The genetics of feather pecking and cannibalism

Feather pecking and cannibalism are important welfare issues in the battery cage system and even more of a problem in alternative systems of egg production. Interest in the genetics of feather pecking and cannibalism has grown in the last few decades and a genetic solution might be more sustainable, efficacious and cost-effective than environmental modifications. Strain differences in the plumage condition of laying hens and feather pecking behaviour have been reported. More recently within-line genetic components of feather pecking and cannibalism have been quantified. Estimates of the heritability of plumage condition range from moderate (0.22) to high (0.54) and the heritability of observations of pecking behaviour from 0.06 to 0.38. Some selection experiments have produced little or no evidence of a response. However, in one experiment, group selection was very effective in reducing the incidence of beak-inflicted injuries in caged hens and realized family heritability was 0.65 +/- 0.13. Divergent selection for high and low feather pecking resulted in significant differences in feather pecking behaviour and plumage condition. There is uncertainty about the correlated responses to selection for low feather pecking and cannibalism, and this justifies more research. Molecular approaches may offer the opportunity for selection to decrease feather pecking and cannibalism without compromising the welfare of birds in the selected flock. However, the evidence so far is not encouraging, and future opportunities to change the propensity for damaging feather pecking and cannibalism in commercial laying hens will probably rely on conventional selection in appropriate environments.