End of an era

20 06 2015

Eight years ago, thanks to the willingness of our great MSU collaborators Steve Bursian and Angelo NapolitanoMaria constructed 32 fabulous enriched liHouse 10 in its gloryving quarters for mink, interspersed with 32 regular cages. All animals had the same home cage (seen at the left of the photo), but half the cages also provided access to large enriched compartments — each large enough to fit a prone Jamie — reached by a series of ramps and overhead wire mesh bridges.  Each enriched cage contained a trough of circulating water (the black channel in the pictures; pumped and filtered using aquaculture equipment), for mink to splash and wade in. Enriched mink also often had an extra next box, squeaky toys, dangling objects to chew, shoes, hammocks, and a variety of other things to destroy or sleep in/under. We’ve raised/housed several (five?) batches of mink in these cages since Maria first built them.

Jamie sleeping in EE cage

As planned, the enrichments were always very effective at reducing stress and abnormal behaviour (e.g. Dallaire et al. 2012 AABS, Diez-Leon et al. 2013 PLoS One). But the particular way we designed the set-up also had several other advantages from a research perspective. It made it easy to assess the time animals spent with enrichments (the mink spending significantly more time in enriched compartments than you’d expect by chance [Diez-Leon et al. under revision for AABS], with usage also being both variable across and stable within individuals [Dallaire et al. 2012 AABS, Diez-Leon et al. under revision for AABS]). It was also easy to see qualitative differences in enrichment-use; for example mink who were highly stereotypic in standard cages liked to rest in the tunnels far more than other individuals (Dallaire et al. 2012 AABS)

We could also ask mink to pay for enrichment-access, by placing weighted one-way doors in the tunnels (the av. max. weight pushed before giving up turned out to be 1.4 kg: NS different from what mink would push for food [Dallaire et al. 2012 AABS]). We could also lock enriched mink into the standard cages if we wanted. Doing this temporarily was good for mate choice experiments (since then we could ask females to choose between differentially-raised males who were presented in identical environments; Diez-Leon et al. 2013 PLoS One); good for boredom testing, as then all subjects could be tested in the same type of environment (Meagher & Mason 2010, PLoS One); and also great for any videoed tests that then could be scored blind to treatment. Dong so longer term, though very mean, was also useful because it revealed that enriched-deprived mink can became more inactive, as well as more stereotypic as you might expect, especially spending more time  “lying awake doing nothing” (Meagher et al. 2013 AABS).  

Most recently Maria used these cages to ask whether enrichment use would decline if ceiling height was made too low, and Andrea used them to try and replicate Becky’s boredom work and Jamie’s enrichment-use findings.

They’ve been a simply excellent resource, but last week Maria finally had to rip them down (to make way for her next experiment, and to allow Angelo to get rid of or thoroughly clean things that have been getting steadily grubbier and grubbier for years). She found this pretty emotional. It really is the end of an era.

House 10 now: