Reproductive Seasonality and Pregnancy Based on Fecal Steroid Hormone Dynamics in Zoo-housed Chamois (Rupicapra rupicapra)

Abstract

　 The objective of this study was to determine the reproductive physiology of captive chamois (Rupicapra rupicapra), including the breeding season and estrous cycle, based on fecal steroid hormone dynamics. We collected fecal samples from two male and one female chamois and quantified fecal testosterone (T) and androstenedione (AD) concentrations in males and progesterone (P4), estradiol-17β (E2), estrone (E1), and cortisol concentrations in the female using enzyme immunoassays. Fecal T and AD concentrations in males showed similar annual variations. Fecal T and AD concentrations in males started to increase in April or May and decreased in November or December when the female estrous cycle resumed. Male to female following, mounting, and copulation were observed during periods of low P4 concentrations in the estrous cycle. The length of the estrous cycle based on P4 dynamics was an average of 23.0 days. The female was already pregnant at the beginning of the present study (79 days before parturition). Fecal P4 concentrations remained high and markedly decreased on the day before parturition. The estrous cycle recurred 195 days after parturition. Fecal E2 and E1 concentrations during pregnancy showed similar high fluctuations. Fecal cortisol concentrations during pregnancy markedly increased approximately 40 days before parturition, remained high until the day before parturition, and then immediately decreased on the day after parturition. The present results revealed that the chamois is polyestrous short-day seasonal breeding animal based on fecal sex steroid dynamics. Furthermore, the measurement of fecal P4, E2, and E1 concentrations in females is useful for the diagnosis and monitoring of pregnancy.