CORRELATION BETWEEN URINARY PREGNANEDIOL GLUCURONIDE AND BASAL BODY-TEMPERATURE IN FEMALE ORANGUTANS, PONGO-PYGMAEUS

Changes in basal body temperature (BBT) in relation to the menstrual c ycle were investigated in three adult female orangutans (Pongo pygmaeu s). In particular, the relationships of BBT to urinary estrone conjuga tes (EC) and to pregnanediol glucuronide (PDG) were examined using two of the females during two cycles each. Radiotelemetry transmitters we re implanted peritoneally to record core body temperatures. Radio sign als were received approximately every 2 min, 24 h per day. Because tem peratures during the period 0300-0400 h were most stable (i.e., were l ess likely to be affected by confounding variables such as activity), a mean of these values was used to calculate daily BBT. BBT showed a h ighly significant positive correlation with PDG but not with EC. Menst rual phases were associated with declining or trough levels of BBT. Al though changes in BBT were not sufficiently distinct to predict or to precisely identify the time of ovulation, the strong association betwe en BBT and PDG suggests that radiotelemetry of BBT may be useful in mo nitoring ovarian cycles, especially the luteal phase, in this species. (C) 1994 Wiley-Liss, Inc.