Warmblood T
By Amber Heintzberger New Sperm Extender Extends Shelf Life
wo scientists at the University of Newcastle in Australia, Dr. Zamira Gibb and Dr. Aleona Swegen, have devel- oped a nutrient-rich liquid that enables collected horse
semen to live for two weeks outside the body without the need to be frozen. According to a press release from the university, the cur-
rent process for chilling or cryopreserving sperm can cause many viable cells to die off and surviving cells live for just a few hours once warmed up again. “In comparison to cryopre- served sperm, fertility rates could easily be doubled using this new method and the ability to use a more relaxed insemina- tion regimen will potentially save breeders several thousand dollars per pregnancy,” reports Dr. Gibb. Following eight years of research, the first foal bred using
sperm stored in this medium was born on Christmas 2018 in Tamworth, Australia. The foal, a Welsh Mountain Pony/ Thoroughbred cross named Tinsel, lives at Tamworth Equine Veterinary Centre where she is closely observed by equine re- productive specialist and University of Newcastle collaborator Dr. Jen Clulow. The pony shows good signs of health. The global nature of modern horse breeding prompted the initial funding for the project, which received an Austra- lian Research Council Linkage Grant after industry partners at Harness Racing Australia approached the team for alternate methods to access genetics from around the world. Currently, the only commercially available options are to import cryopre- served sperm or to import a stallion on a seasonal basis, which requires international flights and quarantine and is stressful on breeding stallions. “As fertility of cryopreserved sperm is quite low and the
insemination process very labor intensive, the industry wanted a semen extender that could maintain sperm quality for a suf- ficient amount of time for it to be transported from America or Europe for use in a cost-effective insemination regime,” reports Dr. Swegen.
One clear advantage of frozen semen is its “shelf life.” Ac-
cording to Select Breeder Services, the world’s largest provider of frozen semen services, there is no expiration date on frozen semen. As long as the semen is properly maintained at the cor- rect temperature in a liquid nitrogen storage tank, the working life of frozen semen is believed to be nearly unlimited. “In one of the few published trials in which the fertility of fresh, cooled and frozen semen was evaluated from the same
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stallions, the conception rate per cycle of cooled semen (65%) was less than fresh (76%) and the fertility of frozen semen (56%) was slightly less than cooled semen. In general most studies compare populations of mares bred by either cooled or frozen semen,” the Select Breeders website states. The Newcastle University researchers claim the newly de-
veloped liquid supports the sperm with molecules that help protect the cells and enable them to exist in their natural state for longer. The new medium is also completely synthetic, which they say eliminates the biosecurity threat for interna- tional importation and prevents samples from being held up at the border longer than necessary. “This extender has the potential to be widely adopted by
breeders worldwide, not just for importation reasons, but also to reduce the need to collect semen from stallions so fre- quently, which is a real welfare advantage,” says Dr. Gibb. There is already a variety of effective sperm extenders on
the market, at varying price points. For now, American breed- ers remain skeptical of this new extender product as they await more information. Edgar Schutte of Eurequine in Yuba City, California provides
fresh and frozen semen from a variety of stallions to breeders in the U.S. and Canada. “It sounds interesting, and I think it’s useful to have one more tool in your toolbox,” he says. “Some stallions do well with certain extenders and or antibiotics and some do not; they’re all different. No one thing is good for everybody, but it could increase the possibilities for working with semen and getting pregnancies, so that’s great. I have a lot of questions, like maybe it’s cost prohibitive. Does it still need to be cooled? How does it affect your mare? They had success in a lab, but how does it work in the real world? These are the questions that need to be answered.” Natalie DiBerardinis, managing director of Hilltop Farm,
Inc. in Colora, Maryland which offers breeding services to a number of leading sport horse stallions, thinks it’s still early to determine how useful the semen extender will be. “While this product still seems to be very much in the research and devel- opment phase, it’s an interesting concept. We will be following it to see what develops,” she says. The new sperm extender is currently undergoing indepen-
dent testing by a biotech company in Europe and should be commercially available by September 2020.
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