Survey of the reproductive cyclicity status of Asian and African elephants in North America

Abstract

The Asian and African elephant populations in North America are not selfsustaining, 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 (B30%) 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 (B75%) 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.

Fecal 20-oxo-pregnane concentrations in free-ranging African elephants (Loxodonta africana) treated with porcine zona pellucida vaccine

“…Previous studies already documented alternation between cyclic and non-cyclic periods as well as erratic progestagen secretion in untreated African elephant populations [27,55]. Furthermore, most data on wild populations have been unable to determine continuous cyclicity status, as in the majority of cases, the subjects already are or become pregnant during the course of the study [26][27][28]. Interpreting causes for irregular or non-cyclic patterns of progestagen secretion in African elephants is fraught with complexity given a vast variety of potential influences such as an individual's social status, body condition, climatic and seasonal influences [26,29,55].…”

“…Furthermore, our results demonstrate that in the two years following pZP treatment at TPNR, estrous cycles are present amongst nearly half of treated individuals, indicating ovarian functionality. Previous studies already documented alternation between cyclic and non-cyclic periods as well as erratic progestagen secretion in untreated African elephant populations [27,55]. Furthermore, most data on wild populations have been unable to determine continuous cyclicity status, as in the majority of cases, the subjects already are or become pregnant during the course of the study [26][27][28].…”

“…However, the knowledge acquired regarding the reproductive endocrinology of the African elephant is predominantly from studies on captive individuals. Amongst wild populations, the information gleaned regarding estrous cycles has been inconclusive due to the common occurrence of pregnancy or lactation among females [26][27][28].…”

“…However, the knowledge acquired regarding the reproductive endocrinology of the African elephant is predominantly from studies on captive individuals. Amongst wild populations, the information gleaned regarding estrous cycles has been inconclusive due to the common occurrence of pregnancy or lactation among females [26][27][28].Monitoring luteal endocrine function via faecal hormone analysis has made it possible to examine the reproductive biology of wild and captive animals [1,18]. Faecal samples can be easily collected and non-invasive methods have already been developed and successfully tested to enable the measurement of progestagen metabolites in elephant faeces [22,29].…”

Early primary-rather than primordial follicles constitute the main follicular reserve in the African elephant (Loxodonta africana)

“…For the management of the African elephant (Loxodonta africana), methods of contraception as well as assisted breeding are required (Brown et al, 2004;Delsink, 2006). The duration of the female elephants reproductive life is about 50 years (Perry, 1953;Freeman et al, 2009).…”