Tag: Genetics

Stress response, peripheral serotonin and natural antibodies in feather pecking genotypes and phenotypes and their relation with coping style. By Jerine A.J. van der Eijk, Aart Lammers, Joergen B. Kjaer, T. Bas Rodenburg. 2019. Physiology & Behavior 199: 1-10.

Highlights

• Physiological & behavioral measures were studied in relation to feather pecking (FP).

• Stress response, natural antibody titers, corticosterone & 5-HT level were identified.

• FP genotypes differed in behavioral responses, 5-HT level & natural antibody titers.

• FP phenotypes differed in behavioral responses & 5-HT level.

• FP genotypes and FP phenotypes could not be categorized into coping styles.

Abstract

Feather pecking (FP), a serious welfare and economic issue in the egg production industry, has been related to coping style. Proactive and reactive coping styles differ in, among others, the stress response, serotonergic activity and immune activity. Yet, it is unknown whether genetic lines divergently selected on FP (i.e. FP genotypes) or individuals differing in FP (i.e. FP phenotypes) can be categorized into coping styles. Therefore, we determined peripheral serotonin (5-HT) levels, natural antibody (NAb) titers, behavioral and corticosterone (CORT) responses to manual restraint (MR) in FP genotypes (high FP (HFP), low FP (LFP) and unselected control (CON) line) and FP phenotypes (feather pecker, feather pecker-victim, victim and neutral). We further examined the consistency of and relationships between behavioral and physiological measures. FP genotypes differed in behavioral responses to MR, 5-HT levels and NAb titers, but not in CORT levels after MR. HFP birds had less active responses at adolescent age, but more active responses at adult age compared to LFP and CON birds. The CON line had higher 5-HT levels at adolescent age, while the HFP line had lower 5-HT levels than the other lines at adult age. Overall, the HFP line had lower IgM NAb titers, while the LFP line had lower IgG NAb titers compared to the other lines. FP phenotypes differed in behavioral responses to MR and 5-HT levels, but not in CORT levels after MR or NAb titers. Within the HFP line, feather peckers tended to have less active responses compared to neutrals at adolescent age, while victims had more active responses compared to the other phenotypes at adult age. Feather peckers had higher 5-HT levels than neutrals at adult age. Behavioral and CORT responses to MR were not consistent over time, suggesting that responses to MR might not reflect coping style in this study. Furthermore, proactive behavioral responses were correlated with reactive physiological measures and vice versa. Thus, it was not possible to categorize FP genotypes or FP phenotypes into specific coping styles.

Feather pecking genotype and phenotype affect behavioural responses of laying hens By Jerine A.J. van der Eijk, Aart Lammers, Peiyun Li, Joergen B. Kjaer, T. Bas Rodenburg, 2018. Applied Animal Behaviour Science 205: 141-150

Abstract 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 in comparison to no selection on FP. Therefore, we compared responses of birds selected on low (LFP) and high feather pecking (HFP) with birds from an unselected control line (CON) to several 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 FP phenotypes. Feather pecking phenotypes of individual birds were identified via FP observations at several ages. The number of severe feather pecks given and received was used to categorize birds as feather peckers, feather pecker-victims, victims or neutrals. Here we show that HFP birds repeatedly had more active responses (i.e. they approached a NO sooner, vocalized sooner and more, showed more flight attempts and had shorter TI durations), 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 (i.e. they tended to show more flight attempts compared to victims and tended to walk more compared to neutrals), suggesting lower fearfulness, compared to victims and neutrals. 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.

Highlights

• The effect of feather pecking genotype and phenotype on fearfulness was studied.

• Responses of birds to behavioural tests were studied at young and adult ages.

• High feather pecking line had more active responses, suggesting lower fearfulness.

• Feather peckers had more active responses, suggesting lower fearfulness.