[Radiotelemetric studies of the body temperature of white-tufted monkeys (Callithrix jacchus)].

A newly developed telemetry system was used to study deep body temperature (BT) of two adult male common marmosets (Callithrix jacchus). The BT-curves of both monkeys showed a similar clear circadian rhythm with a range up to 3.5 degrees C. At environmental temperature of 28 degrees C (ET) the BT of the monkeys varied in the daytime dependent on their spontaneous activity, with little individual differences between 37.5 degrees C and 39.3 degrees C; at night the BT of the remarkably deeply-sleeping animals decreased to an average at 35.8 degrees C. Elevating ET up to 30 degrees C effected an increase of BT by 0.6 degrees C, both during day and night. On the contrary, reducing ET to 24 degrees C the BT increased only at night, by 0.2 degrees C at ad libitum food intake and 1.0 degrees C at fasting. Measurements of BT by inserted rectal thermometer caused, compared with telemetry, an average at 0.4 degrees C higher values.