Hager, R., Lyst, S., Gigg, J. et al. 2010. The effects of environmental enrichment through larger cage type on behavioral patterns in rats. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 658 (Abstract #PS11).
Most behavioral research is conducted in lab-housed animals due to the significant advantages of a controlled environment. In an effort to enhance the welfare and to obtain more realistic measures of behavior, larger cages with an additional raised platform have been developed for rats, thus increasing spatial complexity. However, the effects of this change in environment on behavioral patterns, individual development, and maternal performance remain unexplored. Moreover, while the benefits of the new, large cage type to animal welfare seem obvious, there has been considerable debate about the impact of this change in environment on performance in experimental paradigms and comparability with data collected from animals kept in the old style cages. To date, no study has attempted to investigate and quantify possible changes in development and behavior. Using Lister hooded rats, we measure differences in key behavioral and developmental traits between individuals kept in the new style cages and those housed in old style cage. This project has the further aim to test hypotheses about predicted effects of cage type on specific parts of the brain and associated effects on task performance. General environmental enrichment and increased spatial complexity has been shown to impact hippocampus-dependent memory. For example, appetitive learning in the T-maze is dependent on the hippocampus and we predict, therefore, a beneficial effect of being raised in the larger (enriched) cages compared with the smaller (impoverished) cages. By contrast, the novel object recognition task is hippocampus-independent and we predict no effect of cage type on performance for this task. Our first results indicate effects of cage type on maternal provisioning and behavior as well as offspring short-term growth. We will further present the first preliminary data from task performance experiments between the 2 groups of rats and discuss the implications of our findings for animal welfare and development.