Standards in the cold preservation of bovine semen are now being
successfully transferred to horses.
Claire Card, a professor at the Western College of Veterinary Medicine
at the University of Saskatchewan, has recently completed a report for
the Saskatchewan government about her study of cryopreserved horse
semen.
Research shows that if some techniques and standards for bovine semen
preparation and freezing are met, predictable rates of pregnancy in
horses can be expected.
When sperm collected and stored under the new standards is combined
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with greater understanding of horses’ ovulation timing, producers can
expect pregnancy rates of up to 40 percent per ovulation, said Card.
Cattle producers have relied for years on cryopreserved semen in herd
reproduction programs. They can source bulls from around the world at
low cost, without the problems of moving live animals across borders.
Semen can be collected and saved for use during breeding cycles when
bulls are not available and animal health can be secured by keeping
closed herds.
Horse producers have not enjoyed the same luxury. Only recently has
frozen semen been used with frequency in the equine industry. The
desire for semen from a high quality frozen-sire, as they are known in
horse circles, is shown through the high price of semen on the world
market.
Many of the best studs are competing or showing throughout the spring
and summer breeding season. The use of cryopreserved semen would allow
collection during the quieter winter months.
Chilled or fresh semen has long been used for inseminating mares. But
obtaining, transporting and using this highly perishable commodity is
tricky.
Reliability of frozen semen was uncertain and compounding problems with
technique is the tradition of selling it by the dose rather than by the
breeding.
“It can be very expensive by the dose and have very uncertain results.
If the industry is willing to change and charge by the breeding, and
apply some standards, then I think (artificial insemination) will give
breeders a real opportunity to improve herds,” said Card.
“Bulls have been bred to reproduce. Horses haven’t …. Horses are a
different species that in the wild tend to look after only a few
females with limited competition, unlike cattle,” said Card.
Because equine reproduction systems are not as efficient as those of
cattle, and the sperm are not as consistent or stable, horses require
up to 10 times the amount of sperm per dose.
In bulls, a single ejaculation can provide up to 200 doses, but only
three to five doses are common for stallions.
Card said horse owners should expect the following standard: 50 percent
of equine sperm should be normal in structure at ejaculation; there
should be 30 percent motility after thawing; and 85 percent of the
enzyme caps that top the sperm and make it able to dissolve the outer
wall of the egg should be intact.
“More research needs to be done. But now we have a few standards to
work with,” she said.
