Core body temperature is not a reliable parameter to follow the reproductive cycle in female marmoset monkey (Callithrix jacchus)

Abstract. Marmosets represent an attractive and widely used animal species in biomedical research, and the routine monitoring of female reproductive cycles is often mandatory in the fields of reproductive biology and stem cell research. Today, the established method for the reliable detection of ovulation is the determination of progesterone concentrations from blood samples. This method is based on relatively frequent handling and blood collections; therefore, less invasive alternatives would help to reduce stress on the animals. Here, we investigated whether the core body temperature of marmosets would show a correlation with cycle-dependent hormonal fluctuations, as has been described for humans and other primate species. In particular, the objective was to investigate whether the telemetric recording of core body temperature could replace progesterone measurements as a reliable, less invasive method for the detection of ovulation in these animals. Here we show that the core body temperature parameters in female marmosets were characterized by frequent variations, but they were not related to particular days or phases during the reproductive cycle. Therefore, the recording of core body temperature in our controlled standard experimental setting is not an appropriate method to monitor the reproductive cycle in female marmosets, and cannot replace serum progesterone measurement as a state-of-the-art method.