Center of Excellence in Elephant and Wildlife Research, CMU

ศูนย์ความเป็นเลิศด้านการวิจัยช้างและสัตว์ป่า มช.

Elephant Reproduction

Elephant reproduction is a very important topic that is very nessessory for elephant conservation. Understanding about anatomy, physiology and pathology can improve the conservation strategy for long term conservation. In this section, it consists of 2 main topics, which are;

Male Elephant Reproduction

Nikorn Thongtip D.V.M.,M.Sc., Ph.D.
Faculty of Veterinary Medicine
Kasetsart University, Thailand

The male elephant reproduction study are still going on. The most remarkable difference from other mammal species is the intra-abdominal testicles, which can weigh up to 2 kg each in an adult bull (Figure 1 and 2). The elephant has all accessory sex glands that has been characterized for most mammalian species: i.e., bulbo-urethral glands, prostate, seminal vesicles, and ampullae (Hildebrandt et al., 2000). The transrectal ultrasonography was useful for evaluating the accessory glands strctures (Figure 3). Asian elephant semen collection is used manual collection technique which has been described by Schmitt and Hildebrandt (1998) (Figure 4). The Asian elephant spermatozoa has the same morphology or structure with another mammalian species (Figure 5). The successful production of live calves after AI with fresh semen in the Asian elephant were demonstrated (Schmitt et al., 2001; Brown et al., 2004; Thongtip et al., 2009). Although acceptable post-thaw survival has been reported (Thongtip et al., 2004; Sa-ardrit et al., 2006). The birth of live calve after AI with frozen-thawed semen in the Asian elephant has never been reported. There is only one report about the pregnant of female Asian elephant by using frozen-thawed semen in Thailand (Thongtip et al., 2009). Unlucky, the full term fetus was abort and expelled during seventeen month of gestation (Thongtip et al., 2009). One of the major obstacles in developing an effective method to cryopreserve Asian elephant spermatozoa is the variation in semen quality of ejaculates obtained from the same or different individuals. A majority of semen samples obtained by manual stimulation exhibit poor quality (i.e., low motility) (Thongtip et al., 2001; 2004), of which the cause has not been cleary determined. Our previous reported found that a total of seventy semen samples obtained weekly from 20 Thai,s domesticated elephants (age medians were 19.5 year old) using manual collection technique over the period of five months revealed 0% medians of progressive motility. The clearing of these phenomenon is under investigating.

Figure 1. Anatomy of Asian Elephant testis

Figure 2. Transrectal ultrasonography of Asian elephant accessory glands

Figure 3. Semen collection by manual collection technique

Figure 4. Spermatozoa of Asian elephant

Female Elephant Reproduction

Chatchote Thitaram, D.V.M., Ph.D.
Faculty of Veterinary Medicine
Chiang Mai University, Thailand

The normal estrous cycle of the female Asian elephant is between 14 and 18 weeks in length with pregnancy lasting 20-22 months. The non-pregnant luteal phase, characterized by high circulating progestagen concentrations, ranges between 10-14 weeks, while the interluteal phase (or follicular phase) lasts between 3 and 6 weeks. During the follicular phase, 2 surges (peaks) of luteinizing hormone (LH) release occur. The first LH surge is anovulatory (anLH), whereas ovulation occurs three weeks later around 24 hours after the second LH (ovLH) surge. Although the changes in reproductive hormones during the cycle have been described, the unique double LH surge mechanism is still not understood. Particularly the function of the anLH surge is puzzling, while the ovLH surge is known to induce ovulation. A female only has three chances per year to conceive. Within each cycle, the fertile period can be considered to be from 2 days before, until shortly after the ovulation. Therefore, identification of this brief period is most critical to ensure that males breed females at the proper time. Several methods have been developed to characterize the estrous cycle in Asian elephants; for instance, by observation of reproductive behaviors or the monitoring of serum and urinary estrogen and progesterone or their derivatives. Most of the reproductive cycle studies in elephants include estimations of progestagens, the major one being 5-pregnane-3,20-dione (5-DHP). Progestagen profiles were used to determine the onset of the luteal phase, which approximately indicates the ovulation period, as progestagens increase 2-3 days before the ovLH surge, and ovulation occurs approximately 24 hours after the ovLH. Progestagen profiles can also be used for pregnancy diagnosis characterized by continuous elevated concentrations of progestagens over a 3-5 months period at double the concentrations encountered during the normal luteal phase of the ovarian cycle.

Figure 1.Estrous cycle of the elephant. Elevated progestagens indicate the luteal phase. When progestagens return to baseline, the follicular phase begins. Two follicular waves occur with high estradiol concentrations associated with non-ovulated multiple follicles prior to the anLH surge and, 3 weeks later, one Graafian follicle prior to the ovLH surge are observed. Ovulation occurs approximately 24 hours after the ovLH surge, with a subsequent increase of progestagen concentration due to the steroidogenic activity of the corpus luteum. (Thitaram 2009; PhD thesis, Utrecht University, TheNetherlands)

Figure 2. Ovary of female elephant. Several small follicles were observed on the ovary.