Thomas B. Hildebrandt1, DVM; Guido Fritsch1, DVM; Robert Hermes1, DVM; Katharina Jewgenow1, PhD; Michael Rudolph1, PhD; Julia Maltzan2, DVM; Henning Wiesner2, DVM; Nancy C. Pratt3, PhD; Don Neiffer3, DVM; Dennis L. Schmitt4, DVM, PhD; Frank Göritz1, DVM
Abstract
In general, the reproductive rate of elephants in captivity is low. This is partly because of logistic difficulties associated with transporting these large animals for breeding purposes and there may be physiologic problems which also contribute to this low reproductive rate. In context with a reproductive assessment1 of potential breeding bulls it appears that many adult bulls of both species (Loxodonta africana and Elephas maximus) are not producing viable sperms and/or sufficient ejaculate. Our current understanding of incomplete sexual maturation or temporary infertility in male elephants is at best fragmentary.2,3 The following study was performed for characterizing the physiologic sexual maturation process in young male elephants. Two adolescent individuals of both species have been examined in order to investigate the time of their sexual maturity. The examination utilized transrectal ultrasonography of the urogenital tract, rectal stimulation for the collection of ejaculates as well as blood samples for plasma testosterone determination. The development of the testes, the accessory glands (especially the ampullae), the concentration of the testosterone, the body-height and the success of ejaculation after manual stimulation3 was documented and evaluated over a 3-yr period. The results were compared with data from other adult bull elephants which had ultrasonographic examinations or post mortem investigations.2 The findings of this study led to important conclusions about the characterization of the reproductive status of male elephants by means of ultrasonographic examinations. We established criteria for reproductive soundness in connection with the recruitment of potential semen donors for future artificial insemination projects. The ultrasonographic examination combined with the semen collection were appropriate methods for characterizing the exact state of sexual maturity or for identifying potential reproductive disorders in male elephants.
Acknowledgments
The authors are grateful for the assistance from the elephant staff of the Pittsburgh Zoo, the Muenich Tiergarten Hellabrunn and the Disney’s Animal Kingdom for training the male elephants to stand for the ultrasound examination and semen collection. The authors thank the zoo veterinarians Willem Schaftenaar from the Rotterdam Zoo, Reinhard Göltenboth and Andreas Ochs from the Zoological Garden Berlin for their contributions to our study.
Literature Cited
1. Hildebrandt, T.B., F. Göritz, N. C. Pratt, D. Schmitt, J.L. Lehnhardt, R. Hermes, S. Quandt, J. Raath, G. West, and R.J. Montali. 1997. Assessment of health and reproductive status in African and Asian elephants by transrectal ultrasonography. Proc. Annu. Meet. Am. Assoc. Zoo. Vet. 207–213.
2. Hildebrandt, T.B., F. Göritz, N.C. Pratt, D.L. Schmitt, S. Quandt, J. Raath, and R.R. Hofmann. 1998. Reproductive assessment of male elephants (Loxodonta africana and Elephas maximus) by ultrasonography. J. Zoo Wildl. Med. 29: 114–128.
3. Schmitt, D.L. and T.B. Hildebrandt. 1998. Manual collection and characterization of semen from the Asian elephant (Elephas maximus). Anim Reprod Sci, 53: 309–314.