Reproductive Seasonality, Estrous Cycle, Pregnancy, and the Recurrence of Postpartum Estrus Based on Long-Term Profiles of Fecal Sex Steroid Hormone Metabolites regarding Zoo-Housed Female Golden Takins (<i>Budorcas taxicolor bedfordi</i>)

This study investigates the non-invasive monitoring of the endocrine ovarian activities of captive female golden takins (<i>Budorcas taxicolor bedfordi</i>) based on long-term fecal sex steroid hormone metabolite dynamics. Fecal progesterone (P₄) metabolite dynamics were monitored in nine females for 0.5–15 years between 2004 and 2022. Fecal estradiol-17β (E₂) and estrone (E₁) metabolites were measured during certain estrous cycles, and fecal E₁ metabolite concentrations were measured during all gestation periods. The breeding season of the captive animals was mainly between May and December, and they were polyestrous animals whose breeding season begins during the long-day period. The onset of the breeding season occurred slightly earlier as age increased. The mean age (±SD) at puberty based on fecal P₄ metabolite dynamics was 4.1 ± 2.9 years. The first conception ages ranged from 2.3–10.2 years. The mean estrous cycle period (±SEM) was 25.4 ± 1.1 days, and mounting and mating occurred in periods of low fecal P₄ metabolite levels during the breeding season. The mean gestation period (±SD) from the estimated mating date to the calving date was 253.9 ± 5.7 days, and the fecal P₄ metabolite distribution during pregnancy was bimodal. Fecal estrone metabolite levels gradually increased 21 weeks before delivery, peaked during the week of delivery, and then markedly decreased in the first week after delivery. Estrus resumed in the first April–August period after delivery (mean ± SD; 103.5 ± 40.9 days) or in May of the year after delivery (421.0 ± 16.5 days). This study revealed that the estrous cycle and pregnancy of female golden takins can be determined by fecal progesterone metabolite dynamics and that fecal estrone metabolite dynamics increases toward parturition and are useful for predicting the date of delivery. This endocrinological information is important for planned breeding efforts for the golden takins.