Two weeks ago, one of the Cincinnati Zoo’s Pallas’ cats, Sophia, gave birth to three kittens – the first produced by artificial insemination (AI). Our research progress at CREW with domestic cats and wild cat species over the past 15 years has given us the opportunity to use assisted reproductive technologies to help manage threatened felid populations. While it is always exciting to produce the first offspring of an exotic species with some new reproductive technique, that accomplishment, in itself, is relatively meaningless if that first birth turns out to be the only birth. At CREW, our primary goal is not “world’s firsts”, it is to develop and apply the appropriate scientific tools to help us to conserve endangered wildlife populations. So we produced the world’s first Pallas’ cats by AI – why does that matter?
Well, first, this AI procedure was attempted with Sophia because she decided that she didn’t really like the male, Buster, who was selected as her mate. Zoos uses studbook data and population management software programs to determine which pairings are the most genetically valuable to the population. These breeding recommendations then are distributed to the zoos but, frequently, these carefully chosen pairs prove to be behaviorally incompatible, as with Buster and Sophia. In this instance, AI gave us another option to make this pairing a genetic success. Although Sophia may not have liked Buster very much, she has turned out to be an amazingly attentive mother in raising his kids.
Second, the cross-species success of this new technique – laparoscopic oviductal AI – is changing our approach to assisted propagation of small wild cats like Pallas’ cats, sand cats and ocelots. Small cats are, by definition, small in size – and that adjective applies to the volume of their ejaculates as well. Sperm numbers in small cats often number in the single millions, not the tens or hundreds of millions that can be collected from tigers or other large cat species. But oviductal AI is helping to level the playing field. By depositing the semen deep into the oviducts close to the site of fertilization, high pregnancy percentages can be obtained using only a few million spermatozoa for AI. Case in point – only five million motile spermatozoa were recovered from Buster – likely too few for a conventional AI procedure but, obviously an ample amount for oviductal AI, based on the outcome.
Last, this AI success paves the way to use frozen-thawed semen for insemination in Pallas’ cats. Our research with Pallas’ cats in Mongolia over the past decade has allowed us to collect, freeze and import semen from ten wild males (who then were released back into the wild). These frozen semen straws represent ten potential founders to the zoo population. If we can produce offspring from these frozen samples, the genetic effect would be the same as bringing those ten wild males into captivity. But, because cryopreservation and thawing damages cat spermatozoa and our sperm numbers are already limited, we needed a way to optimize our use of this valuable resource – enter oviductal AI. This technology gives us the means to create gene flow between isolated populations without transporting living animals and conserve genetic diversity within liquid nitrogen tanks as an alternative to maintaining huge living animal populations in space-crunched zoos. That helps us to ensure the future survival of Pallas’ cats and THAT is why it matters.