing system also influences the occurrence and severity of fractures.  Although aviaries appear to provide many benefits to hens including ability to perform natural behaviours, their height and complexity likely increases the risk of crashes and collisions which is why investigation is needed to assess animal welfare. Therefore, this study investigates the link between keel bone damage and animal welfare of laying hens housed in aviaries. The aim of the project is to assess the effect of keel bone damage on the mobility within the housing environment and productivity. Alteration of natural behaviour and biological functioning in response to injury is  evidence for the inadequacy of the respective housing system. A decrease in productivity and therefore fertility is another expression of stress leading to impaired welfare. Since the hens will be observed individually for a whole production period under commercial conditions, the healing process as well as adaptations in behavior patterns and variations in productivity can be described.

The second phase of the project will investigate different configurations (height, distance, angle, material, shape, …) of perches or other aviary elements. Aspects like wing motion and the impact on the keel bone during the landing will be observed to determine the role that locomotion from / to perches plays in causing fractures while providing information that can be incorporated into aviary systems and reduce fractures sustainably.