Reproductive management of the Asian elephant (Elephas maximus) is important for its conservation. To monitor its estrous cyclicity, we earlier used an indirect ELISA to show that levels of fecal progesterone (P4)-metabolite (allopregnanolone: 5α-P-3OH) in semi-captive females sampled randomly positively correlated with serum P4 levels . In this longitudinal study (51weeks), we measured levels of fecal 5α-P-3OH and serum P4 in seven semi-captive female elephants. Females exhibited three types of hormonal profiles. Four females showed cyclical patterns of fecal 5α-P-3OH and serum P4 typical of normal estrous cycles, two showed acyclic pattern while one showed high values indicative of a pregnant animal. Values for anestrous or follicular phases were ≤0.3μgg-1 (5α-P-3OH) and ≤0.3ngmL-1 (P4); for luteal phase 0.32-11.09μgg-1 (5α-P-3OH) and 0.32-1.48ngmL-1 (P4); for pregnancy 1.41-7.38μgg-1 (5α-P-3OH) and 0.39-1.6ngmL-1 (P4). A positive correlation (t=8.8, p<0.01, n=321) between levels of fecal 5α-P-3OH and serum P4 was observed. A random sample of 30 free-ranging female elephants showed fecal 5α-P-3OH values of 0.06-23.4μgg-1, indicating them to be in different stages of estrous cyclicity. This study is the first to assess the reproductive phases of female Asian elephants based on the correlative-patterns of both the fecal 5α-P-3OH and serum P4 values over multiple estrous cycles. This has a potential application in the reproductive management and conservation of Asian elephants.
Bibliographical noteFunding Information:
This research was supported by the Ministry of Environment and Forests, Govt. of India, New Delhi. We thank the forest departments of Karnataka and Tamil Nadu states for providing permission to conduct research. We also acknowledge K. Bomman for his help and support in the field and Dr. Kavita Isvaran for her help in the statistical analyses of the data and M.S. Padmavathi in the preparation of the manuscript.