Laboratory mice persist in gaining access to resources: a method of assessing the importance of environmental features (1996)

Sherwin, C. M.

Abstract

By using traverses of shallow water in two experiments, it was determined how laboratory mice defended gaining access to feed, shelter, a conspecific or increased space (Experiment 1), and to feed, a running wheel, enrichments ('toys') or deep sawdust (Experiment 2). In both experiment, the mice continued to gain access to each of the resources several times each day despite having to traverse water, indicating that none of the resources was perceived as a luxury. .... Unexpectedly, there were no significant differences in the slopes of the regression lines for the resources examined here. Therefore, defending the frequency of visits to each of the non-food resource was perceived by the mice to be as important as defending frequency of visits to food. ....It was entirely possible for the mice to have survived indefinitely by remaining in the 'feed' cage (this was constructed to simulate a standard laboratory cage). However, the mice repeatedly visited each of the other resource cages even when the cost of gaining access was increased [increased length of water traverse]. ... These results indicate that a wide variety of resources were perceived by laboratory mice as important, and suggest that conventional designs of cage which provide only food, water, companionship and a thin layer of sawdust might be inadequate with regards to welfare ... and could lead to suffering.