Severe feather-pecking in non-cage laying hens and some associated and predisposing factors: a review

Severe feather-pecking (SFP), whereby birds vigorously peck at and pull out the feathers of conspecifics, is an extremely injurious, highly prevalent behaviour. It has acute negative impacts on the egg industry worldwide, in terms of both animal welfare and production efficiency. A large volume of research has been conducted to investigate the underlying causes. However, although many contributing factors have been identified, it remains largely unpredictable, and very difficult to control. Environmental influences during the rearing period, feeding behaviour, feather-eating and individual bird differences play important roles in the expression of SFP. This paper provides a review of some of the literature on the aforementioned causes of SFP in laying hens.