Injurious pecking (IP) encompasses gentle and severe feather pecking and cannibalistic and vent pecking. Feather pecking causes plumage damage due to feather breakage and removal, while cannibalistic/vent pecking can result in injury and death. IP remains an important problem for the egg industry, particularly in loose housing systems, where it is difficult to control. It represents a welfare issue, as IP is painful for the pecked bird, and an economic issue due to an association with increased mortality and feed consumption, and decreased productivity. Many studies have examined the risk factors for IP (Rodenburg et al, 2013), both during the rearing and laying periods. Feather pecking in particular is thought to be redirected foraging behaviour: the risk of feather pecking is increased when ground pecking behaviour does not develop properly or is not adequately stimulated. Studies have shown litter materials which stimulate ground pecking behaviour can have protective effects against IP throughout life. In addition diet composition, form and management have all been identified as important factors. Diets low in protein and insoluble fibre have both been associated with an increased risk of IP, as has feeding a pelleted ration. Diet change appears to have a critical effect: each diet change at rear has been associated with a 62-fold increase in risk of IP (Gilani, 2012), and a similar association has been found during the laying period (Green et al, 2000).
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