Research articlePuberty, ovarian cycle, pregnancy, and postpartum ovulation in captive Sichuan golden monkeys (Rhinopithecus roxellana) based on changes in urinary and fecal gonadal steroid metabolites

The purpose of this study was to evaluate the reproductive status and clarify the reproductive physiology of captive Sichuan golden monkeys. The concentrations of urinary estradiol-3-glucuronide (E2G) and pregnanediol-glucuronide (PdG) or fecal estradiol-17β (E2) and PdG in two females, and fecal testosterone concentrations in a male, were measured continuously using enzyme immunoassays. On the basis of these hormone profiles, the follicular phase, luteal phase, and ovarian cycle were calculated to be 14.7 ± 4.8, 10.4 ± 2.8, and 25.1 ± 3.3 days, respectively. The first ovulation (puberty) in a female monkey was observed at 5.1 years old, and the first pregnancy was diagnosed at 6.4 years old. For the first 2 months of pregnancy (204 days), fecal E2 and PdG maintained constant high values and then increased until parturition. These profiles were similar to urinary E2G and PdG changes. During the last trimester of a twin pregnancy, fecal PdG was up to approximately three times higher compared with a single pregnancy. Therefore, fecal PdG levels in late pregnancy may be effective for the detection of a twin pregnancy. The first postpartum ovulation occurred 66 (fetal death and artificial rearing), 143 (fetal death), and 189 (natural suckling) days after parturition. The anovulation period of the natural suckling case was longer than the others. Conception and postpartum ovulation were detected between September and January. Fecal testosterone levels of the male were correlated with the fecal E2 level of the nonpregnancy period in exhibited together female. Our results reported that urinary (E2G and PdG) and fecal (E2 and PdG) hormone measurement is effective for monitoring the reproductive status, thereby expanding knowledge of the reproductive endocrinology of this endangered species.