Abstract
Asian elephant (Elephas maximus) populations are not self-sustaining in captivity, and in Japan there have been only three cases of successful parturition, including two reported in this study. To improve the reproductive performance of this species, an understanding of Asian elephant reproductive physiology and developing assisted breeding techniques are required. In particular, the techniques used to diagnose and monitor pregnancy and to predict parturition are crucial. During three pregnancies, including a stillbirth, progestin levels in plasma of a female Indian elephant, kept at the Kobe Municipal Oji Zoo, were measured using a rapid enzyme immunoassay system without extraction. Similar progestin profiles were observed in the three pregnancies. During the first 9 weeks of each conception, rising of progestin to a peak similar to those of regular estrus cycles was observed, progestin levels decreased thereafter, but not to a baseline, and then increased. This hormone level change might be useful to predict pregnancy in Asian elephants. Subsequently, during mid- to late-pregnancy, progestin levels showed a bimodal pattern declined in the middle and then increased slightly again. During the late portion of the third observed pregnancy, daily measurement of progestin in fresh plasma samples showed a rapid decrease to a baseline level four days prior to the parturition. The zoo elephant keepers could predict subsequent parturition.
