Many egg layers experience keel bone fractures at some point in their lives. This is true for hens on the floor in deep litter and battery hens in conventional systems as well as free-range and organic egg layers with access to outdoor areas. 

Fractures may arise because of collisions with housing structures or other hens, or because of failed landings but for most of the injuries the underlying reason is unknown. 

The Ministry of Environment and Food of Denmark asked Aarhus University to review current knowledge about the relation between keel bone fractures and egg layer welfare. In a recent review, researchers from the Department of Animal Science conclude that the injuries constitute a welfare problem, irrespective of which animal welfare concern is applied. The results have been published in the scientific journal Frontiers in Veterinary Science. 

- While studying how keel bone fractures affect hen welfare, we included different animal welfare concerns. We conclude that keel bone fractures constitute a welfare problem, irrespective of the applied welfare concern as the injuries affect production, the hens’ ability to display natural behavior and the opportunity for a life without pain, says Senior Researcher Anja Brinch Riber, Department of Animal Science, Aarhus University. 

Keel bone fractures result in fewer eggs

Layers with keel bone fractures produce fewer eggs, and more studies indicate that they are experiencing pain. 

- In behavioural tests, egg layers with keel bone fractures have been shown to be reluctant to jump from their perches to achieve a mealworm treat. In addition, the injuries impair the natural behavior of the hens. The birds have been shown to spend less time sleeping on the perches. Instead, they rest more on the floor, which is not normal behavior, says Anja Brinch Riber. 

Policy advice in a scientific journal

The study of the relation between keel bone fractures and animal welfare was commissioned by the Ministry of Environment and Food of Denmark as part of the agreement with Aarhus University on the provision of research-based policy advice. 

- In assignments like this, we have answered the questions from the authorities by providing them with a survey of the existing knowledge within the area. The fact that the article was published in Frontiers in Veterinary Science allowed us to communicate this knowledge to the benefit of everyone, says Anja Brinch Riber. 

The reason underlying keel bone fractures remains ambiguous, but breeding for production and feed efficiency probably plays a certain role, as the modern hen has small breast muscles, a low body weight and produces many eggs from an early age. Further research is needed to learn more about the causes of this welfare problem as well as how to prevent it. 

Read the article “The Influence of Keel Bone Damage on Welfare of Laying Hens” in Frontiers in Veterinary Science here. 

For further information please contact: Senior Researcher Anja Brinch Riber, Department of Animal Science, e-mail: anja.riber@anis.au.dk, telephone: +45 8715 7949