Feather pecking genotype and phenotype affect behavioural responses of laying hens
Feather pecking (FP) is a major welfare and economic issue in the egg production industry. Behavioural characteristics, such as fearfulness, have been related to FP. However, it is unknown how divergent selection on FP affects fearfulness. Therefore, we compared responses of birds selected on low (LFP) and high feather pecking (HFP) with birds from a randomly selected control line (CON) to validated behavioural tests (i.e. novel object (NO), novel environment (NE), open field (OF) and tonic immobility (TI)) at young and adult ages. Furthermore, the relation between actual FP behaviour (i.e. FP phenotypes) and fearfulness is not well understood. Therefore, we compared responses of birds with differing phenotypes. Feather pecking phenotypes of individual birds were identified via FP observations at different ages. The number of severe feather pecks given and received was used to categorize birds as feather peckers, feather pecker-victims, victims or non-peckers. Here we show that HFP birds repeatedly had more active responses, which could indicate lower fearfulness, compared to CON and LFP birds at both young and adult ages. Within the HFP line, feather peckers had more active responses, suggesting lower fearfulness, compared to other phenotypes (especially feather pecker-victims and victims). Furthermore, feather pecker-victims and victims had more passive responses, suggesting higher fearfulness, compared to feather peckers and non-peckers. Thus, in this study high FP seems to be related to low fearfulness, which is opposite to what previously has been found in other experimental and commercial lines. This stresses the need for further research into the genetic and phenotypic correlations between FP and fearfulness in various populations of chickens, especially in commercial lines. Findings from experimental lines should be used with caution when developing control and/or prevention methods that are to be applied in commercial settings. Furthermore, activity and/or coping style might overrule fearfulness within the HFP line, as HFP birds and feather peckers within the HFP line had more active responses. This might indicate a complex interplay between fearfulness, activity and coping style that could play a role in the development of FP.