Life with a ball and chain

8 05 2014

Our giant OMAFRA-funded on-farm mink enrichment study, involving a total of 18 months’ data collection and c. 3200 animals, has just been submitted by Becky to PLoS One. At various points she and I thought this magnum opus would be the death of us, but we have finally wrestled it into submission!

Here is the abstract:


Benefits of a ball and chain: Simple environmental enrichments improve welfare and reproductive success in farmed American mink (Neovison vison)

Rebecca K. Meagher1,2, Jamie Ahloy Dallaire1, Dana L.M. Campbell1, Misha Buob1, Steffen W. Hansen3, María Díez-León1, Rupert Palme4, Georgia J. Mason1*

1 Department of Animal and Poultry Science, University of Guelph, 50 Stone Rd. E., Building 70, Guelph, ON, Canada N1G 2W1
2 Animal Welfare Program, Faculty of Land and Food systems, University of British Columbia, Vancouver, Canada V6T 1Z4
3 Department of Animal Science, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark
4 Department of Biomedical Sciences/Biochemistry, University of Veterinary Medicine, Veterinärplatz 1, A-1210, Vienna, Austria
* Corresponding author: gmason@uoguelph.ca

Can simple enrichments enhance caged mink welfare? A pilot study of 756 sub-adults spanning three colour-types (breeds) identified potentially practical enrichments, and suggested beneficial effects on temperament and fur-chewing. Our main experiment started with 2032 Black mink on three farms: from each of 508 families, one juvenile male-female pair was enriched (E) with two balls and a moveable hanging plastic chain or length of hose, while a second male-female pair was left as a non-enriched (NE) control. At 8 months, over 50% subjects were killed for pelts, and so 302 new females were recruited (half enriched: ‘late E’). Several signs of improved welfare emerged. Access to enrichment increased play in juveniles. E mink were calmer (less aggressive in temperament tests; quieter when handled; less fearful, if male), and less likely to fur-chew, although other stereotypic behaviours were not reduced. On one farm, E females had lower cortisol (inferred from faecal metabolites). E males copulated for longer, and E females weaned more offspring: about 10% more juveniles were produced per E female, primarily caused by reduced rates of barrenness (‘late E’ females also gave birth to bigger litters on one farm), effects that our data cautiously suggest were partly mediated by reduced inactivity and changes in temperament. Pelt quality seemed unaffected, but E animals had cleaner cages. In a subsidiary side-study using 368 mink of a second colour-type (‘Demis’), similar temperament effects emerged, and while E did not reduce fur-chewing or improve reproductive success in this colour-type, E animals were judged to have better pelts. Overall, simple enrichments were thus beneficial. These findings should encourage welfare improvements on fur farms (which house 60-70 million mink p.a.) and in breeding centres where endangered mustelids (e.g. black-footed ferrets) often reproduce poorly, as well as stimulate future research into more effective practical enrichments.


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