When the lion awakens, testes and libido intact, he has no idea that the key aspect of his masculinity has been removed, and he continues to behave as king of the pride. The scientists use the sterile lion as a "teaser" to determine which females are "in season" and ready to inseminate.
Slow Route to Success
Lions are exhaustive maters, mating every 12 to 15 minutes for up to five days.
The frequency of mating, researchers speculate, is meant to stimulate egg release in the female. Only after a "teaser" has stimulated the female can she be successfully inseminated with sperm from an unrelated male. "We are taking sperm from successful males and trying to emulate survival of the fittest," says Bartels.
So far, six lions from Pilanesberg National Park have received vasectomies. Of these, two lions became fertile again when their tubes rejoinedprompting a recent revision of the surgical technique. Four females were inseminated late last year but no pregnancies resulted. The new vasectomy procedure will be tested later this year.
David Wildt, who heads reproductive sciences at the Smithsonian Institution's National Zoological Park in Washington, D.C., isn't optimistic about immediate success.
"Bartels has an interesting concept, but this is not a trivial experiment," he said. "It took our lab 15 years of research into cheetah reproductive biology for us to develop a routine artificial insemination procedure for this cat."
Reproducing lions through artificial insemination, he added, will require much basic research because so little is know about lion ovulation.
Not everyone accepts the insemination approach.
Craig Packer, a veteran lion researcher at the University of Minnesota who has worked with Slotow, said: "The easiest way to introduce genetic diversity is to move animals about and let them do the rest. Artificial insemination is incredibly labor-intensive, expensive, and subjects the lions to a lot of handling."
Even if AI works there is only one litter, and there is no guarantee that the cubs will survive.
There is no doubt that for very small lion populations genetic management is required, said Packer, but it is probably easier to increase genetic diversity by strategically introducing adult females and whole prides into these areas and leaving the matchmaking up to them.
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