Effects of gradient photoperiod and temperature on energy metabolism and body composition in Tupaia belangeri Chinensis

In order to explore the adaptive changes in energy metabolism and body composition in response to a gradual reduction in both ambient temperature and photoperiod, male adult tree shrews Tupaia belangeri chinensis were raised under the conditions of 30 oC and 12L:12D photoperiod (control group). The treatment group was changed from 25 oC and 16L:8D photoperiod to 5 oC and 8L:16D photoperiod (treatment group) over a period of four weeks and then maintained at those conditions for a further 4 weeks. Changes in body mass, resting metabolic rates (RMR),energy intake, and wet and dry mass of organs and tissues were measured at the end of the acclimation. Body mass in treatment tree shrews was higher than control. RMR showed significant differences between groups. No significant differences were detected in dry matter intake, energy intake, and digestible energy intake in control tree shrews during the whole acclimation period, while these parameters were significantly increased within treatment tree shrews at the end of acclimation, and were significantly higher than those in control tree shrews. Small intestine and stomach dry mass, as well as the wet mass of small intestine, heart, lung, liver and kidney were significantly higher in treatment groups than in controls, but no significant differences were found in the mass of other organs and tissues. These results suggest that increasing body mass and energy intake, together with adjusting the mass of some organs and tissues, are important physiological changes in tree shrews to adapt the changing environmental conditions.