A Novel Model to Explain Extreme Feather Pecking Behavior in Laying Hens

Area of Science:

• Animal Science
• Genetics
• Animal Welfare

Background:

• Feather pecking (FP) is a significant welfare and economic issue in domestic fowl.
• FP behavior is not uniformly distributed, with a distinct sub-population of extreme feather peckers (EFP).

Purpose of the Study:

• To develop and validate a novel model for detecting EFP hens.
• To investigate the genetic basis and fear-related correlates of EFP behavior.

Main Methods:

• Fitted a mixture of two negative binomial distributions to FP data from 960 F2 cross hens.
• Calculated posterior probabilities (pEFP) for hens belonging to the EFP subgroup.
• Conducted tonic immobility and emerge box tests to assess fearfulness, followed by multivariate threshold model analysis and a genome-wide association study (GWAS).

Main Results:

• The EFP subgroup constituted one-third of the F2 population.
• EFP birds exhibited increased frequency and intensity of pecking compared to non-EFP birds.
• The pEFP trait showed medium heritability (0.35) and a positive correlation with fear traits; GWAS indicated a polygenic basis for all studied traits.

Conclusions:

• The developed model effectively identifies EFP hens, characterized by higher pecking propensity and fearfulness.
• Breeding programs targeting pEFP or fear-related traits could be a viable strategy to mitigate extreme feather pecking in poultry.
• Genome-wide association studies confirm that feather pecking and associated fear traits are complex quantitative traits influenced by numerous genes with small effects.