<a name="home"></a>Fecal estradiol and progesterone metabolite levels in the three-toed sloth (Bradypus variegatus)

Abstract

The present study was carried out to assess the possibility of measuring fecal steroid hormone metabolites as a noninvasive technique for monitoring reproductive function in the three-toed sloth, Bradypus variegatus. Levels of the estradiol (E 2 ) and progesterone (P 4 ) metabolites were measured by radioimmunoassay in fecal samples collected over 12 weeks from 4 captive female B. variegatus sloths. The validation of the radioimmunoassay for evaluation of fecal steroid metabolites was carried out by collecting 10 blood samples on the same day as defecation. There was a significant direct correlation between the plasma and fecal E 2 and P 4 levels (P < 0.05, Pearson's test), thereby validating this noninvasive technique for the study of the estrous cycle in these animals. Ovulation was detected in two sloths (SL03 and SL04) whose E 2 levels reached 2237.43 and 6713.26 pg/g wet feces weight, respectively, for over four weeks, followed by an increase in P 4 metabolites reaching 33.54 and 3242.68 ng/g wet feces weight, respectively. Interestingly, SL04, which presented higher levels of E 2 and P 4 metabolites, later gave birth to a healthy baby sloth. The results obtained indicate that this is a reliable technique for recording gonadal steroid secretion and thereby reproduction in sloths.

Characterization of the ovarian cycle in the two-toed sloths (Choloepus didactylus): An innovative, reliable, and noninvasive method using fecal hormone analyses

“…The defecation rate averaged around twice a week, which is similar to the cycles of the three-toed sloth [9]. Despite, in our pilot study we were able to confirm the independence of hormone concentrations from influences such as defecation cycles and storage times [21].…”

“…Although Mühlbauer [9] determined an estrous cycle of >60 days in one female three-toed sloth, we choose to use P 4 analysis as it provides the most reliable data on the determination of the ovarian cycle length. We detected a defined duration of the cycle ranging from 31 days (at the level of lowest P 4 ) to 33 days (at the level of highest P 4 ).…”

“…In an initial investigation to study the reproductive endocrinology, Gilmore et al [8] in 1991 have collected plasma samples of one captured pregnant female three-toed sloth (Bradypus tridactylus) and determined the basal serum levels of estradiol and progesterone by radioimmunoassay (RIA). About 15 years later, Mühlbauer et al [9] first published the fecal hormone concentrations in the three-toed sloth. However, the transferability between the two families of sloths is complicated due to differences in the seasonality and the period of gestation [7].…”

First observation on mating and reproductive seasonality in maned sloths Bradypus torquatus (Pilosa: Bradypodidae)

“…It is also essential to investigate endocrine aspects, including the control of spermatogenesis and oestrous cycles, since only with this information can we form a definite view of B. torquatus reproduction. In this sense, results from a recent study (Mühlbauer et al 2006) are encouraging. These authors demonstrated that it is possible to follow the hormone cycles of male and female sloths (Bradypus varieagatus) through the monitoring of faecal samples by noninvasive techniques.…”

Citologia vaginal de preguiça-de-coleira (Bradypus torquatus)

“…Na preguiça-comum, Bradypus variegatus, verificou-se através de dosagem de estrógeno e progesterona nas fezes que a duração do ciclo estral é de mais ou menos 60 dias, com formação de corpo lúteo funcional após ovulação (Mühlbauer et al 2006), o que sugere que as preguiças-de-coleira também apresentem um ciclo estral longo. Este pode ser o motivo da variação entre as porcentagens de células do epitélio vaginal entre os animais utilizados.…”