Survey of the reproductive cyclicity status of Asian and African elephants in North America
Publication Type: |
Journal Article |
Year of Publication: |
2004 |
Authors: |
Janine L. Brown, Deborah Olson, Mike Keele, Elizabeth W. Freeman |
Publication/Journal: |
Zoo Biology |
Publisher: |
A Wiley Company, Inc., Wiley Subscription Services |
Keywords: |
hormones, ovarian cyclicity, progestagens, reproductive dysfunction, ultrasound |
ISBN: |
1098-2361 |
Abstract:
The Asian and African elephant populations in North America are not self-sustaining, and reproductive rates remain low. One problem identified from routine progestagen analyses is that some elephant females do not exhibit normal ovarian cycles. To better understand the extent of this problem, the Elephant TAG/SSP conducted a survey to determine the reproductive status of the captive population based on hormone and ultrasound evaluations. The survey response rates for facilities with Asian and African elephants were 81% and 71%, respectively, for the studbook populations, and nearly 100% for the SSP facilities. Of the elephants surveyed, 49% of Asian and 62% of African elephant females were being monitored for ovarian cyclicity via serum or urinary progestagen analyses on a weekly basis. Of these, 14% of Asian and 29% of African elephants either were not cycling at all or exhibited irregular cycles. For both species, ovarian inactivity was more prevalent in the older age categories (>30 years); however, acyclicity was found in all age groups of African elephants. Fewer elephant females (∼30%) had been examined by transrectal ultrasound to assess reproductive-tract integrity, and corresponding hormonal data were available for about three-quarters of these females. Within this subset, most (∼75%) cycling females had normal reproductive-tract morphologies, whereas at least 70% of noncycling females exhibited some type of ovarian or uterine pathology. In summary, the survey results suggest that ovarian inactivity is a significant reproductive problem for elephants held in zoos, especially African elephants. To increase the fecundity of captive elephants, females should be bred at a young age, before reproductive pathologies occur. However, a significant number of older Asian elephants are still not being reproductively monitored. More significantly, many prime reproductive-age (10–30 years) African females are not being monitored. This lack of information makes it difficult to determine what factors affect the reproductive health of elephants, and to develop mitigating treatments to reinitiate reproductive cyclicity.