Monitoring sexual steroids and cortisol at different stages of the ovarian cycle from two capuchin monkey species: use of non- or less invasive methods than blood sampling.

Endocrine monitoring of non-human primates (NHP) via faecal metabolites of steroid hormones appears as a useful non-invasive alternative to evaluate the reproductive status of free living NHP, as well as of those kept in captivity but of difficult handling. However, validation is needed with plasma values before its application in the field. The aim of the present study was to monitor the different phases of the menstrual cycle from the new world NHP and For this, hormonal and faecal plasma levels of E, P and cortisol were assessed during different days of the menstrual cycle, together with colpocitology. The mean duration of the menstrual cycle according colpocitology was of 21.7 and 21.0 days for and respectively. These values were similar to those observed via plasma analysis, i.e. 22.7 and 20.3 days for and respectively. The day of plasmatic E peak was set as Day -1 and the estimated day of ovulation was set as Day 0 and occurred two days earlier in than in females. In both species, it was observed a delay in faecal E peak of six days for and of 11 days for when compared with the plasma peak. A maximum P plasma concentration was observed in the middle of luteal phase in and in both at around day 5 However, faecal P peaks were detected at days 9 and 8 in and , respectively. Mean plasma and faecal cortisol levels were variable during all ovulatory cycle of and females. Although no exact correlation was observed between plasmatic and faecal profile of steroid hormone, faecal samples were able to indicate ovarian cycle phase, being important to assess the reproductive status of the females applying a non-invasive method.