Preferences of minipigs for environmental enrichment objects.

The minipig is an increasingly popular species for use in behavioral and toxicologic studies. As a result, quantification of environmental enrichment preferences for this species is especially important. We exposed 6 individually housed prepubertal female Yucatan minipigs to 1 of 3 different objects on a rotating schedule: 2 sessions with a hard plastic ball (diameter, 21.0 cm), and 3 sessions each with a large plastic apple (diameter, 22.5 cm) and a soft rubber cone (height, 48.0 cm). Objects were changed every 4 to 5 d. The initial 15 min after each object change was recorded, and duration of object interaction and other behaviors (activity and interaction with the food bowl) were measured. Results indicated significantly longer interactions with the cone (mean +/- SE, 282 +/- 54 s) than the ball (14 +/- 3 s). Interactions with the apple (66 +/- 18 s) and ball did not differ significantly. Interactions with the apple decreased across the 3 sessions, whereas interaction with the cone remained high for most minipigs over the 3 sessions. Duration of activity appeared to be inversely correlated with duration of object interaction (that is, the longer the subject interacted with the object, the less it engaged in nonobject activity). These results provide valuable and practical information on the features of objects that minipigs appear to prefer and offer suggestions for future studies evaluating environmental enrichment paradigms with individually housed minipigs.