Hair cortisol levels in captive brown hare (Lepus europaeus): potential effect of sex, age, and breeding technology

Breeding wild animals for restocking imply their ability to respond to wild conditions and to overcome the stress of transport and cage rearing. Cortisol was used in animals to measure stress levels. Aims of the study were to ascertain if a difference in hair cortisol concentration (HCC) existed between hares raised according to different breeding technologies (familiar, semi-industrial, industrial breeding) before transportation and after a pre-acclimatization period, and if a short period of adaptation could reduce the stress status. Hair samples were collected from 120 hares from an area of approximately 13.5 sp cm from the left sulcus jugularis by using an electric hair clipper, at day 0 (d0) and after 15 days (d15), and processed by previously established procedures. HCC significantly decreased at d15 compared to d0 in all groups. A significant difference in HCC was detected between female hares of the three groups at d0, between male and female animals belonging to the industrial group at d15, between d0 and d15 in female hares belonging to the familiar and to the industrial group, and between d0 and d15 in male hares belonging to all groups. The different breeding technologies considered resulted exerting different stress levels in hares. Fifteen days of pre-acclimatization in a low-stress environment significantly reduced HCC. Controversial results have been obtained with female subjects from the industrial group, suggesting possible complex relationships between gender and HCC.