Running in a running wheel substitutes for stereotypies in mink (Mustela vison) but does it improve their welfare?

This experiment investigated whether access to a running wheel affects the development of stereotypies during restricted feeding and whether selection for high or low levels of stereotypy affects the use of the running wheel. Sixty-two female mink kept in standard cages and selected for high or low levels of stereotypy were used. Thirty of these females had access to a running wheel whereas thirty-two female mink had no access to running wheels. The number of turns of the running wheel, behaviour, feed consumption, body weight and the concentration of plasma cortisol were measured during the winter period. Mink with access to a running wheel did not perform stereotypic behaviour and mink selected for a high level of stereotypies had more turns in the running wheel than mink selected for low levels of stereotypies. Mink with access to a running wheel used the running wheel for the same amount of time as mink without access to a running wheel performed stereotypies, and the daily rhythms of the two types of activity were identical with a peak around feeding time. No other behavioural differences between stereotyping and non-stereotyping mink were found and neither was there any difference in plasma cortisol. Due to the similarities between stereotypies and wheel running it is not possible unambiguously to conclude that access to a running wheel improve the welfare of the mink.