Biomarkers of happiness and stress in dairy cattle

PhD project by Louise Kremer. Animal welfare depends on their emotional experiences. Current methods to assess emotions in cows are still lacking validity. The aim of this project is to find an objective way to assess dairy cows’ emotions.

Dairy cattle welfare is a major societal issue. Farmers require valid and practical tools to monitor cattle welfare. Cattle affect is an inherent component of animal welfare reflecting the pleasant or unpleasant states of an animal. Affect involves changes in three inter-linked and measurable components: cognition, behaviour and physiology. While cognition and behaviour-based methodologies often face criticisms regarding their practicality and validity, promising physiological biomarkers of human affect have been found. I propose to identify physiological biomarkers of cattle affect in non-intrusive biofluids to constitute practical and valid metrics for cattle affect.

Three batches of 4 groups - 6 companion cows and 4 experimental heifers - will be tested. During a 'neutral' phase (8 weeks), groups will be housed under conventional conditions and their personality will be assessed using open-field and novel object tests. During a 'treatment phase', groups will be housed under increasing positive or negative conditions (6 weeks). Housing conditions, social stability and quality of the human-animal relationship will besuccessively improved or worsened in the positive and negative treatments, respectively. A judgment bias test, the best currently available method to assess animal affect based on the cognitive component of affect, will be designed for adult cattle to validate the treatment-induced affective contrasts.

Endocrine, immune and autonomic biomarkers of affect highlighted in other species will be measured and compared between treatments. Metabolomic studies, which allow simultaneous quantitative measurements of many metabolites in a biofluid, will further be applied. Metabolomics enable to broaden the search for biomarkers to potentially new indicators of affect. Physiological biomarkers varying between treatments will beconsidered as reliable biomarkers of cattle affect. Interactions between individual personality and cognitive, physiological and behavioural indicators of affect will finally be investigated, as personality has an important impact on affect at the individual level