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.
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7 September 2011
Abnormal Reproductive Patterns in Przewalski's Mares Are Associated with a Loss in Gene Diversity
C. Wynne Collins,
Nucharin S. Songsasen,
Mandi M. Vick,
Barbara A. Wolfe,
Rachael B. Weiss,
Carol L. Keefer,
Steven L. Monfort
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Biology of Reproduction
Vol. 86 • No. 2
February 2012
Vol. 86 • No. 2
February 2012
donkeys
endocrinology
equids (horses
estrous cycle
female infertility
follicular patterns
Genetics