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Critically endangered species reproduced using frozen sperm

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Washington: Scientists have successfully reproduced genetically important offspring using frozen semen from a ferret which died 20 years ago. The sire, “Scarface,” as he is affectionately called by the team, was one of the last 18 black-footed ferrets, a critically endangered species native to North America, to exist in the world in the 1980s.

Eight kits, including offspring of Scarface, were born recently, significantly increasing the gene diversity of this endangered population that a dedicated team is working to recover in the wild.

“Our study is the first to provide empirical evidence that artificial insemination with long-stored spermatozoa is not only possible but also beneficial to the genetic diversity of an endangered species,” said David Wildt, lead author, senior scientist and head of the Centre for Species Survival at The Smithsonian Conservation Biology Institute (SCBI).


“What we’ve done here with the black-footed ferret is an excellent example of how sperm preservation can benefit species recovery programmes,” said Wildt. Over the past several years, the team has been developing assisted reproductive technology like artificial insemination and semen cryopreservation.

Scientists collected semen samples from adult black-footed ferrets that ranged in age from one to six years old. Initially, scientists used fresh semen to artificially inseminate females who failed to naturally mate with males, resulting in 135 kits.

Researchers, led by Rachel Santymire, director of the Davee Center for Endocrinology and Epidemiology at Lincoln Park Zoo, routinely collected and preserved black-footed ferret semen for later use as part of standard operating procedures.

SCBI developed a successful laparoscopic artificial insemination technique for black-footed ferrets. Females are induced ovulators, which mean that mating itself causes the ovary to release its eggs.

SCBI researchers developed a hormone treatment that artificially causes ovulation to occur. Scientists then deposited the male’s fresh or frozen-thawed sperm directly into the female’s uterus. Animal care staff closely monitored potentially pregnant females by taking weight measurements and remote monitoring of the nest boxes via closed-circuit cameras.

During the 2008 breeding season, SCBI scientists used semen samples from four male black-footed ferrets donors that had been frozen for 10 years. “Our findings show how important it is to bank sperm and other biomaterials from rare and endangered animal species over time,” said Paul Marinari, senior curator at the Smithsonian Conservation Biology Institute. The study was published in the journal Animal Conservation.