Selection against stereotypic behaviour may have contradictory consequences for the welfare of farm mink (Mustela vison)

The present study aimed to examine if divergent selection for stereotypic behaviour in mink influences the welfare of the animals. Two breeding lines were used, a high stereotyping line (HSL, N = 139) and a low stereotyping line (LSL, N = 132). Their welfare was assessed on the basis of adrenocortical activity (faecal cortisol metabolites, FCM), confident versus fearful temperament, growth and reproduction. The results showed that the LSL performed less stereotypic behaviour and were less active than the HSL. Furthermore, the results demonstrated that: (1) the LSL had lower concentrations of FCM, indicative of better welfare; (2) there was no clear difference in temperament between the lines, however, within the HSL a positive correlation was found between the frequency of stereotypy and the frequency of confident temperament; (3) there was no difference in reproduction; (4) there was no failure to grow in any line, but on average the body weight in the LSL was higher than that in the HSL. The correlation between stereotypy and confidence in the present study supports earlier findings showing a higher proportion of fearful animals in groups of low stereotyping mink. So, although the selection against stereotypic behaviour clearly reduced the FCM it may have contradictory consequences for the welfare of the mink.