Sport horse stallions with heavy competition schedules. Mare owners requiring semen at time of ovulation. "Problem" stallions with poor-quality sperm. These are just some of the problems breeders commonly face. Luckily for managers of these horses, there’s a simple artificial insemination technique that could help address these problems and others: single layer centrifugation (SLC). A recent review on the topic identified some of the procedure’s benefits.

This semen processing technique, first introduced in 1997, uses Androcoll-E, a colloid specific to horses, according to Jane Morrell, FRCVS, of the Swedish University of Agricultural Sciences, who recently completed a review on the topic. While an artificial insemination (AI) trial involving large numbers of mares necessary for statistical purposes is under way, Morrell notes in her review that some of SLC’s benefits to owners and breeders have already been identified. They include:

• Extended "shelf-life" of semen, either by processing fresh semen for AI doses or by extracting the best quality sperm from stored doses. Progressive motility in SLC-selected spermatozoa can be maintained at least 96 hours.
• Improved quality of AI semen doses. This is particularly beneficial in stallions with poor-quality sperm, as scientists have extracted normal spermatozoa from subfertile semen using SLC.
• Provides alternative for sperm that doesn’t tolerate cooling.
• Removes dead and dying sperm prior to cryopreservation to improve overall semen quality.
• Selects quality spermatozoa after thawing semen.
• Can, but doesn’t always, remove viruses and bacteria from semen.
• Enables owners and veterinarians to processing whole ejaculates.

"Breeders benefit from being able to improve sperm quality in semen doses by selecting sperm with good motility, normal morphology, good membrane integrity, and good chromatin integrity," Morrell relayed. "These selected sperm samples have a longer ‘shelf-life’ than ordinary sperm doses–they can be stored in the fridge for 96 hours before AI and still produce pregnancies–and, thus, the breeder has more chance of supplying all the orders for semen doses when they are required. Being able to prepare chilled sperm doses from stallions whose ejaculate does not normally survive cooling is a real plus. Any help with improving sperm survival during freezing is also good news."

Morrell notes SLC processing is a simple procedure that can be performed with a centrifuge at the breeder’s home facility, or semen can be shipped to another location for processing