Enriching the Genetic Pool and Managing the Sex Ratio of Captive Elephant Populations Through Artificial Insemination with Frozen-Thawed Semen Collected in the Wild
The order Proboscidea contains only one family of living animals—the Elephantidae, which includes the genera Loxodonta with two species - African savannah elephant (Loxodonta africana) and African forest elephant (Loxodonta cyclotis), and Elephas with a single species—Asian elephant (Elephas maximus). Survival of all three elephant species in their native habitats is threatened, particularly that of the Asian elephant that is classified as an endangered species in the International Union for Conservation of Nature and Natural Resources (IUCN) Red List.1,7 The captive zoo elephant population is comprised of approximately 2000 African and Asian elephants.
Until today the captive elephant population is not self-sustaining and with a limited number of breeding bulls, its genetic diversity is in decline. One way to overcome this is to import young and healthy animals from the wild. We introduce here a more sustainable alternative method - importation of semen from wild bulls without removing individuals from their natural habitat. Due to the logistics involved, the only practical option would be to transport cryopreserved sperm which has a calculated shelf life of approximately 3000 years.
The first successful artificial insemination (AI) in an elephant was reported in 1998, using fresh semen. Since then, almost 60 calves have been produced through AI in both Asian and African elephants worldwide. Following these successes, with the objective of enriching the captive population with genetic material from the wild, we evaluated the possibility of using frozen-thawed semen collected from wild African elephant bulls for AI in captivity.9
Under the leadership of the Leibniz Institute for Zoo and Wildlife Research, in close collaboration with ZooParc de Beauval, Pittsburgh Zoo & PPG Aquarium and the National Zoo Pretoria, two semen collection operations (Project Frozen Dumbo I and II) were performed in the Republic of South Africa in 2010 and 2011.5
In 2012, the first elephant AI baby derived from frozen-thawed semen was born in Vienna.6 Since then, four more successful pregnancies were achieved by using cryopreserved semen from the wild.
In general, the incorporation of AI with frozen-thawed semen into the breeding management portfolio opens the way to preserve and transport semen between distant individuals in captivity or between wild and captive populations, without the need to transport stressed or potentially disease-carrying animals or to remove animals from the wild.
In addition, AI in combination with other assisted reproduction technologies such as sperm sex-sorting techniques (Behr et al. 2009; Hermes et al. 2009) provides new opportunities for managing the sex ratio of the offspring.2-4 Housing of bachelor elephant groups becomes a challenging operation in Europe and North America so that a shifted sex ratio in the progeny would be a desired management tool.8
There is a new initiative for a third semen collection operation (Project Frozen Dumbo III) as a joint operation between the European and North American Elephant TAG in the near future.
The authors would like to thank the conservation societies of ZooParc de Beauval, the Pittsburgh Zoo & PPG Aquarium, National Zoo Pretoria and the Tiergarten Schoenbrunn for their logistic and financial support of the project. We also like to thank the staff of the Wuppertal Zoo and African Lion Safari for their help in the field.
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