Abstract: Two adult female Asian elephants at the Beijing Zoo are not known to have ever come into estrus. In order tounderstand possible reasons for this,we studied variation in urinary estradiol and progesterone levels of these 2 non-oestrus females,as well as of a pregnant female at the zoo,via radioimmunoassay from December 2003 to March 2005. For the pregnant female, progesterone increased abruptly one week before parturition and remained at a low level afterwards. Estradiol began at a high level,decreased suddenly one week before parturition, and remained at a low level until the end of the study. Urinary progesterone and estradiol levels in the non-estrus elephants was notably lower than in the pregnant elephant, and displayed no obvious periodic fluctuation. We hypothesize that ovaries in these 2 elephants were inactive, resulting in lack of hormone fluctuation and lack of estrous.

Key words: Asian elephant (Elephas maximus), Female hormone, Ovarian inactivity

摘要： 针对北京动物园2 头圈养雌性亚洲象从未动情的现象,本研究于2003 年12 月至2005 年3 月,采用放射性免疫分析法测定了2 只不动情象与另一只已受孕象尿液中孕酮和雌二醇的变化,并结合国内外研究探讨圈养亚洲象不动情的原因,为圈养象机构提供相应的繁殖管理建议。研究结果表明,受孕雌象在分娩前一周左右孕酮含量突然升高,后在很短时间内降低,分娩后也维持在较低水平;雌二醇含量分娩前维持在较高水平,分娩前一周骤降,并保持较低水平至本研究结束。非动情象尿液中孕酮和雌二醇水平都显著低于受孕象相应的激素水平,且无明显的波动,推测其卵巢不具活性,导致孕酮与雌二醇水平不具波动性,是这2 头圈养雌象未见动情现象的主要原因。

关键词: 亚洲象, 雌性激素, 卵巢不活动性