Do double cages and access to occupational materials improve the welfare of farmed mink?
The effects of cage enrichments and additional space were studied in 60 pairs of mink kits kept in standard cages (STD) and 67 pairs of mink kits kept in enriched cages (ENR). During the period from mid July to the end of September both groups had alternate access to one and two connected
cages. From October, half of the mink in each group had permanent access to one cage and the other half permanent access to two cages. The enrichment of the cages consisted of extra resting places (tubes made of wire mesh and plastic) and occupational materials in terms of table-tennis balls
and ropes to pull and chew. The mink were observed for an experimental period of nine months, from late lactation until the beginning of the following mating season. The welfare was assessed through behavioural traits (use of nest box and enrichments, activity out in the cage, stereotypies
and fur-chewing) consumption of food and straw, bodyweight and level of faecal corticoid metabolites. The presence of enrichments resulted in less tail-chewing, fewer stereotypies, and a reduced level of faecal corticoid metabolites. In addition, the presence of enrichments led to fewer social
interactions and reduced the consumption of straw. Regarding the frequency of utilising different occupational materials, the mink did not use the table-tennis balls, but the tubes and pull-ropes were given extensive use. Access to one or double cages had no effect on stereotypies, fur-chewing
and physiology linked to welfare, but mink with access to double cages used the nest box less, had a lower consumption of straw and pull-ropes than the mink with access to only one cage. However, there were no indications of frustration when the mink were deprived of using double cages. We
conclude that increased environmental complexity in the form of occupational materials improved the welfare of the mink, whereas doubling the cage size had little or no effect in relation to mink welfare.