A comparison of fecal steroid metabolite concentrations between harem and bachelor stallions in a free-Ranging population of przewalski's horses (Equus ferus przewalskii).

The aim of this study was to determine whether concentrations of reproductive steroid hormone metabolites significantly differed between harem stallions and bachelor stallions in the free ranging group of Przewalski's horses (Equus ferus przewalskii) at the Hortobágy National Park in Hungary. Throughout the study, fecal samples were collected from 21 harem stallions and 15 bachelor stallions and analyzed for immunoreactive estrogen and androgen metabolites. Harem stallions demonstrated significantly higher concentrations of estrogen (P < 0.001) and epi-androsterone (P < 0.001), but not testosterone (P = 0.426). These findings confirm that sociosexual status has a significant effect on androgen concentrations in individual Przewalski stallions. Zoo Biol. 36:127-131, 2017. © 2017 Wiley Periodicals, Inc.