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One of the favored options for generating complex transgenic laboratory mice is through in-house breeding and management strategies. One consideration in the management of these colonies is how the animals’ environment may affect reproductive success. Several aspects of the microenvironment can be controlled or manipulated, including cage type, bedding, enrichment, diet, and temperature and humidity. This study sought to evaluate reproductive outcomes for C57BL/6J mice that were randomly assigned to one of two different bedding types: paper based or corncob bedding. Our hypothesis was there would be no significant difference in reproductive outcomes between the two bedding types. A total of 10 males and 10 females were paired at 45 days of age. Animals were allowed to breed for 15 consecutive weeks. Cages were checked daily for the presence of pups and a pup count was performed at 7 days of age. Weaning occurred at 20 or 21 days of age, at which time a final pup count, pup weight, and sex were recorded. All litters born and pups weaned in the 15-week timeframe were used for data analysis. Statistical analysis compared cannibalization between the two groups and the results showed no statistical difference between groups (p > 0.05). Other parameters analyzed included average litter size, average weaning weight, and number of litters per group. All pups counted at Day 7 survived to weaning age in both groups. We concluded that both bedding types produced similar success regarding breeding fecundity in C57BL/6J mice. [ABSTRACT FROM AUTHOR]

Individual or singly-housing laboratory rats is common in many animal facilities, but has an adverse impact on the welfare of this social species. It has previously been shown that a small proportion of individually housed mice (∼5%) engage in pathological overgrooming behaviour, but this has not been assessed in rats. We performed an observational study to determine the prevalence of overgrooming-related self-injury and whether providing nesting material enrichment throughout an animal's life would affect the prevalence or severity of overgrooming-related self-injury. Due to protocol differences between projects in our behavioural neuroscience lab, unenriched rats received a nylabone and a shelter (n = 167), while baseline-enriched rats received a nylabone, shelter and shredded paper nesting material throughout experiments (n = 238). Unenriched rats received nesting material enrichment after the onset of overgrooming-related self-injury. Over 18 months, rats were monitored by their experimenters on a daily basis (5–7 days/week over 2–3 months/project) and any cases of overgrooming-related self-injury were recorded. Replicating the findings of previous studies in mice, we observed 20 cases of overgrooming-related self-injury (∼5%) with no difference in prevalence between rats on the basis of supplier, cage position, experimental procedure (behavioural only or involving surgical procedures), reinforcer (ethanol or sugar) or level of baseline-enrichment. While there was no difference in onset severity between rats that were unenriched at baseline and baseline-enriched rats, baseline-enriched rats had lower self-injury severity scores at one-, two- and four-week follow-ups. These results suggest that nesting material enrichment provided throughout an animal's life may reduce overgrooming-related self-injury. [ABSTRACT FROM AUTHOR]

Preference tests were used to assess a range of enrichment options for rats kept under standard New Zealand (and similar) caging conditions. The rats did not show significant preferences for most of the options, over an empty cage. The exceptions were shredded paper, a nesting box and a semi-enriched condition incorporating a range of modifications. These cage modifications are recommended for the enrichment of laboratory rats. [ABSTRACT FROM AUTHOR]

A proper cage environment is essential for the welfare of laboratory mice, especially for females during the energy demanding lactation period and for pups during early development and growth. The most common housing system for laboratory mice is individually ventilated cages (IVCs) of which there are different layouts and ventilation strategies available on the market. The present study investigates the impact of cage environment in three different IVC types, on the maternal performance of females, and pup development and growth in C57BL/6NCrl and Crl:NMRI Foxn1nu mice. The results show differences in in-cage climate, female body weight, pup growth, feed and water consumption, and nest quality between cage types. There was a distinct effect of genotype in these differences, with the main effects found in NMRI NU mice. The results indicate that IVC systems might need to be managed differently for mice of different types and/or different physiological status. Many of the differences seen between cage systems could be drawn to the physical construction of the cage, such as location of feed hopper and location of air inlet and outlet. In conclusion, IVC in-cage climate affects the maternal performance of female mice and pup growth, but with differences between the two strains tested. [ABSTRACT FROM AUTHOR]

The ideal animal model would contribute no confounding variables in experimental science. Variables affect experimental design resulting in increased animal use or repeated studies. We demonstrated a simple refinement which may reduce the number of animals used experimentally while simultaneously improving animal welfare. The objective of this study was to determine if the presence of a hut was an impact on physiological stress levels, as determined by faecal cortisol concentration, during a routine four-day acclimatization period of newly received male Hartley-Outbred guineapigs. We hypothesized that those animals provided with huts would have decreased physiological stress compared with animals not provided with huts. We examined this effect within both paired and single-housed animals. A between-subjects one-way analysis of variance revealed that pair-housed animals with a hut had significantly lower faecal cortisol concentration than pair-housed animals without a hut and the presence and absence of a hut had no significant impact on faecal cortisol concentration in single-housed animals. These findings show that presence of a hut is beneficial in reducing physiological stress when pair housing male guineapigs and does not appear to have an impact when single housing male guineapigs. In addition, we have shown that faecal cortisol, and therefore physiological stress, is still increasing on study day 4 suggesting a longer acclimatization period is necessary. A simple refinement in housing environment and acclimatization time can both reduce the number of animals used experimentally and improve animal welfare. [ABSTRACT FROM AUTHOR]

In the animal facility, a range of different sounds are present. On the one hand, rats and humans will regard sound and noise differently even within the audible range, but on the other hand mice and rats being very adaptable to the environment may adapt to living in a noisy facility with e.g. a radio playing. It was the aim of the present study to investigate whether two different strains of rats had different preferences for different kinds of sound patterns, including radio, and to get an indication of whether they are able to distinguish between different sound patterns. The present preference study revealed that rats were able to distinguish between different sound patterns. They showed a clear preference for silence to anything else, which may be taken as an indication that they feel disturbed by the sound from the speaker. [ABSTRACT FROM AUTHOR]

Standard housing for laboratory mice severely restricts natural behaviour and the control that the animal has over its environment. Providing the cage with objects is a method that has been used to both increase environmental complexity, promote the performance of natural behaviour and provide greater controllability for the animal. This method of furnishing cages has mostly been studied in adult animals, and little is known about the influence that the preweaning environment has on the behaviour of mice as adults. This study aimed to investigate the effects on mice behaviour of preweaning and postweaning housing environment. In this experiment, 64 pairs of animals of the strain C57BL/6J were used. Half of the animals were born and reared until weaning in standard cages and the other half in cages twice the size of the standard and furnished with nesting material, a cardboard tube, a PVC nest box and a wooden chewblock. After weaning, half the animals in each group were changed to the other type of cage, whereas the other half remained in the same environment; in both cases they were kept in single-sex pairs of littermates. Behaviour during the dark, active period was studied through video recordings. We found no main effects of preweaning environment on behaviour; however, mice moved from furnished to standard cages at weaning showed a decrease in inactive behaviour at four weeks of age. Mice housed after weaning in standard cages spent less time inactive, and more time engaging in activities like feeding and drinking, self-grooming and allogrooming. A sex difference was also found, in that females showed a greater performance of exploratory behaviour as well as a greater prevalence of stereotypies. The use of different objects and locations within the furnished cage was also analysed at both ages. Results show that at eight weeks of age mice spent more time at the top of the cage, and that the use of the nest box (although not for resting) increased between four and eight weeks. Mice were found to use the nest box as a nesting site/sleeping place only at age four weeks, whereas they always used the nesting material for sleeping. [ABSTRACT FROM AUTHOR]