Brave breeds and brains under the spotlight how do light during incubation and genetics impact young laying hens stress responsivity?

Maëva Manet*, Saskia Kliphuis, Rebecca Nordquist, Vivian Goerlich, Frank A.M. Tuyttens, Bas Rodenburg

*Corresponding author for this work

Research output: Contribution to conferencePosterAcademic

Abstract

A promising intervention to improve chicken welfare is the presence of light during incubation. More specifically, a cycle alternating a phase of green light and a phase of darkness has proved to help decreasing fearfulness in broilers. The impact on laying hens, however, is not known. We thus investigated the effects of light during incubation on the stress sensitivity of two common layer hybrids: ISA Brown and Dekalb White. The latter are known to be flightier than the former, especially with humans. Although the developmental stage has a major impact on the ability to cope with stressors at adulthood, there is an even greater gap of knowledge on the impact of light during incubation on layer pullets. That led the rearing phase to be the main focus of our research. Half of the eggs of each hybrid were incubated in standard dark conditions and the other half in a green light:dark cycle of 12:12 throughout the incubation, resulting in a 2*2 design. Different behaviour tests were performed to investigate pullets stress responsivity, including two novel object tests and two voluntary approach tests. We expected the light-incubated chicks to show lower fear responses in both tests as compared to dark-incubated chicks. In addition, we expected brown chicks to show lower fear responses in the voluntary approach tests as compared to white chicks. Finally, stronger effects of the incubation treatment were expected in the white chicks – given their higher stress sensitivity and a better transmission of light through white eggshells compared to brown. There was a tendency to have more light-incubated chicks close to the first novel object at the same time (N = 20, linear mixed-effects model, p = 0.088), which would indeed show that these chicks are less fearful than the dark-incubated ones. A second round of experiments is required to increase the sample size and confirm these results. Brown pullets pecked at the bait significantly faster than the white ones during both the voluntary approach tests (N = 188, Cox model survival analysis, p < 1,84e-05), meeting our expectations to be less fearful. However, light during incubation only tended to make the pullets less fearful (p = 0.0981), and there was no interaction between the two factors. Human-chicken interactions being very relevant in practice, this shows the importance of adapting the farming conditions to the hybrid used, rather than looking for a universal solution to improve laying hen welfare.
Original languageEnglish
Publication statusPublished - 17 Jun 2021
EventRecent advances in welfare science VIII (UFAW) -
Duration: 29 Jun 202130 Jun 2021

Conference

ConferenceRecent advances in welfare science VIII (UFAW)
Period29/06/2130/06/21

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