Hormonal monitoring of age at sexual maturation in female Goeldi's monkeys (Callimico goeldii) in their family groups.

The aim of this study was to determine whether or not sexual maturation is attained in the family group in captive-born Goeldi's monkey (Callimico goeldii) and if so, at what age and body weight. To monitor ovarian activity in 14 female Goeldi's monkeys, urinary content of pregnanediol-3alpha-glucuronide (PdG) was determined using radioimmunoassay. Urinary samples were collected between the ages of 6 and 70 weeks. Subjects became sexually mature while still housed in their family groups, at a median age of 57 weeks (48-< 70 weeks). Median body weight at the age of sexual maturity was 473 g (N=10; 420-543 g). This corresponded to 90% of the median non-pregnant body weight of breeding females in our colony (526 g, N=8). Therefore, Goeldi's monkey is similar to Leontopithecus but different from Cebuella, Callithrix, and Saguinus, in terms of daughters ovulating in the family group and at a relatively young age.