Plasma cortisol and faecal cortisol metabolites concentrations in stereotypic and non-stereotypic horses: do stereotypic horses cope better with poor environmental conditions?
1 Université Rennes 1 UMR CNRS 6552 Ethologie Animale et Humaine, Campus de Beaulieu bâtiment 25, 263 avenue Général Leclerc, Rennes Cedex, 35042, France
2 INRA, UMR1348 Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage, Saint-Gilles, 35590, France
3 Haras national de Sidi Thabet, Thabet, 2020, Tunisia
4 University of Veterinary Medicine, Department Natural Sciences Biochemistry, Veterinär-Platz 1, Vienna, A-1210, Austria
5 Current address: University of Guelph, Animal and Poultry Science department, Animal and Animal Behaviour and Welfare group, 50 Stone Road East, Building #70, Guelph, Ontario, N1G 2W1, Canada
BMC Veterinary Research 2013, 9:3 doi:10.1186/1746-6148-9-3Published: 7 January 2013
Stereotypic behaviours, i.e. repetitive behaviours induced by frustration, repeated attempts to cope and/or brain dysfunction, are intriguing as they occur in a variety of domestic and captive species without any clear adaptive function. Among the different hypotheses, the coping hypothesis predicts that stereotypic behaviours provide a way for animals in unfavourable environmental conditions to adjust. As such, they are expected to have a lower physiological stress level (glucocorticoids) than non-stereotypic animals. Attempts to link stereotypic behaviours with glucocorticoids however have yielded contradictory results. Here we investigated correlates of oral and motor stereotypic behaviours and glucocorticoid levels in two large samples of domestic horses (NStudy1 = 55, NStudy2 = 58), kept in sub-optimal conditions (e.g. confinement, social isolation), and already known to experience poor welfare states. Each horse was observed in its box using focal sampling (study 1) and instantaneous scan sampling (study 2). Plasma samples (collected in study 1) but also non-invasive faecal samples (collected in both studies) were retrieved in order to assess cortisol levels.
Results showed that 1) plasma cortisol and faecal cortisol metabolites concentrations did not differ between horses displaying stereotypic behaviours and non-stereotypic horses and 2) both oral and motor stereotypic behaviour levels did not predict plasma cortisol or faecal cortisol metabolites concentrations.
Cortisol measures, collected in two large samples of horses using both plasma sampling as well as faecal sampling (the latter method minimizing bias due to a non-invasive sampling procedure), therefore do not indicate that stereotypic horses cope better, at least in terms of adrenocortical activity.