Energy metabolism and thermoregulation in pygmy lorises ( Nycticebus pygmaeus) from Yunnan Daweishan Nature Reserve

Abstract

The pygmy loris ( Nycticebus pygmaeus) is a small prosimian living in Vietnam, Laos, eastern Cambodia and the south part of China. In China it is only found in Pingbian, Hekou, Jinping, Luchun of Yunnan. As N. pygmaeus is seriously threatened by hunting, trade and habitat destruction, it is listed in Appendix II of CITES, and in 2006 the IUCN classified it as “vulnerable”. In order to understand the characteristics of energy metabolism and thermoregulation of N. pygmaeus, the resting metabolic rate (RMR) and body temperature ( T b) at different ambient temperature ( T a) of pygmy lorises, as well as body mass, energy intake, digestable energy intake, digestability and the thermal conductance were measured in captivity. The results obtained mainly are as follows: (1) Pygmy loris feed dry food averaged 12.90 ± 1.02 g/d. They could gain 214.87 ± 16.65 kJ/d from food intake, and earned 200.15 ± 16.36 kJ digestable energy intake per day with 90.13 ± 1.34% of the digestability. (2) The T b at room temperatures was a little low (35.23 ± 0.16 °C) and varied with T a from 25 °C to 35 °C. There was a positive relationship between T b and T a, which was described as: T b = 27.22 + 0.34 T a ( r = 0.880). (3) The resting metabolic rate (RMR) of the pygmy loris was 0.3844 ± 0.0162 mlO 2/g/h, which was 51.91 ± 1.90% of the previous predicted rate by Kleiber (1961) [21]. (4) The average thermal conductance of the pygmy loris ( N. pygmaeus) was 0.0449 ± 0.0031 mlO 2/g/h/°C. These characteristics of energy metabolism and thermoregulation of N. pygmaeus in Yunnan Daweishan Nature Reserve might be considered as the adaptive characteristics to their environment in tropical semi-evergreen forests and secondary forests.