title: Abnormal reproductive patterns in Przewalski's mares are associated with a loss in gene diversity.
abstract: The ex situ population of the Przewalski's horse (Equus ferus przewalskii) is not self-sustaining (20% foaling rate), and the demography is skewed toward aging individuals with low gene diversity. We designed the present study to gain a better understanding of the reproductive biology of the Przewalski's mare and to determine whether age and gene diversity influenced reproductive function. Urine samples were collected 3-7 days/wk from 19 mares from May to September, and ultrasound examinations of follicular structures were performed 3 days/wk for 5 wk from May through July in nine individuals. A high proportion of mares exhibited abnormal (endocrine, 5 [26.3%] of 19; follicular, 2 [22.2%] of 9) or acyclic (endocrine, 4 [21.1%] of 19; follicular, 3 [33.3%] of 9) reproductive patterns. In four cyclic mares, estrous cycle length was 25.1 ± 1.2 days, with 12.2 ± 0.9 days of diestrus. Follicles in cyclic mares grew 1.2 ± 0.6 mm per day and ovulated after reaching 40.4 ± 8.9 mm. Mares with a high coefficient of inbreeding excreted reduced levels of mean urinary estrogens (r(2) = 0.476, P < 0.05), but age had no significant impact on reproductive patterns in this population. Overall, these data suggest that long-term genetic management of this population is necessary to maintain reproductive fitness.
authors: Smithsonian Conservation Biology Institute, Front Royal, Virginia, USA. w.collins@uq.edu.au
authors: C Wynne
authors: CW
authors: Collins
authors: Nucharin S
authors: NS
authors: Songsasen
authors: Mandi M
authors: MM
authors: Vick
authors: Barbara A
authors: BA
authors: Wolfe
authors: Rachael B
authors: RB
authors: Weiss
authors: Carol L
authors: CL
authors: Keefer
authors: Steven L
authors: SL
authors: Monfort
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D004967:Estrogens / Q000652:urine; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D014644:Genetic Variation / Q000235:genetics* / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D007178:Inbreeding; D007247:Infertility, Female / Q000235:genetics* / Q000503:physiopathology*; D008986:Mongolia; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology; D010060:Ovulation / Q000502:physiology; D011372:Progestins / Q000652:urine; D012098:Reproduction / Q000235:genetics* / Q000502:physiology*; D014463:Ultrasonography
chemical_list: D004967:Estrogens; D011372:Progestins