Cage Enrichment Research Articles

Cage enrichment and mouse behaviour

Mice housed in standard cages show impaired brain development, abnormal repetitive behaviours (stereotypies) and an anxious behavioural profile, all of which can be lessened by making the cage environment more stimulating. But concerns have been raised that enriched housing might disrupt standardization and so affect the precision and reproducibility of behavioural-test results (for example, see ref. 4). Here we show that environmental enrichment increases neither individual variability in behavioural tests nor the risk of obtaining conflicting data in replicate studies. Our findings indicate that the housing conditions of laboratory mice can be markedly improved without affecting the standardization of results.

Effect of enrichment on variation and results in the light/dark test.

Several confounding factors may influence the outcome of an experiment and the extent of inter-individual variation. The aim of this study was to investigate if cage enrichment induces an effect on experimental mean values and on inter-individual variation in the light/dark paradigm using diazepam as the anxiolytic drug. The behaviour of 216 naive adult male mice of two different strains (BALB/c and C57BL/6) was studied. The animals were housed in groups of four in 'non-enriched', 'enriched' (nesting material) or 'super-enriched' (nest-box, nesting material, wooden gnawing stick and PVC tube) cages. After 5 weeks the animals were assigned to one of three treatments: control (no injection), sham (saline injection i.p.) or diazepam (1 mg/kg bw i.p.) and tested in the light/dark test for 5 min. Variation data were analysed using three different methods (mean absolute deviation, coefficient of variation and power analysis). The C57BL/6 mice scored higher than BALB/c mice in activity related measurements and showed a less 'emotional' behaviour profile in the pharmacological control situation of the light/dark test. In this study the anxiolytic effect of diazepam was clear in BALB/c mice but absent in C57BL/6 mice. Mice housed in enriched and super-enriched cages gained more weight than mice in non-enriched cages, although food intake was not affected. Generally, the strain of mouse had the greatest impact on both mean values and variation. However, there was no consistent increase for one particular strain. The choice of statistical method for analysing variation may influence the interpretation of within-group variability, but none of the methods showed any significant differences between standard and enriched conditions on variability in any of the parameters measured.

Effect of Cage Enrichment on the Daily Use of Running Wheels by Syrian Hamsters

Institutional animal care committees may one day require for the welfare of captive hamsters more floor space and the introduction of tunnels and toys. As hamsters are popular animal subjects in chronobiological research, and as clock phase is usually measured through running wheel activity, it is important to determine what effect cage enrichment might have on daily wheel use. Here the daily number of wheel revolutions, the daily duration of the running activity phase, the phase relationship between lights-off and onset of running activity, and the free-running period of circadian activity rhythms were measured in Syrian hamsters, Mesocricetus auratus, housed in single cages or in multiple cages linked by tunnels and supplied with commercial wooden toys. Free-running periodicity was not affected by cage enrichment. In multiple-cage systems, there were fewer daily revolutions, shorter wheel-running activity phases, and delayed running activity onsets. These effects, however, were small as compared to interindividual and week-to-week variation. They were statistically significant only under a light:dark cycle, not in constant darkness, and only when interindividual variation was eliminated through a paired design or when the number of cages was increased to five (the maximum tested). Daily wheel use is thus affected by cage enrichment, but only slightly.

Effects of Environmental Enrichment for Mice: Variation in Experimental Results

This study focused on the effects of different enriched environments for mice in a number of behavioral and physiological parameters in 2 routine laboratory testing procedures: potency testing for tetanus vaccine and stress-induced hyperthermia. The variability in the results was studied by calculating and analyzing mean absolute deviations. Mice from enriched conditions weighed more and consumed more food than mice from standard housing conditions. However, mice from enriched conditions lost more body weight after being housed individually. Other physiological parameters showed no differences. Mice from standard conditions were more active in an open field, suggesting a tendency to overrespond to various stimuli in a testing environment. Mice from enriched environments were more tranquil and easier to handle. The enrichment did not influence the variability in any of the parameters measured, although earlier results and results of other studies suggest that the effects on the variability in results are parameter dependent. When enrichment does not influence variability, there is no reason for not introducing cage enrichment and by doing so contributing to the animals' welfare.

Influence of cage enrichment on aggressive behaviour and physiological parameters in male mice

From welfare perspective group housing of mice is preferred over individual housing. Group housing of male laboratory mice, however, often leads to problems due to excessive aggressive behaviour. In our search for management and housing modifications to decrease aggression in group-housed male laboratory mice, we have tested the effect of two types of environmental enrichment—nesting material and shelter—on aggressive behaviour after cage cleaning and after a 1 h isolation period. Severity of wounds, urinary corticosterone levels, body weight, food and water intake and several post-mortem parameters were also monitored. The results indicated that type of enrichment strongly affected both aggressive behaviour and physiological parameters. Overall, nesting material reduced aggressive behaviour, while a shelter increased aggressive behaviour compared to control housing. This effect was also reflected in the number of wounds counted. Furthermore, during shelter housing mice gained less body weight, drank less and showed higher corticosterone levels, while in housing conditions with nesting material, mice ate less. We conclude that providing male mice with nesting material reduces aggression between male mice, and may, thus, be promoted as being beneficial to their physical health and psychological well-being.

Repetitive Backflipping Behaviour in Captive Roof Rats(Rattus Rattus)and the Effects of Cage Enrichment

AbstractRepetitive ‘stereotyped’ behaviours are often performed by both wild and domestic rodents in small laboratory cages. In this study, a behaviour resembling a backwards somersault or backflip is described and quantified in captive roof rats (ship or black rats,Rattus rattus). Videotapes of captive-bred rat pups showed that repetitive backflipping developed rapidly after weaning. In all subjects, the behaviour was highly cyclical, with more than 90 per cent occurring during the dark phase of the light:dark cycle. Individual variability in the performance of backflipping was considerable but performance levels for each individual were consistent from day to day and at 30 and 60 days of age. Highly significant differences were found between litters (families), indicating important maternal and/or genetic effects on performance levels. Cage enrichment in the form of a wooden nest box resulted in dramatically lower rates of performance. Increased cage height resulted in delayed development of backflipping, as well as changes in the form of the behaviour. Results are consistent with the hypothesis that the development and expression of backflipping in young roof rats may be triggered by weaning and maintained by a heightened state of arousal in a relatively impoverished environment with limited opportunities for perceptual and locomotor stimulation.

The Development of a Novel Form of Mouse Cage Enrichment

This article describes the design and testing of a novel form of mouse cage enrichment. A cage insert was designed and developed to fulfill a number of enrichment goals pertaining to its effectiveness and practicality (i.e., to improve the environment of mice in laboratories while causing the minimum of interference to the husbandry and care procedures carried out by animal care staff). Behavioral and physical parameters were used over an 8-week period to assess effectiveness, with subjective opinions of cage cleaning staff and physical examinations of the inserts after cleaning being used to assess practicality. Results show that the insert was both a practical and effective form of mouse enrichment which produced a number of enriching effects without adversely affecting the animals, their environment, or the husbandry and care procedures.

The Use of Cage Enrichment to Reduce Male Mouse Aggression

The complete cleaning of cages has been shown to reduce the level of intermale aggression in mice. This study investigated the effects of the addition of enrichment objects on postcage-cleaning aggression in male BALB/c mice. Enrichment objects were found to significantly reduce aggressive interactions during this period for up to 7 weeks and can make an overall economic saving to husbandry costs.

The effect of cage size and enrichment on core temperature and febrile response of the golden hamster

The aim of this study is to determine the effect of cage size and cage enrichment. Golden hamsters were individually housed in standard cages of four different sizes and in enriched cages of three different sizes since 3 weeks of age. Each of the seven housing groups consisted of 12 hamsters. After 14 weeks of housing in their respective environments the measurements started. The mean baseline rectal temperature was significantly higher in hamsters housed in small cages than in hamsters housed in large cages. After the injection of fever-inducing lipopolysaccharide rectal temperature increased by 1 to 2 degrees C. The increase of rectal temperature and the fever index were the highest in animals housed in large cages and the smallest in animals housed in small cages. Through cage enrichment and increasing cage size the mean febrile response increased while the mean baseline rectal temperature decreased. Cage size and cage enrichment had no effect on the dispersion of the measured values. The differences in microclimate between large and small cages were too small to have an effect on thermoregulation. The results indicate that housing in small cages induce chronic stress which obviously affects thermoregulation. The findings demonstrate that the results of some physiological experiments are significantly influenced by the pre-experimental housing conditions.

Basic Husbandry and Clinical Assessment of the Amphibian Patient

The veterinarian presented with an amphibian patient must be prepared to assess both the animal's medical condition and its husbandry record; good health is inextricably linked to proper care and diet. This article provides the clinician with guidelines for maintaining amphibians in captivity, including information on climate control and lighting, housing and cage enrichment, and nutrition. The article also covers questions to ask when taking a history, methods of restraint, and practical advice on the equipment and techniques used to conduct a complete physical examination of the amphibian patient.

Effects of Experience and Cage Enrichment on Predatory Skills of Black-Footed Ferrets (Mustela nigripes)

We studied ontogeny of predatory skills of growing black-footed ferrets ( Mustela nigripes ) raised under different captive conditions. To test effects of maturation, experience, and cage enrichment on predatory behavior, we exposed 70 juvenile black-footed ferrets to different numbers of live hamsters ( Mesocricetus auratus ) throughout development. Both maturation and experience increased the likelihood of a black-footed ferret making a successful kill. Black-footed ferrets exposed to greater environmental complexity (enriched cage, including encouragement of food-searching behaviors) also were more likely to kill than ferrets raised in a deprived environment. Behavioral studies of captive-raised black-footed ferrets can help refine current breeding techniques and ultimately enhance efforts to recover this endangered carnivore.

Strength of preference for nesting material as environmental enrichment for laboratory mice

The present paper describes two experiments in which preferences of laboratory mice for materials which could serve as cage enrichment were investigated. In the first experiment, presence of nesting material (paper towel or tissue) and the presence of a nest box (perforated metal or clear perspex box) were tested against each other. On average, the 47 mice tested spent significantly more time in the cage with the nesting material (more than 69% of their total time, whereas less than 25% of their time in the cage with the nest box). In the second experiment, the preferred nesting material (tissues) was placed in a cage with a grid floor (previously found to be avoided) and the next box (perforated metal) was placed in another cage, connected to the first, with a solid floor covered with sawdust bedding material. In this experiment, 24 female mice were tested and on average they spent more than 67% of their time in the cage with the nesting material, despite the presence of a grid floor. Thus, it is concluded that providing a cage with nesting material (in addition to bedding) may be essential for the well-being of laboratory mice.

Behavioural Effects of Cage Enrichment in Single-Caged Adult Cats

AbstractThe behaviour of 10 adult individually-caged male cats was measured either in their normal cage or with additional objects, a log and a ball. Each cat was observed during five days in each condition. Results show an important novelty effect at the beginning of observations, especially for rubbing and paddling behaviour. Introduction of objects in the cages resulted in a decrease in inactivity and self-play activities, and an increase in sniffing objects and play behaviours with objects. This was particularly important with the ball. Whereas these modifications decreased over days with the log, a high level of activity was maintained with the ball. The importance of the movement and of the function of the object is discussed. An improved way of rearing isolated cats is suggested.

Zebra Finch Behaviour and Effect of Modest Enrichment of Standard Cages

AbstractZebra finches are often housed in monogamous pairs in small barren cages. In the present study it was investigated whether modest enrichment resulted in behavioural changes. Four plywood box cages of two different lengths were compared. A small and a large cage were used for the barren environment. Another small and large cage were used for the enriched environment, and included additional perches, twigs as well as sand and water baths. An ethogram consisting of 19 different behavioural patterns was used. The behaviour of the birds was studied using a combination of alternating (20s) one-zero and instantaneous sampling, one hour per day during a continuous four-week period.Locomotor activity, vocalization and singing was significantly increased in the enriched cages and flying was more frequent in the large enriched cage than in any of the other cages. The study demonstrated the usefulness of behavioural analyses to determine to what extent simple enrichment allows the birds to exhibit a wider range of their natural behaviour.