Effects of seasonal changes in dietary energy on body weight of captive Japanese macaques (Macaca fuscata).

Food availability varies seasonally for wild animals, and body weight fluctuates accordingly in the wild. In contrast, controlling availability of diet under captive condition is difficult from keepers' standpoint, and monotonous diet often causes health problems in captive animals. We evaluated the effects of a seasonally controlled diet on body weight of captive Japanese macaques (Macaca fuscata) in an outside enclosure at Ueno Zoo, Tokyo, Japan. We fed a high-energy diet in spring and fall, and a more restricted diet in summer and winter for 3 years (2011-2013). Seasonal changes in body weight were similar to those that occur in wild macaques: for both sexes, body weight was higher in spring and fall and lower in winter. A decrease in body weight between fall and winter occurred only in adults, which implied that reducing dietary intake in winter had a more severe effect on adults than on juveniles. Different from wild populations, the body weight of captive macaques did not decrease between spring and summer, which we attributed to a lack of movement within the enclosure and to excess energy intake in summer. In addition to controlling dietary composition, providing large enclosure with complex structure and making efforts of giving unpredictability in feeding are necessary to motivate the captive animals to be more active, which would cause the macaques to show seasonal change in body weight, which is found in wild.