Papers by Jamie Ahloy Dallaire
Play is commonly used to assess affective states in both humans and non-human animals. Play appea... more Play is commonly used to assess affective states in both humans and non-human animals. Play appears to be most common when animals are well-fed and not under any direct threats to fitness. Could play and playfulness therefore indicate pre-existing positive emotions, and thence optimal animal welfare? We examine this question by surveying the internal and external conditions that promote or suppress play in a variety of species, starting with humans. We find that negative affective states and poor welfare usually do suppress play (although there are notable exceptions where the opposite occurs). Furthermore, research in children suggests that beyond the frequency or total duration of play, poor welfare may additionally be reflected in qualitative aspects of this heterogeneous behaviour (e.g. display of solitary over social play; and the ‘fragmentation’ of play bouts) that are often overlooked in animals. There are surprisingly few studies of play in subjects with pre-existing optimal welfare or in unambiguously highly positive affective states, making it currently impossible to determine whether play can distinguish optimal or good welfare from merely neutral welfare. This therefore represents an important and exciting area for future research.
Benefits of a Ball and Chain: Simple Environmental Enrichments Improve Welfare and Reproductive Success in Farmed American Mink (Neovison vison)
PLoS ONE, 2014
Can simple enrichments enhance caged mink welfare? Pilot data from 756 sub-adults spanning three ... more 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.
Applied Animal Behaviour Science, 2013
Effects of sub-optimal housing on inactivity vary across species and experiments, probably becaus... more Effects of sub-optimal housing on inactivity vary across species and experiments, probably because inactivity is heterogeneous, reflecting both positive states (e.g. relaxation) and negative ones (e.g. fear). We therefore aimed to identify specific subtypes of inactivity that could indicate poor welfare in mink, by comparing their behaviour in enriched and non-enriched conditions (the former having been previously demonstrated to be highly preferred by mink and to enhance their welfare). We assessed this in three groups of subjects, as well as after housing conditions were reversed for the last group. During live scans, inactive animals were scored for posture, location, and whether awake or apparently asleep. Data on temperament and physiological stress indicators were also collected for one group; these confirmed that non-enriched housing increased faecal cortisol metabolites (FCM; P=0.040). Non-enriched housing also increased locomotor stereotypy in females (sex*housing: P=0.004). Inactivity in the nest-box (vs. in the open cage) was higher among females in non-enriched housing (housing*sex P<0.001), and increased by 20% of observations after enrichment removal (P=0.018) for both sexes. Furthermore, males with fearful temperaments spent the most time inactive in the nest-box (sex*temperament P=0.054), while females whose FCM decreased most when given enrichment also showed the largest decreases in this behaviour (sex*FCM change P=0.019). Together, this suggests that inactivity in the nest-box may reflect anxiety-induced hiding. Lying awake (i.e. prone with eyes open) was also higher in non-enriched housing (3.1% of observations vs. 1.7%; P=0.002); furthermore, this subtype of inactivity increased after enrichment removal (by 1.0% of observations; P=0.021), and decreased when non-enriched mink were given enrichment (by 2.4% of observations; P=0.004). This behaviour did not co-vary with fearfulness, however, nor with FCM (both P>0.05). This suggests that lying awake is not fear-related (e.g. not reflecting enhanced vigilance) but instead reflects some other negative state. Effects on inactivity subtypes as defined by posture were less consistent. For example, time spent lying belly down tended to decrease in mink moved from non-enriched to enriched cages (P=0.054), but enriched mink spent significantly less time belly down (in one of the three groups; P=0.002). Overall, two subtypes of inactivity, lying in the nestbox and lying awake seem likely to be valid indicators of housing-induced poor welfare in this species, being consistently increased by non-enriched cages. Lying in the nest-box may indicate fear or anxiety, and lying awake, a boredom-like state.
Juvenile rough-and-tumble play predicts adult sexual behaviour in American mink
The existence of play, a form of behaviour without obvious benefits to survival or reproduction, ... more The existence of play, a form of behaviour without obvious benefits to survival or reproduction, is a long-standing ethological mystery. Experiments in which socially deprived juvenile male mammals develop into sexually incompetent adults, along with widespread sexual dimorphism in rough-and-tumble play (R&T), suggest that R&T may prepare juvenile males for adult sexual behaviour. To test this hypothesis, we conducted a longitudinal study of American mink, Neovison vison, on two farms, with two cohorts each. For males (N = 121), we predicted that individuals with the highest frequencies of rough-and-tumble play as juveniles (10–20 weeks old) would, as adults, show shorter latencies to bite females' necks and to begin copulating, and copulate for longer durations. On one farm, we conducted a pilot study of females (N = 10) as a preliminary test of the hypothesis that R&T also prepares females for adult sexual behaviour. Here, our predictions were the opposite of those for males, since abilities to limit the number or duration of copulations could allow females to exercise pre- or postcopulatory mate choice. In total, we observed 1669 male–female encounters and 1004 separate copulations. As predicted, frequent juvenile R&T predicted long-lasting copulations in adult males and longer latencies to copulate in adult females. This was true specifically of rough-and-tumble play itself, independently of general activity levels and, among a subset of 32 males reared in environmentally enriched housing, also independently of solitary object play. To our knowledge, this is the first demonstration that juvenile rough-and-tumble play predicts adult sexual behaviour in any species. Further research is required to test whether our results for females can be replicated, and, importantly, to determine whether play truly has a causal role in either of these correlational relationships.
Play in juvenile mink: litter effects, stability over time, and motivational heterogeneity
Mink are potentially ideal for investigating the functions of play: deleterious effects of early ... more Mink are potentially ideal for investigating the functions of play: deleterious effects of early social isolation suggest a crucial developmental role for play; and huge numbers of highly playful juvenile subjects can be studied on farms. We collected descriptive data on 186 pairs from 93 litters, half provided with play-eliciting environmental enrichment objects in their home cages, to test three hypotheses: (1) play frequency is subject to litter effects; (2) relative playfulness is stable over time; (3) play sub-types share a single, common motivational basis. We found weak litter effects that were driven by stronger litter effects on general activity, and weakly stable individual differences in both total and rough-and-tumble play. Experimentally increasing object play did not inhibit rough-and-tumble play, showing these sub-types are not motivational substitutes. Frequencies of these sub-types were also uncorrelated, and changed differently with time of day and age, further supporting this conclusion.
Background: Inefficient experimental designs are common in animal-based biomedical research, wast... more Background: Inefficient experimental designs are common in animal-based biomedical research, wasting resources and potentially leading to unreplicable results. Here we illustrate the intrinsic statistical power of split-plot designs, wherein three or more sub-units (e.g. individual subjects) differing in a variable of interest (e.g. genotype) share an experimental unit (e.g. a cage or litter) to which a treatment is applied (e.g. a drug, diet, or cage manipulation). We also empirically validate one example of such a design, mixing different mouse strains – C57BL/6, DBA/2, and BALB/c – within cages varying in degree of enrichment. As well as boosting statistical power, no other manipulations are needed for individual identification if co-housed strains are differentially pigmented, so also sparing mice from stressful marking procedures.
Methods: The validation involved housing 240 females from weaning to 5 months of age in single-or mixed-strain trios, in cages allocated to enriched or standard treatments. Mice were screened for a range of 26 commonly-measured behavioural, physiological and haematological variables.
Results: Living in mixed-strain trios did not compromise mouse welfare (assessed via corticosterone metabolite
output, stereotypic behaviour, signs of aggression, and other variables). It also did not alter the direction or
magnitude of any strain- or enrichment-typical difference across the 26 measured variables, or increase variance
in the data: indeed variance was significantly decreased by mixed- strain housing. Furthermore, using Monte
Carlo simulations to quantify the statistical power benefits of this approach over a conventional design
demonstrated that for our effect sizes, the split- plot design would require significantly fewer mice (under half in
most cases) to achieve a power of 80 %.
Conclusions: Mixed-strain housing allows several strains to be tested at once, and potentially refines traditional
marking practices for research mice. Furthermore, it dramatically illustrates the enhanced statistical power of
split-plot designs, allowing many fewer animals to be used. More powerful designs can also increase the chances of
replicable findings, and increase the ability of small-scale studies to yield significant results. Using mixed-strain housing
for female C57BL/6, DBA/2 and BALB/c mice is therefore an effective, efficient way to promote both refinement and
the reduction of animal-use in research.
PLoS ONE, Nov 2014
Can simple enrichments enhance caged mink welfare? Pilot data from 756 sub-adults spanning three ... more 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 colourtype
(‘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.
Plastic animals in cages: behavioural flexibility and responses to captivity
Animal Behaviour, 2013
Billions of wild and semiwild animals live in captive conditions very different from their ancest... more Billions of wild and semiwild animals live in captive conditions very different from their ancestral environments. Some of the potential challenges they face here, such as greater human proximity, constrained natural behaviours and altered climates, resemble those occurring during urbanization, translocation and other forms of human-induced rapid environmental change (HIREC) in the wild. These parallels between HIREC and captivity suggest that certain species could be in double jeopardy: struggling in both wild and captive environments. This raises new hypotheses for future research, including one tested in this paper: that a species' presence in captivity predicts its chances of establishment when translocated to novel natural habitats. Furthermore, understanding the mechanisms that predispose captive populations to thrive or fail can yield new insights into how animals respond to HIREC. For example, populations adjusting to captivity demonstrate rapid developmental effects. Within one generation, captive-reared animals may show beneficial phenotypic changes (e.g. smaller stress responses than F0s wild caught as adults), illustrating how adaptive developmental plasticity can help populations succeed. However, captive-reared animals also illustrate the risks of developing in evolutionarily new environments (being prone to reduced behavioural flexibility, and sometimes impaired reproduction), suggesting that disrupted ontogeny is one reason why HIREC can be harmful. Overall, analogies between captivity and HIREC are thus interesting and useful. However, captivity and HIREC do differ in some regards, captivity tending to be safer yet more monotonous; we therefore end by discussing how species-typical risk/protective factors, and the phenotypic changes induced in affected animals, may vary between the two.
Applied Animal Behaviour Science, 2013
Effects of sub-optimal housing on inactivity vary across species and experiments, probably becaus... more Effects of sub-optimal housing on inactivity vary across species and experiments, probably because inactivity is heterogeneous, reflecting both positive states (e.g. relaxation) and negative ones (e.g. fear). We therefore aimed to identify specific subtypes of inactivity that could indicate poor welfare in mink, by comparing their behaviour in enriched and non-enriched conditions (the former having been previously demonstrated to be highly preferred by mink and to enhance their welfare). We assessed this in three groups of subjects, as well as after housing conditions were reversed for the last group. During live scans, inactive animals were scored for posture, location, and whether awake or apparently asleep. Data on temperament and physiological stress indicators were also collected for one group; these confirmed that non-enriched housing increased faecal cortisol metabolites (FCM; P=0.040). Non-enriched housing also increased locomotor stereotypy in females (sex*housing: P=0.004). Inactivity in the nest-box (vs. in the open cage) was higher among females in non-enriched housing (housing*sex P<0.001), and increased by 20% of observations after enrichment removal (P=0.018) for both sexes. Furthermore, males with fearful temperaments spent the most time inactive in the nest-box (sex*temperament P=0.054), while females whose FCM decreased most when given enrichment also showed the largest decreases in this behaviour (sex*FCM change P=0.019). Together, this suggests that inactivity in the nest-box may reflect anxiety-induced hiding. Lying awake (i.e. prone with eyes open) was also higher in non-enriched housing (3.1% of observations vs. 1.7%; P=0.002); furthermore, this subtype of inactivity increased after enrichment removal (by 1.0% of observations; P=0.021), and decreased when non-enriched mink were given enrichment (by 2.4% of observations; P=0.004). This behaviour did not co-vary with fearfulness, however, nor with FCM (both P>0.05). This suggests that lying awake is not fear-related (e.g. not reflecting enhanced vigilance) but instead reflects some other negative state. Effects on inactivity subtypes as defined by posture were less consistent. For example, time spent lying belly down tended to decrease in mink moved from non-enriched to enriched cages (P=0.054), but enriched mink spent significantly less time belly down (in one of the three groups; P=0.002). Overall, two subtypes of inactivity, lying in the nestbox and lying awake seem likely to be valid indicators of housing-induced poor welfare in this species, being consistently increased by non-enriched cages. Lying in the nest-box may indicate fear or anxiety, and lying awake, a boredom-like state.
Behavioural Brain Research, 2013
Studies spanning 15 species (including American mink, Neovison vison) demonstrate that within sim... more Studies spanning 15 species (including American mink, Neovison vison) demonstrate that within similarly-housed populations, individuals displaying high levels of stereotypic behaviour (SB) typically show perseverative responding (e.g. during set-shifting, or reversal/extinction learning). Similar correlations in autism and schizophrenia suggest this indicates captivity-induced cortico-striatal circuit dysfunction. However, this pattern does not prove developmental impairment: SB, perseveration and their inter-correlations also occur in normal humans. We therefore differentially-reared enriched versus non-enriched mink to investigate whether treatments that exacerbate SB correspondingly increase perseveration (Study 1). Enriched-rearing did reduce SB and perseverative response repetition (in two-choice guessing tasks), while increasing spontaneous alternation: a strategy yielding more rewards, and suggesting enhanced hippocampal development. This complements previous research demonstrating cortical/hippocampal impairments and reduced behavioural flexibility in non-enriched animals, with implications for research animals and wild animals captive-raised for reintroduction into nature. Consistent with previous data, highly stereotypic subjects repeated guessing task responses most rapidly, suggesting disinhibition during repetition. However, unexpectedly, SB and perseveration did not co-vary across individuals. We therefore suggest that behavioural changes manifest as increased perseveration are important but do not fully explain captive animals’ SBs, possible reasons including the contributory role of differential motivations for underlying source behaviours. Re-analyses of old data (Study 2) confirmed that spontaneous alternation is profitable; and demonstrated that the precise methods used for quantifying perseveration and SB can modify the strength of apparent relationships between them, as can statistically controlling for feeding motivation: as predicted, partialling out motivational effects increased the variance in SB predicted by perseveration.
Applied Animal Behaviour Science, 2012
Environmental enrichment (EE) reduces stereotypic behaviour (SB), but typically only partially. U... more Environmental 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 (ρ≥+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.
Animal Welfare, 2012
Physical disability has the potential to impede the use of environmental enrichments in rehabilit... more Physical disability has the potential to impede the use of environmental enrichments in rehabilitation programmes. We therefore compared the behaviour of 63 disabled and non-disabled socially housed adult Asiatic black bears rescued from bile farms for 103 observation hours. Amputees were less active than non-amputees, spent less time standing, travelled less between different areas of their outdoor enclosure, and showed less frequent stereotypic behaviour. Blind bears also showed low levels of activity and stereotypic behaviour. Blind bears and male amputees spent less time than non-disabled bears eating food dispersed throughout the enclosure as a foraging enrichment. It is unclear whether their infrequent eating is due to impaired foraging, or to lower energy demands arising from lower activity levels. Blind bears tended to manipulate feeders and other enrichment objects less than sighted bears. Disabled bears did not show any signs of impaired social interactions, and were not competitively displaced from resources by other bears more often than non-disabled bears. Thus, disabled bears rescued from bile farms show deficits in overall activity, with amputees also travelling less around their enclosures and blind bears potentially compromised in some forms of enrichment use. However, it is apparent that they adapt well to the presence of social companions. Several disabled bears also showed a degree of novel behaviour, seemingly compensating for disabilities, suggesting possible avenues for enrichments targeted specifically at these bears. The data also suggest specific hypotheses to test in longitudinal studies of rehabilitation.
Behavioural Brain Research, 2011
We analysed the relationship between abnormal repetitive behaviour (ARB), the presence/absence of... more We analysed the relationship between abnormal repetitive behaviour (ARB), the presence/absence of environmental enrichment, and two types of behavioural disinhibition in farmed American mink, Neovison vison. The first type, recurrent perseveration, the inappropriate repetition of already completed responses, was assessed using three indices of excessive response repetition and patterning in a bias-corrected serial two-choice guessing task. The second type, disinhibition of prepotent responses to reward cues, a form of impulsivity, was tested in a locomotive detour task adapted from primate reaching tasks: subjects were required to walk around, rather than directly into, a transparent barrier behind which food was visible. In older adult females, recurrent perseveration positively predicted pre-feeding abnormal repetitive locomotion (ARL) in Non-enriched housing. High-ARL subjects also performed repeated (same-choice) responses more rapidly than low-ARL animals, even when statistically controlling for alternated (different-choice) response latency. Mink performed much less ARL following transfer to Enriched housing, but there was no corresponding change in recurrent perseveration. Thus, elevated recurrent perseveration is not sufficient for frequent ARL; and while captive environments do determine ARL frequency, in mink, they do not necessarily do so by modifying levels of perseveration. Disinhibition of prepotent responses to reward cues, meanwhile, did not predict ARL. In a separate sample of differentially housed young adults, neither type of behavioural disinhibition predicted ARL, and again, whether or not housing was enriched did not affect behavioural disinhibition despite affecting ARL. Thus, the relationship between recurrent perseveration and ARB may only develop with age; longitudinal studies are now required for confirmation.
Animal Behaviour, 2010
For captive animals, living in barren conditions leads to stereotypic behaviour that is hard to a... more For captive animals, living in barren conditions leads to stereotypic behaviour that is hard to alleviate using environmental enrichment. This resistance to enrichment is often explained via mechanisms that decouple abnormal behaviour from current welfare, such as ‘establishment’: a hypothetical process whereby repetition increases behaviour’s predictability and resistance to change. If such hypotheses are correct, then animals with enrichment-resistant stereotypic behaviour should still find enrichments rewarding. Alternatively, this behaviour could reflect a failure to improve welfare: plausible because age and chronic stress increase neophobia and anhedonia. If this hypothesis is correct, animals with enrichment-resistant stereotypic behaviour should value enrichments less than conspecifics. We tested these hypotheses using C57BL/6 mice, Mus musculus, aged 10–11 and 6–7 months, raised in barren laboratory cages. We observed their behaviour in both these and large enriched cages. Enrichment was more effective on the younger animals. However, contrary to ideas about establishment, the spontaneous predictability of stereotypic behaviour did not increase with age; nor was enrichment less effective on more predictable or time-consuming forms. We assessed the reward value of enriched cages by allowing access via progressively weighted doors (maximum weight pushed corresponding to peak motivation). In older mice, those individuals whose stereotypic behaviour was least reduced by enrichment were also the least motivated to gain access to enrichment. This suggests that the welfare of middle-aged-animals, as well as their stereotypic behaviour, is harder to improve using environmental enrichment.
Animal Welfare, 2009
Stress cues can affect the welfare of animals in close proximity and are possibly useful non-inva... more Stress cues can affect the welfare of animals in close proximity and are possibly useful non-invasive indicators of the emitters' welfare. To facilitate their study in murids, we tested whether rats' stress odours could be collected and stored using an enfleurage-type technique. 'Donor' rats were individually exposed to a compound stressor (carried circa 75 m inside a novel container, then euthanised with rising carbon dioxide) while on blotting paper dotted with melted vegetable lard. These sheets were sealed, left at room temperature for 2-5 h, and then 'bioassayed' by a blind observer for their effects on conspecifics. Compared with control sheets (exposed to unstressed rats, to CO₂ alone, or untreated), stress-exposed sheets significantly affected the unconditioned behaviour of 16 pairs of detector rats trained to enter an arena from their home cage to obtain sucrose. When used to line this arena, the stress-exposed sheets significantly increased: i) rats' latencies to eat, to place front feet into, and to completely step into the arena and ii) shuttling movements between arena and home cage. These pilot data thus suggest that odours produced by stressed rats can be simply and successfully collected and stored for several hours, though certain potential confounds (eg urine volume) may conceivably be alternative explanations for the observed effects. Future work should control for urine volume, and assess whether fat is needed for optimal odour absorption by paper and for how long sheets can be stored at various temperatures. Much fundamental work is also still needed on the nature, functions, and sources of stress odours.
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Papers by Jamie Ahloy Dallaire
Methods: The validation involved housing 240 females from weaning to 5 months of age in single-or mixed-strain trios, in cages allocated to enriched or standard treatments. Mice were screened for a range of 26 commonly-measured behavioural, physiological and haematological variables.
Results: Living in mixed-strain trios did not compromise mouse welfare (assessed via corticosterone metabolite
output, stereotypic behaviour, signs of aggression, and other variables). It also did not alter the direction or
magnitude of any strain- or enrichment-typical difference across the 26 measured variables, or increase variance
in the data: indeed variance was significantly decreased by mixed- strain housing. Furthermore, using Monte
Carlo simulations to quantify the statistical power benefits of this approach over a conventional design
demonstrated that for our effect sizes, the split- plot design would require significantly fewer mice (under half in
most cases) to achieve a power of 80 %.
Conclusions: Mixed-strain housing allows several strains to be tested at once, and potentially refines traditional
marking practices for research mice. Furthermore, it dramatically illustrates the enhanced statistical power of
split-plot designs, allowing many fewer animals to be used. More powerful designs can also increase the chances of
replicable findings, and increase the ability of small-scale studies to yield significant results. Using mixed-strain housing
for female C57BL/6, DBA/2 and BALB/c mice is therefore an effective, efficient way to promote both refinement and
the reduction of animal-use in research.
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 colourtype
(‘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.
Methods: The validation involved housing 240 females from weaning to 5 months of age in single-or mixed-strain trios, in cages allocated to enriched or standard treatments. Mice were screened for a range of 26 commonly-measured behavioural, physiological and haematological variables.
Results: Living in mixed-strain trios did not compromise mouse welfare (assessed via corticosterone metabolite
output, stereotypic behaviour, signs of aggression, and other variables). It also did not alter the direction or
magnitude of any strain- or enrichment-typical difference across the 26 measured variables, or increase variance
in the data: indeed variance was significantly decreased by mixed- strain housing. Furthermore, using Monte
Carlo simulations to quantify the statistical power benefits of this approach over a conventional design
demonstrated that for our effect sizes, the split- plot design would require significantly fewer mice (under half in
most cases) to achieve a power of 80 %.
Conclusions: Mixed-strain housing allows several strains to be tested at once, and potentially refines traditional
marking practices for research mice. Furthermore, it dramatically illustrates the enhanced statistical power of
split-plot designs, allowing many fewer animals to be used. More powerful designs can also increase the chances of
replicable findings, and increase the ability of small-scale studies to yield significant results. Using mixed-strain housing
for female C57BL/6, DBA/2 and BALB/c mice is therefore an effective, efficient way to promote both refinement and
the reduction of animal-use in research.
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 colourtype
(‘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.