Chicken genomics: feather-pecking and victim pigmentation

Area of Science:

• Animal Behavior
• Genetics
• Animal Welfare

Background:

• Feather-pecking is a serious welfare concern in domestic birds, often leading to cannibalism.
• The evolution of feather-pecking, a spiteful behavior with no direct benefit to the aggressor, remains unexplained.
• Plumage characteristics may influence a bird's susceptibility to feather-pecking.

Purpose of the Study:

• To investigate the genetic and environmental factors predisposing domestic birds to feather-pecking.
• To understand the role of plumage pigmentation and allele frequency in feather-pecking victimisation.
• To explore the evolutionary origins of feather-pecking during domestication.

Main Methods:

• An intercross experiment was conducted between a domestic fowl and its wild ancestor.
• The study analyzed the association between plumage color (controlled by the PMEL17 gene) and feather-pecking incidence.
• The frequency of specific plumage alleles within flocks was assessed in relation to victimisation rates.

Main Results:

• Birds expressing a wild recessive allele at the PMEL17 gene, affecting melanization, were more likely to be victims of feather-pecking.
• The commonness of these specific plumage types within a flock increased the likelihood of individual birds becoming victims.
• Genetic predisposition related to plumage color significantly influences feather-pecking susceptibility.

Conclusions:

• Plumage pigmentation, specifically due to certain recessive alleles affecting melanization, predisposes chickens to feather-pecking.
• The prevalence of these genetic traits within a population exacerbates the welfare problem.
• These findings offer insights into the genetic underpinnings of feather-pecking evolution during domestication and highlight welfare implications.