The social transmission of feather pecking in laying hens: effects of environment and age

Abnormal behaviours, such as feather pecking, can become an even greater problem if they spread through the flock. Domestic hens are a social species and it has been suggested that feather pecking behaviour can be socially transmitted from few feather pecking individuals to many. The purpose of this experiment was to investigate whether feather pecking is transmitted from an experimental strain of high feather peckers to an experimental strain of low feather peckers when housed together. The effects of environment and age were also investigated. Four hundred and twenty chicks were housed in either cages or pens in one of three treatment groups; all high feather peckers, all low feather peckers, and a mixed group of half high feather peckers and half low feather peckers. During the rearing phase, severe and gentle feather pecks were recorded at 13–15 weeks and feather plumage scored at 12 and 17 weeks. At 17 weeks of age, the groups of mixed hens were removed from the study and the remaining hens resorted into the same three treatment groups. During the laying phase, severe and gentle feather pecks were recorded at 30–32 weeks of age and feather plumage was scored at 29 weeks of age. There was significantly less feather pecking and plumage damage in the pens than in the cages. There was no evidence of severe feather pecking spreading from feather peckers to non-feather peckers, even when actual rates of feather pecking were examined rather than only considering the strain of hen. There was some evidence that gentle feather pecking was transmitted in laying hens housed in cages. However, as gentle feather pecking does not lead to plumage damage, this is less relevant to commercial practice.