While artificial insemination (AI) might not be every breeders' first choice of breeding method, it does offer flexibility in accommodating stallion and mare schedules, as well as access to the worldwide market. Further, researchers are continually improving the methods by which semen is processed to improve the quality buyers receive.

Jane Morrell, FRCVS, of the Swedish University of Agricultural Sciences recently lead a research team in testing a scaled-up method of semen processing designed to improve AI efficacy.

"Our previous studies have shown that stallion sperm quality could be improved using single layer centrifugation (SLC) through the colloid Androcoll-E," explained Morrell.

"In the current study with stored semen, we have shown that it is also possible to improve sperm quality in AI doses that have been shipped to other studs, and that one can prolong the 'shelf-life' of the semen doses in this manner if it is not needed for AI on the day that it is received at the stud," she added.

In their study, Morrell et al. processed three cooled semen doses from each of 15 stallions using SLC with Androcoll-E-Large 24 hours after collection and subsequent shipment. Single layer centrifugation with Androcoll-E utilizes a silane-coated silica formulation that optimizes stallion spermatozoa. Androcoll-E-Large (50 ml tubes) enables larger volumes of stallion semen to be processed than Androcoll-E-Small (15 ml tubes).

Results demonstrated that semen processed by SLC with Androcoll-E-Large was improved compared to uncentrifuged samples in terms of mean sperm motility, chromatin integrity, and morphology (sperm structure). In addition, the improvement in sperm quality was maintained an additional 24 hours after processing (i.e., 48 hours after semen collection). These findings indicate processing cooled semen using SLC with Androcoll-E-Large produces sperm quality that is comparable to fresh SLC-processed semen samples.

"Since pregnancy rates are directly linked to sperm quality in AI doses, improving the sperm quality should help to increase pregnancy rates if other factors such as mare fertility, handling techniques, and insemination technique are optimal," noted Morrell.

Extending AI semen doses' shelf-life offers breeders an additional option for improving sperm quality for AI breeding and enables mares to be inseminated close to ovulation.

This study, "Processing stored stallion semen doses by Single Layer Centrifugation," was published in the November 2011 issue of Theriogenology. The abstract is available on Pubmed.

About the Author

Natalie DeFee Mendik, MA

Freelance journalist Natalie DeFee Mendik is a multiple American Horse Publications editorial and graphics awards winner specializing in equestrian media. She holds an MA in English from Colorado State University and an International Federation of Journalists' International press card, and is a member of the International Alliance of Equestrian Journalists. With over three decades of horse experience, Natalie’s main equine interests are dressage and vaulting. Having lived and ridden in England, Switzerland, and various parts of the United States, Natalie currently resides in Colorado with her husband and two girls.

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