Rare ferrets reproduce with long-frozen sperm

September 3rd, 2008 - 12:14 pm ICT by IANS  

Washington, Sep 3 (IANS) Two ferrets at the Smithsonian’s National Zoo have each given birth to an offspring that was sired by males who died in 1999 and 2000. These endangered ferrets were artificially inseminated in May with frozen semen from the two dead males, each giving birth to a kit (offspring) on June 20 and 21 respectively.

The sperm samples were collected and frozen in 1997 and 1998 as part of a multi-institutional breeding and reintroduction programme. Successful inseminations with frozen semen are extremely rare - until now only three black-footed ferret kits have been born with this method.

The black-footed ferret is one of the most endangered animals in the world. Once inhabiting the grasslands of the western Great Plains, the black-footed ferret population declined with the loss of the North American prairie ecosystem.

Prairie dogs are the ferret’s primary prey, and only two percent of the original prairie dog habitat remains today. A recent outbreak of sylvatic plague (also known as bubonic plague) in a prairie dog population in South Dakota also threatens to decimate ferret populations there.

For more than 10 years, the semen was stored in the Zoo’s Black-Footed Ferret Genome Resource Bank, a repository of frozen semen from the most valuable males.

In species that have short life-spans like the black-footed ferret, the use of cryopreserved, or frozen, sperm extends an individual’s reproductive life. The bank’s contents help maintain and even enhance genetic diversity by infusing new genes into the population.

A genetically healthy and diverse population has a greater chance of survival in the wild. The bank also serves as insurance against catastrophes in the wild populations, such as a disease outbreak.

The National Zoo has played a critical role in black-footed ferret recovery since 1981 when a small population of the species, previously thought to be extinct, was discovered in Wyoming.

The 18 remaining ferrets were removed from the wild to establish a captive breeding and recovery programme in Wyoming. The National Zoo’s Conservation and Research Centre was the first institution outside of Wyoming to breed the species.

Scientists at the National Zoo also developed the first successful artificial insemination technique for the species that deposited sperm directly into the uterus.

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