Barren housing and negative handling decrease the exploratory approach in farmed mink

Abstract

We examined the influence of cage enrichment and different types of short-term experiences on the temperament of farmed mink. We used juvenile Palomino mink (n = 600, housed in pairs of one male and one female) in a two-factor design with cage environment (BAR: barren vs. ENR: cage enriched with a shelf and a tube throughout) and exposure to one type of short-term experience (Negative: caught and kept in a small trapping cage for 15 min, Neutral: no treatment, and Positive: provision of canned cat food treat). The test-naïve mink were evaluated for curiosity and fearfulness in a voluntary approach-avoidance test (stick test) in their home cage after 4 weeks of housing treatment (BAR vs. ENR) on the day following the short-term experience. Both the housing and the type of short-term experience, with no interaction between them, influenced the proportion of mink scored explorative in the first stick test. Mink in the ENR cages were more curious, as they had a shorter latency to exploratory contact (P < 0.001), and a larger proportion were scored explorative (30.1 %) than mink housed in BAR cages (17.4 %; P < 0.001). The type of short-term experience affected females, but not males. Female mink exposed to the negative event were scored less explorative and kept a longer distance (42 ±2.5 cm) during the test than did mink exposed to no (31 ±2.4 cm) or the positive (28 ±2.1 cm) event (P < 0.001). We re-tested all mink 3 weeks later, after the grading of the winter fur, which is a handling procedure conducted yearly during the late part of the production year on commercial farms. The distance to the stick increased on average 27 % after this fur grading procedure. BAR mink were more sensitive than ENR mink, as they increased the distance more after the fur grading procedure (BAR: 12 ±1.2 cm vs. ENR: 5 ±1.7 cm, P < 0.001). Further, the BAR mink shifted towards a more fearful temperament score than ENR mink after the fur grading procedure. In conclusion, exposure to a negative handling experience increased avoidance and reduced the number of exploratory female mink. Thereby, negative handling and cage bareness pose a risk for increasing the proportion of fearful mink on farms. In contrast, relatively simple cage enrichments to mink may increase on-farm welfare via a shift from fearfulness towards more curiosity.