Anticipatory activity and stereotypical behaviour in American mink (Mustela vison) in three housing systems differing in the amount of enrichments

The present study aimed to measure anticipatory activity in farmed mink (Mustela vison) to study the effects of the presence of environmental enrichments in three housing systems differing in cage structure and in the amount of enrichments. In studies on laboratory rats, anticipatory activity is used as a parameter for potentially stressful conditions of different housing systems: enriched housed rats were less sensitive to sucrose-rewards than standard housed rats as shown by a lower anticipatory reactivity suggesting less stressful conditions. Anticipatory activity in 36 adult female mink was elicited in a Pavlovian paradigm with tasty cat food as reward in January 2002. This Pavlovian paradigm was followed by an observation of stereotypical behaviour in February 2002. The Pavlovian paradigm and the observations of stereotypical behaviour were preceded by observations on juvenile mink behaviour (7¿11 weeks of age) in the Summer of 2001. The results of this study show (1) that mink juveniles in the most enriched system had more variable behaviour suggesting better coping potentials and (2) that mink, just like rats, can be trained to anticipate on reward. However, in contrast to the behavioural results of the juveniles, no significant long-term effects of the additional enrichments were found as measured by anticipatory activity and stereotypical behaviour, suggesting no differences between the experimental housing systems in terms of stress.