Evaluation of the preference to and behavioral effects of an enriched environment on male rhesus monkeys.

Two environments were provided to laboratory rhesus monkeys to determine if the animals spent more time (for the purposes of this study, defined as the cage side preference) in an enriched cage side than an unenriched cage side. The side (right or left) of a double-wide cage in which the animal spent the most time (as determined by Chi square analysis) was initially determined during baseline observations. The "nonpreferred" side was then enriched during the experimental phase of the study. The enrichment consisted of a perch, a Tug-A-Toy suspended inside the cage, a Kong toy suspended on the outside of the cage, and a grooming board mounted on the outside of the cage. No statistically significant changes in use of the enrichments were detected over time. Fifty percent of the animals switched cage side preference to the enriched side during the study. All subjects showed reduced behavioral pathology during exposure to the enriched environment with a return of behavioral pathology when the enrichments were removed.