The effect of Keel Bone Fractures on the Welfare of Free-range Laying Hens and an Alteration in the Belief that providing Aerial Perches increases the Risk of these Fractures

Fractures of the keel bone in laying hens occur frequently within free-range systems and are a significant welfare concern. As poultry farmers have increasingly adopted this type of housing, it becomes more urgent to address the problem of such fractures. More than 80% of free-range birds could be affected, compared to 36% of birds in furnished-cage systems (Wilkins et al., 2011). A hen’s ability to roam, fly and jump within a free-range environment provides greater opportunity for the anatomically vulnerable keel bone to contact objects with more force than can occur within the confines of a cage (Vits et al., 2005). It has been suggested that falling from or colliding with aerial perches may cause keel bone fractures (Gregory et al., 1990, in Donaldson et al., 2012a & b). In recent years, the effects of providing aerial perches has been specifically studied, along with the impact keel bone fractures have on the behaviour of laying hens, and thus on welfare.