Rebecca K. Meagher

Environmental Enrichment Reduces Signs of Boredom in Caged Mink

Animals housed in impoverished cages are often labelled ‘bored’. They have also been called ‘apathetic’ or ‘depressed’, particularly when profoundly inactive. However, these terms are rarely operationally defined and validated. As a negative state caused by under-stimulation, boredom should increase interest in stimuli of all kinds. Apathy (lack of interest), by contrast, should manifest as decreased interest in all stimuli, while anhedonia (loss of pleasure, a depressive symptom) should specifically decrease interest in normally rewarding stimuli. We tested the hypotheses that mink, a model carnivore, experience more boredom, depression-like apathy, or anhedonia in non-enriched (NE) cages than in complex, enriched (E) cages. We exposed 29 subjects (13 E, 16 NE) to ten stimuli categorized a priori as aversive (e.g. air puffs), rewarding (e.g. evoking chasing) or ambiguous/neutral (e.g. candles). Interest in stimuli was assessed via latencies to contact, contact durations, and durations oriented to stimuli. NE mink contacted all stimuli faster (P = 0.003) than E mink, and spent longer oriented to/in contact with them, albeit only significantly so for ambiguous ones (treatment*type P<0.013). With stimulus category removed from statistical models, interest in all stimuli was consistently higher among NE mink (P<0.0001 for all measures). NE mink also consumed more food rewards (P = 0.037). Finally, we investigated whether lying down while awake and stereotypic behaviour (both increased by NE housing) predicted these responses. Lying awake positively co-varied with certain measures of increased exploration. In contrast, stereotypic ‘scrabbling’ or locomotion (e.g. pacing) did not. Overall, NE mink showed no evidence of apathy or depression, but instead a heightened investigation of diverse stimuli consistent with boredom. This state was potentially indicated by spending much time lying still but awake (although this result requires replication). Boredom can thus be operationalized and assessed empirically in non-human animals. It can also be reduced by environmental enrichment.

Recurrent perseveration correlates with abnormal repetitive locomotion in adult mink but is not reduced by environmental enrichment

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.

Social housing improves dairy calves' performance in two cognitive tests.

Early social housing is known to benefit cognitive development in laboratory animals. Pre-weaned dairy calves are typically separated from their dam immediately after birth and housed alone, but no work to date has addressed the effect of individual housing on cognitive performance of these animals. The aim of this study was to determine the effects of individual versus social housing on two measures of cognitive performance: reversal learning and novel object recognition. Holstein calves were either housed individually in a standard calf pen (n = 8) or kept in pairs using a double pen (n = 10). Calves were tested twice daily in a Y-maze starting at 3 weeks of age. Calves were initially trained to discriminate two colours (black and white) until they reached a learning criterion of 80% correct over three consecutive sessions. Training stimuli were then reversed (i.e. the previously rewarded colour was now unrewarded, and vice-versa). Calves from the two treatments showed similar rates of learning in the initial discrimination task, but the individually housed calves showed poorer performance in the reversal task. At 7 weeks of age, calves were tested for their response to a novel object in eight tests over a two-day period. Pair-housed calves showed declining exploration with repeated testing but individually reared calves did not. The results of these experiments provide the first direct evidence that individual housing impairs cognitive performance in dairy calves.

Early pair housing increases solid feed intake and weight gains in dairy calves.

Dairy calves have traditionally been kept in individual pens throughout the milk-feeding period. Social rearing is associated with increased solid feed intake and, hence, higher weight gains before and after weaning. Little is known about the effect of the age at which social housing begins. The aim of this study was to assess the effects of early versus late pairing on feeding behavior and weight gain before and after weaning. Holstein bull calves were reared individually (n=8 calves) or paired with another calf at 6±3 d (n=8 pairs) or 43±3 d of age (n=8 pairs). All calves were fed 8 L of milk/d for 4 wk, 6 L/d from 4 to 7 wk, and then milk was reduced by 20%/d until calves were completely weaned at 8 wk of age. Calves were provided ad libitumaccess to calf starter and a total mixed ration (TMR). Body weight and feed intake were measured weekly from 3 to 10 wk of age.Intake of calf starter was significantly higher for the early-paired calves than for individually reared and late-paired calves throughout the experimental period. At 10 wk of age, starter dry matter intake averaged 2.20±0.22, 1.09±0.25, and 1.26±0.33kg/d for early-paired, late-paired, and individually housed calves, respectively. Intake of TMR did not differ among treatments, TMR dry matter intake averaged 3.27±0.72, 3.08±0.46, and 2.89±0.54kg/d for the same 3 treatments. Calves in the early paired treatment also showed significantly higher average daily gain over the experimental period (0.89±0.04 vs. 0.76±0.04 and 0.73±0.04kg/d for the early-paired, individual, and late-paired calves, respectively). These results indicate that social housing soon after birth can increase weight gains and intake of solid feed.

Effects of Degree and Timing of Social Housing on Reversal Learning and Response to Novel Objects in Dairy Calves.

Rodents and primates deprived of early social contact exhibit deficits in learning and behavioural flexibility. They often also exhibit apparent signs of elevated anxiety, although the relationship between these effects has not been studied. To investigate whether dairy calves are similarly affected, we first compared calves housed in standard individual pens (n = 7) to those housed in a dynamic group with access to their mothers (n = 8). All calves learned to approach the correct stimulus in a visual discrimination task. Only one individually housed calf was able to re-learn the task when the stimuli were reversed, compared to all but one calf from the group. A second experiment investigated whether this effect might be explained by anxiety in individually housed animals interfering with their learning, and tested varying degrees of social contact in addition to the complex group: pair housing beginning early (approximately 6 days old) and late (6 weeks old). Again, fewer individually reared calves learned the reversal task (2 of 10 or 20%) compared to early paired and grouped calves (16 of 21 or 76% of calves). Late paired calves had intermediate success. Individually housed calves were slower to touch novel objects, but the magnitude of the fear response did not correlate with reversal performance. We conclude that individually housed calves have learning deficits, but these deficits were not likely associated with increased anxiety.

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

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.

Feather-damaging behaviour in companion parrots: an initial analysis of potential demographic risk factors

Captive parrots (Psittaciformes) commonly engage in “feather-damaging behaviour” (FDB) that suggests compromised welfare. Susceptibilities to FDB have been suggested, but not empirically demonstrated, to vary across the > 200 species kept in captivity. Other demographic risk factors have been proposed for particular species – but neither confirmed nor generalised across Psittaciformes. In this preliminary study, we analysed data from a previously-conducted survey of pet owners: among 538 companion parrots representing 10 non-domesticated, non-hybrid species (n ≥ 17/species), FDB prevalence was 15.8% overall. We tested whether individual FDB status was predicted by four previously-suggested demographic risk factors: species, sex, age, or hatch origin. Available (limited) data on husbandry were assessed as potential confounding variables and controlled for as appropriate. Species identity was a predictor of FDB status (P = 0.047), even after controlling for all other variables tested; however, in light of multiple statistical testing, this effect cannot be considered robust until it is replicated. The strongest predictors of FDB status were age (P = 0.001; with odds of positive FDB status lower in juveniles versus adolescents or adults [P ≤ 0.036]), and sex (P = 0.006; with odds of FDB lower in individuals of unknown, versus known, sex [P ≤ 0.037]). These findings need to be replicated with data that allow better statistical controls for systematic differences in housing. However, they do provide preliminary empirical evidence for within-species risk factors (suggesting new, testable hypotheses about the etiology of parrot FDB); and for intrinsic, cross-species differences in FDB susceptibility (providing a rationale for future study of the biological factors that might underpin any such taxonomic differences).

Simple year-round cage enrichments for mink

Subjects were 2,400 kits from 600 families, on 3 commercial farms in Ontario, pair-housed from July-December. 75% were Blacks, 25% Demis. Two male-female pairs were used per family: one was provided with stimuli for interaction; the other housed in standard conditions. The supplemented cages received a golf ball, plastic wiffle ball, and hanging device to tug /chew (hose or plastic chain) (costing under

Observer ratings: validity and value as a tool for animal welfare research

1.50 a cage). Behaviour, temperament, mortality rates and pelt quality were assessed. Supplemented kits were found to play more than their non-enriched siblings. Social play (defined as ‘rough and tumble’ interactions without screaming or hard biting) was unaffected, but enhanced object and locomotor play led to significantly higher overall levels in supplemented juveniles. There was no evidence that the added objects increased aggression. The added objects also had no effects on mortality. In stick tests in December, supplemented mink were significantly less likely to be fearful than their standard-housed siblings. When scored for reactions to the live-grading of their fur in November, supplemented mink were significantly less likely to scream than their standard-housed siblings. Across Blacks, the added objects did not seem to affect fur quality, but in Demis, supplemented mink were significantly likely to receive better live-grades than their standard-housed siblings. For pelted subjects, tails of dead animals were inspected for signs of tail-chewing/clipping. Typically 1 cm or less of the tailtip was affected. However, 20 mink across all three farms showed damage to 2 cm or more the tail, and 14 of these were standard-housed rather than supplemented: a trend to significance. Furthermore, pooling all instances of tail-chewing/-biting together, 7.9% supplemented mink had sucked/bitten tails, compared to 11.5 standard-housed: a significant effect. The pelts of all experimental mink were bar-coded for auction, and prices will be obtained in summer 2012. Data during mating showed that supplemented males were more effective maters than standard mink (e.g. showing longer copulations). Subjects selected for breeding have also been evaluated for stereotypic behaviour and faecal cortisol metabolite output, and for whelping success: data still to be analysed. Overall, these findings to date show that simple, long-term, cheap additions to standard cages can act as effective environmental enrichments for farmed mink.