Study of fecal progesterone metabolites in captive and reintroduced bantengs (Bos javanicus birmanicus) in Kanchanaburi, Thailand

Understanding species’ reproductive biology is important for animal propagation, and the non-invasive technique of measuring fecal progesterone is a useful method for assessing reproductive health in wildlife. In this study, ovarian cycles of the captive bantengs and reproductive health of the reintroduced individuals were evaluated by assessing fecal hormone metabolites. A year-round examination of the ovarian cycles of four female bantengs (Bos javanicus birmanicus) housed ex situ was conducted by fecal progesterone metabolites detection. Furthermore, the means of fecal progesterone level were compared between females housed under human care and reintroduced individuals. Results revealed year-round estrous cycles in ex-situ females, unless interrupted by pregnancy. Average fecal progesterone metabolites (mean ± standard error of mean [SEM]) during the luteal phase of the four females (F1, F3, F4 and F8) were 1227.42 ± 167.45, 385.80 ± 46.55, 632.59 ± 44.19, and 872.4 ± 136.8 ng/g of dry feces, with average estrous cycle intervals of 21.14 ± 1.17 days. Mean baseline concentrations of fecal progesterone metabolites were 594.35 ± 422.59, 93.12 ± 51.71, 216.90 ± 64.92 and 166.17 ± 113.45 ng/g of dry feces, respectively. Mean fecal progesterone levels were approximately 4-fold greater (P < 0.001) during pregnancy than the non-pregnant period (pregnancy: 2399.35 ± 317.27 ng/g; non-pregnancy: 675.31 ± 107.8 ng/g). Mean progesterone concentration was higher (P = 0.028) in reintroduced females than in ex-situ individuals. This study advances the understanding about banteng reproductive biology, information that is critical for assessing reproductive health of both captive and reintroduced populations.