Endocrine characterization of female reproductive status in wild redfronted lemurs (Eulemur fulvus rufus)

In order to characterize the endocrine changes associated with ovarian function and pregnancy in wild redfronted lemurs (Eulemur fulvus rufus), profiles of immunoreactive 5alpha-pregnane-3alpha-ol-20-one (5-P-3OH) and total estrogens (E(t)) in feces were generated during the breeding season and gestation. HPLC data confirmed the presence of high amounts of 5-P-3OH in the feces of redfronted lemurs and showed that estrone and estradiol-17beta were the major estrogens excreted into feces, with estrone predominating. Due to an extreme day-to-day variability in excretion of both hormones during the breeding season, estrus cycle characterization was not possible for the free-ranging females. Comparison with endocrine data from captive animals suggested that this might have been associated with a highly variable amount of undigested fecal matter in the feces of wild females. A gestation length of 121.3 days was calculated on the basis of the day of behavioral estrus and date of parturition. Hormonally, pregnancy could be reliably diagnosed from day 40-45 after conception, when fecal progestogen levels clearly increased above breeding season concentrations in all females. Levels gradually increased thereafter, with 15- to 35-fold elevated maximum levels being reached shortly before parturition. In contrast, the pattern of fecal estrogen excretion was strongly related to the sex of the fetus in utero, with only females carrying male infants showing elevated (25- to 50-fold) estrogen levels during the last third of gestation, while levels remained at low breeding season levels in female-carrying mothers. Thus, fecal estrogen measurements during the last 6-7 weeks of gestation allow fetal sex to be determined prenatally. By providing the first data on the reproductive endocrinology of E. fulvus, we have shown that fecal hormone analysis is a useful tool to monitor endocrine changes associated with pregnancy, while it appears to have certain limitations regarding the assessment of ovarian function.