Stereotypic Beha Viour and Tail Biting in Farmed Mink (Mustela Vison) in a New Housing System
Farmed mink are known for showing stereotypies and tail biting, behaviours that are mostly viewed as indicators of reduced welfare. Among the factors that are often described as being relevant for the welfare of mink are food management systems, age at weaning, and type/presence of
nest boxes and bedding. In the present study of commercially farmed mink, all of these factors have been integrated in one housing system. The occurrence of stereotypies and tail biting were observed at six Dutch mink farms, which differed from one another with respect to the number of modifications
and the time since the introduction of these modifications. On each farm, 60 non-lactating female mink were observed during winter and 50 lactating female mink (with kits) were observed during summer. Mink on the farm with the most modifications spent 4.1% and 0.8% of their time performing
stereotypies in winter and in summer, respectively. Mink on the farm with the least modifications spent 32% and 10.9% of their time performing stereotypies in winter and in summer, respectively. The occurrence of stereotypic behaviour in winter gradually increased as feeding time approached.
This gradual increase was not observed at the farm with the least modifications. In general, mink spent less time performing stereotypies in summer than in winter. No clear differences were found between the farms for the occurrence of tail biting in relation to the modifications of the new
system, although one farm showed a lower percentage (4%) of tail biters during summer. In conclusion, the farms that had introduced more modifications into their husbandry system housed animals showing less stereotypic behaviour. The results of this field study demonstrate an inverse relationship
between the number of modifications and the occurrence of stereotypies; because of the experimental design, however, a causal relationship is not implied. Further work is required to investigate the impact of each measure both in isolation and in the integrated system under more carefully