Rhesus monkeys newly introduced to laboratory environments often show signs of stress, including reduced appetite and stereotypic behaviors. Foraging is a natural behavior that supports primate well-being, and puzzle feeders are thought to encourage such activity. This short-term study investigated whether the use of a puzzle feeder would affect food intake and reduce abnormal behavior in newly acquired rhesus monkeys housed individually.
– Subjects: 5 female rhesus monkeys (47–58 months old), newly imported and housed individually.
– Design: Each monkey experienced two feeding conditions—standard bucket feeding and puzzle feeder—over a 16-week period.
– Puzzle Feeder: A maze-like Plexiglas box requiring manipulation to retrieve food.
– Measurements:
– Food intake (as percentage of pellets consumed),
– Feeding time (time spent retrieving pellets),
– Body weight, and
– Stereotypic behavior (e.g., pacing, floor rubbing).
– Food intake: No significant difference between the two conditions (88.6% with bucket vs. 87.4% with puzzle feeder).
– Feeding time: Significantly longer with the puzzle feeder (812.4 sec vs. 241.9 sec, p < 0.01), encouraging prolonged engagement with food.
– Body weight: Slight weight loss after relocation, no significant difference across feeding methods.
– Abnormal behavior: Mixed effects:
– One monkey showed reduced stereotypy with the puzzle feeder.
– Another displayed an increase in abnormal behavior.
– Puzzle feeder appeal appeared to be individual-dependent.
While the puzzle feeder did not change total food intake or consistently reduce stereotypic behaviors, it significantly prolonged feeding time, simulating natural foraging behavior. This could be beneficial for behavioral enrichment and health regulation, such as reducing the risk of gastric issues caused by rapid eating. However, individual responses varied, and long-term studies are needed to better assess the puzzle feeder’s effectiveness in promoting welfare.
