Female C57BL/6 mice show consistent individual differences in spontaneous interaction with environmental enrichment that are predicted by neophobia

Walker, Michael D.; Mason, Georgia

doi:10.1016/j.bbr.2011.06.003

Cited by 38 publications

(20 citation statements)

References 46 publications

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“…Second, why do individuals vary in their utilisation of enrichment? Like other species [101], mink show consistent individual differences in enrichment use [10]). Perhaps surprisingly, active, stereotypic animals appear to interact least with enrichment objects [10].…”

Section: Discussionmentioning

confidence: 92%

Benefits of a Ball and Chain: Simple Environmental Enrichments Improve Welfare and Reproductive Success in Farmed American Mink (Neovison vison)

et al. 2014

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Can simple enrichments enhance caged mink welfare? Pilot data from 756 sub-adults spanning three colour-types (strains) 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 hanging plastic chain or length of hose, while a second pair was left as a non-enriched (NE) control. At 8 months, more than half the subjects were killed for pelts, and 302 new females were recruited (half enriched: ‘late E’). Several signs of improved welfare or productivity 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 tended to copulate for longer. E females also weaned more offspring: about 10% more juveniles per E female, primarily caused by reduced rates of barrenness (‘late E’ females also giving 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. They should also stimulate future research into more effective practical enrichments.

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Section: Discussionmentioning

confidence: 92%

Benefits of a Ball and Chain: Simple Environmental Enrichments Improve Welfare and Reproductive Success in Farmed American Mink (Neovison vison)

et al. 2014

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“…e.g. [2]). These consumption values were regressed against the average values for both cage mates in the trials with the mesh compartments.…”

Section: Methodsmentioning

confidence: 99%

“…Three broad methods are common: temporary markings (e.g. tail marking with a marker pen [1] or shaving a patch of hair [2]), permanent mutilations (e.g. ear notching [3] or toe clipping [4]), or the addition of permanent identification tags (e.g.…”

Section: Introductionmentioning

confidence: 99%

Co-Housing Rodents with Different Coat Colours as a Simple, Non-Invasive Means of Individual Identification: Validating Mixed-Strain Housing for C57BL/6 and DBA/2 Mice

et al. 2013

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Standard practice typically requires the marking of laboratory mice so that they can be individually identified. However, many of the common methods compromise the welfare of the individuals being marked (as well as requiring time, effort, and/or resources on the part of researchers and technicians). Mixing strains of different colour within a cage would allow them to be readily visually identifiable, negating the need for more invasive marking techniques. Here we assess the impact that mixed strain housing has on the phenotypes of female C57BL/6 (black) and DBA/2 (brown) mice, and on the variability in the data obtained from them. Mice were housed in either mixed strain or single strain pairs for 19 weeks, and their phenotypes then assessed using 23 different behavioural, morphological, haematological and physiological measures widely used in research and/or important for assessing mouse welfare. No negative effects of mixed strain housing could be found on the phenotypes of either strain, including variables relevant to welfare. Differences and similarities between the two strains were almost all as expected from previously published studies, and none were affected by whether mice were housed in mixed- or single-strain pairs. Only one significant main effect of housing type was detected: mixed strain pairs had smaller red blood cell distribution widths, a measure suggesting better health (findings that now need replicating in case they were Type 1 errors resulting from our multiplicity of tests). Furthermore, mixed strain housing did not increase the variation in data obtained from the mice: the standard errors for all variables were essentially identical between the two housing conditions. Mixed strain housing also made animals very easy to distinguish while in the home cage. Female DBA/2 and C57BL/6 mice can thus be housed in mixed strain pairs for identification purposes, with no apparent negative effects on their welfare or the data they generate. This suggests that there is much value in exploring other combinations of strains.

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“…Coppens et al, 2010): E Manipulation was not closely related to recurrent perseveration; and, furthermore, these animals did alter their behaviour in a major way after being moved to Enriched housing, as we have seen, by greatly reducing their SBs and choosing to rest in previously inaccessible areas. Differential neophobia (fear of novelty) could be another cause: neophobia predicted infrequent enrichment use in mice housed similarly to our mink, with an extra enriched cage available at the end of a length of PVC tubing (Walker and Mason, 2011). However, as mentioned, highly stereotypic mink are not typically the most timid (Hansen and Jeppesen, 2006).…”

Section: Discussionmentioning

confidence: 86%

Individual differences in stereotypic behaviour predict individual differences in the nature and degree of enrichment use in caged American mink

Ahloy‐Dallaire

Meagher

Mason

2012

Applied Animal Behaviour Science

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a b s t r a c tEnvironmental enrichment (EE) reduces stereotypic behaviour (SB), but typically only partially. Using American mink (n = 17) as models, we tested the hypotheses that the effectiveness of EE reflects the degree to which subjects utilise it, and also the SB's degree of 'establishment' (its frequency and within-bout predictability). In Non-Enriched cages, our subjects performed Carnivora-typical Locomotor SBs; some also stereotypically scrabbled against the cage walls. Each mink was then enriched: re-housed in a cage connected by an overhead tunnel to a compartment enriched with manipulable objects and running water. Here, both types of SB declined (Locomotor SB: from 5.8% to 0.9% of observations; Scrabbling: from 1.6% to 0.2%). Individual differences in these lowered SB levels were stable, correlating positively between observation periods ( ≥ +0.66). Similar stability was evident in all measures of enrichment use (partial r ≥ + 0.74). However, predictions that EE would be least effective for 'established', i.e. highly frequent or predictable, SBs were not supported. Furthermore, nor did low enrichment use predict small reductions in SB: instead, unexpectedly, frequent interactions with enrichment items predicted the smallest absolute reductions in Locomotor SB (partial r = + 0.55). This was because the smallest reductions in this SB occurred in mink with the lowest pre-enrichment levels (partial r = −0.60), who also interacted most with the enrichments (partial r = −0.52). Mink with high pre-enrichment levels of Locomotor SB, in contrast, rarely interacted with the enrichments, instead becoming more inactive (partial r = + 0.52). These individuals were also perseverative (displaying more inappropriate response repetition in a previous food-rewarded guessing task), thence potentially behaviourally inflexible. However, their perseveration did not predict less interaction with enrichments. Furthermore, these animals did markedly alter their behaviour when enriched, reducing their SB and shifting their preferred resting locations from home cages to the overhead tunnels (partial r = + 0.70): individual differences that were, again, stable over time (co-variance across observation periods for inactivity in different areas: partial r ≥ +0.65). Individuals thus used enriched environments in consistent, qualitatively different ways that were predicted by pre-enrichment levels of Locomotor SB: low-SB mink became more active when enriched, frequently engaging with manipulable objects and running water, while high-SB subjects instead shifted resting locations and became more inactive. These divergent response styles are unexpected: not predicted by any current understanding of SB. The underlying mechanisms and generality to other species therefore now need investigation.

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Female C57BL/6 mice show consistent individual differences in spontaneous interaction with environmental enrichment that are predicted by neophobia

Cited by 38 publications

References 46 publications

Benefits of a Ball and Chain: Simple Environmental Enrichments Improve Welfare and Reproductive Success in Farmed American Mink (Neovison vison)

Benefits of a Ball and Chain: Simple Environmental Enrichments Improve Welfare and Reproductive Success in Farmed American Mink (Neovison vison)

Co-Housing Rodents with Different Coat Colours as a Simple, Non-Invasive Means of Individual Identification: Validating Mixed-Strain Housing for C57BL/6 and DBA/2 Mice

Individual differences in stereotypic behaviour predict individual differences in the nature and degree of enrichment use in caged American mink

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