Fecal progesterone metabolite dynamics in relation to reproductive status in captive female golden snub-nosed monkeys...

The golden snub-nosed monkey (Rhinopithecus roxellana) is an endangered primate endemic to China, for which captive breeding is a vital conservation strategy. However, effective management is hindered by the difficulty in detecting pregnancy. This study evaluated fecal progesterone metabolite (fPM) profiles and investigated factors associated with fPM concentrations in six captive females. fPM concentrations showed a gestational rise followed by a rapid postpartum decline. In this dataset, pregnant observations ranged from 217.91 to 4280.91 ng/g, whereas non-pregnant observations ranged from 2.75 to 132.36 ng/g. These ranges are specific to the assay and animals examined in this study and are not proposed as diagnostic cutoffs. A linear mixed-effects model showed significant effects of reproductive status and season, but the reproductive status × season interaction was not significant. Exploratory analyses suggested higher fPM concentrations in adult than in subadult females, whereas parity was not significantly associated with fPM concentrations. These findings indicate that repeated fPM measurements can provide supplementary information for reproductive management in captive R. roxellana, with broader longitudinal sampling needed to refine interpretation across individuals and reproductive stages.