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7 September 2011 Abnormal Reproductive Patterns in Przewalski's Mares Are Associated with a Loss in Gene Diversity
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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 (r2 = 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.

© 2012 by the Society for the Study of Reproduction, Inc.
C. Wynne Collins, Nucharin S. Songsasen, Mandi M. Vick, Barbara A. Wolfe, Rachael B. Weiss, Carol L. Keefer, and Steven L. Monfort "Abnormal Reproductive Patterns in Przewalski's Mares Are Associated with a Loss in Gene Diversity," Biology of Reproduction 86(2), (7 September 2011).
Received: 4 April 2011; Accepted: 1 August 2011; Published: 7 September 2011

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