Influence of food enrichment on cage side preference.

A preference test paradigm was used to assess the value of two enrichment techniques for rhesus macaques (Macaca mulatta): 1) a Kong toy stuffed with food treats and 2) a fleece board covered with particulate food. The duration of time spent in the enriched cage side was compared with that spent in the unenriched cage side. Additionally, the number of cage side changes made during an observation interval and the duration and frequency of occurrence of select behaviors were recorded. Half the subjects altered their cage side preference during the experimental condition, and a fifth animal reversed side preference in the postexperimental phase. Subjects spent a mean time of 14% of a session engaged with the foraging devices. The occurrence of several behaviors, including self-directed and locomotor activities, varied significantly with the experimental condition. These results were compared with data from a previous preference study of nonnutritive enrichments, and a hypothesis regarding the relative value of different types of enrichment was developed.

Kong toys for laboratory primates: are they really an enrichment or just fomites?

Simple toys as enrichment devices have been associated with a rapid decline in their use by nonhuman primates. Other facets of toy presentation have not been described previously. For example, a comparison of the effect(s) of an enrichment device between two facilities should be validated if enrichment recommendations are to be made that affect diverse research facilities across the country. Additionally, a comparison of two methods of presentation (one highly accessible to the animal and the other less accessible) of the same enrichment device for potential differences in efficacy could provide direction in implementing an enrichment program based on simple toys. The handling of enrichment devices by nonhuman primates can lead to the spread of microbial contamination. The typical enrichment program rotates enrichment devices among animals to maximize the variety of stimuli available to each primate in the most economic manner. An adequate sanitation program is therefore pivotal to minimizing the potential for enrichment devices to be fomites. We conducted three experiments that addressed these issues. The results confirmed that, although the presence of a simple toy reduced behavioral pathology, there was variability in behavioral effect for an enrichment technique between facilities. Two methods of presentation (on floor and suspended) of a simple toy did not produce any significant differences in use. Finally, we demonstrated that microbial growth can persist on enrichment devices after they have been sanitized in a commercial cagewasher.