Brown and white layer pullet hybrids show different fear responses towards humans, but what role does light during incubation play in that?
Manet, Maëva; Kliphuis, Saskia; Nordquist, Rebecca; Goerlich, Vivian; Tuyttens, Frank A.M.; Rodenburg, Bas
(2023) Applied Animal Behaviour Science, volume 267
(Article)
Abstract
Good early life conditions are increasingly recognized as essential to animal welfare later in life. The use of light during incubation might improve coping capacities and welfare in later life in poultry, by more closely approximating chicken natural environments compared to the current conventional incubation in darkness. Previous studies showed
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that lighted incubation resulted in more lateralized chicks, a more pronounced daily behavior rhythm, earlier onset of melatonin rhythms, and lower stress reactions to various stressors after hatching. Most existing research, however, has been conducted on broilers, and little information on lighted incubation is available for laying hens. In the current research, Dekalb White and ISA Brown eggs were incubated in complete darkness or in a cycle of green 12 L:12D throughout incubation, and five fear of human tests were performed on the 387 chickens during the rearing phase. We expected dark-incubated chickens to show stronger fear responses than light-incubated chickens. That was only the case for one of 15 behavior measurements taken during the tests (p < 0.05). In addition, white layer hybrids are known to be flightier and more fearful than brown hybrids. In this study, white chickens indeed showed stronger fear responses than brown chickens in 12 of the 15 behavior measurements (p ≤ 0.002). Furthermore, we expected light during incubation to have stronger effects on white chickens than on brown chickens, because of the stronger transmission of light through white eggshells. However, the interaction between hybrid and incubation was never significant (p ≥ 0.18). Finally, contrary to our expectations, there was no effect of the incubation treatments or the hybrid on plasma corticosterone responses to a manual restraint test (p ≥ 0.36). Since there was a hybrid effect on behavior in this test, it is reasonable to think that behavior reflected coping style, rather than fear level. To conclude, the light regime used in this study does not seem as promising as expected to improve laying hen welfare. Finally, the brown hybrid was usually less fearful than the white hybrid, though there were some exceptions depending on the stressor, and that should be taken into account in research and in laying hen management.
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Keywords: Chicken, Prenatal, Fear behavior, Corticosterone, Welfare, Animal-human interaction
ISSN: 0168-1591
Publisher: Elsevier
Note: Funding Information: This project received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812777. This document reflects only the authors’ view and the European Union's Horizon 2020 research and innovation program is not responsible for any use that may be made of the information it contains. The authors thank Susanne Kirchhoff for performing the lab work on the blood samples, and Jary Weerheijm for assisting her. The authors are grateful to the colleagues and students who helped collecting the behavior data and/or the blood samples (in alphabetical order): Serge Alindekon, Dewi Bouman, Inge van der Burg, Casper van Eekelen, Dylan Geerman, Marjolein Jongerius, Elsemieke van der Laan, Dr Esther Langen, Zinzhi van Leeuwen, Lisette Martens, Britta Mescher, Arjen van Putten, Eric Scherpenisse, Isabelle Spierings, Marije Spinder, Annika Stokvis, Lisa Veldkamp, Marenne Vis, Jary Weerheijm and Claudia van der Zijden. Funding Information: This project received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 812777 . This document reflects only the authors’ view and the European Union’s Horizon 2020 research and innovation program is not responsible for any use that may be made of the information it contains. Publisher Copyright: © 2023 The Authors
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