Glückliches Huhn: Ein reiches, lebenswertes Leben

Theoretical framework: There is a lack of operational approaches to assess the quality of life in animals. Methods for assessing cumulative lifetime experiences would provide objective means to study animals’ quality of life. Telomere dynamics (i.e. change in telomere length) might indicate the overall quality of an animal’s lifetime experience, including a range of aversive, neutral and even rewarding events. There is evidence from humans that telomere dynamics relate to life experiences. In non-human animals, telomere dynamics have been extensively studied in relation to negative experiences but the interactive effects of positive and negative experiences on telomere dynamics remain unexplored. Oxidative stress and elevated glucocorticoid levels are possible yet unconfirmed mechanisms of telomere dynamics.Hypotheses and objectives: Building on the finding that telomere shortening is accelerated in response to stress and slowed by improved stress resilience, we hypothesize that affective state will be linked to telomere dynamics. We will test this notion in chickens by investigating the effect on telomere dynamics of 1) experimentally and naturally elevated glucocorticoid levels and 2) enriched vs. barren housing conditions, which result in differences in stress resilience. We will also investigate the relationship between telomere dynamics and affective state directly, as a form of subjective interpretation of experiences.Methods: We will perform two studies to manipulate chickens’ quality of life: (1) we will manipulate chicken corticosterone levels (naturally with exposure to stressful vs. non-stressful conditions and artificially with corticosterone pellets); (2) we will house chickens either in enriched or in barren conditions and subject both groups to stressors. In both experiments, we will investigate the effect of treatment on telomere dynamics and the relationship between chicken affective state, faecal glucocorticoid metabolite levels, oxidative stress measures and telomere dynamics.Innovation: We will examine telomere dynamics as an indicator of cumulative lifetime experiences and provide novel knowledge on the interactive effects of positive and negative life experiences on telomere dynamics. For the first time, we will correlate affective state with telomere dynamics in chickens housed in a manner that allows them to gain different levels of positive experiences. In this way we will develop a much-needed tool to assess welfare.Primary researchers: The work will be undertaken by a PhD student, supported by three technicians and closely supervised by the applicant Dr Janja Sirovnik, with support from Dr Simon Verhulst for the analysis of telomere length, statistical analysis and interpretation of data.

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Zentrum für Tierernährung und Tierschutzwissenschaften