Seasonal changes in ovarian steroid hormone concentrations in the large hairy armadillo (Chaetophractus villosus) and the crying armadillo (Chaetophractus vellerosus)

Abstract

Knowledge of armadillo reproductive physiology is essential for developing ex situ and in situ assisted reproductive techniques for propagating and/or controlling populations of these animals. The present study included assessment of fecal sex steroids by radioimmunoassay, determining reproductive status via monitoring ovarian activity (in the wild) and therefore reproductive status, in wild females of the large hairy armadillo (Chaetophractus villosus) and the crying armadillo (Chaetophractus vellerosus) in the southern hemisphere. Plasma and fresh fecal progesterone concentrations were not significantly correlated in either species. However, in both species, there was a significant positive correlation between plasma progesterone and dry fecal progesterone concentrations (r 0.82, P 0.05 and r 0.60, P 0.05, respectively). Dry fecal progesterone and estradiol concentrations were measured in one captive C. villosus (average baseline progesterone and estradiol concentrations 28.72 11.75 ng/g dry feces and 3.04 0.80 ng/g dry feces, respectively) and one captive C. vellerosus (average baseline progesterone and estradiol concentrations 14.05 3.03 ng/g dry feces and 3.46 1.20 ng/g dry feces, respectively) to detect hormonal peaks over 1 y; these occurred from late fall to early summer. Feces from wild C. villosus and C. vellerosus were also collected over 1 y to determine progesterone peaks, which occurred in winter and spring in both species (with no peaks during the summer or fall). Accordingly, C. villosus and C. vellerosus had a seasonal reproductive pattern. The significant correlations between dry fecal and plasma progesterone concentrations validated this method for monitoring reproductive status in these species.