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Stallion Services > Semen Evaluation

After semen has been collected into the AV it is evaluated by QEC veterinarians. The four main factors that determine the quality of semen are volume, concentration, motility, and velocity. Higher concentration semen is more desirable, as number of live sperm will determine how many doses of semen are in each collection. If a stallion has an extremely low sperm concentration, the semen may need further processing such as centrifugation in order to concentrate the sample. Progressive motility is the measure of live, forward-moving sperm in the sample. QEC veterinarians like to see this number at least 60%. Finally, the velocity is a rating of how effectively and quickly the sperm are moving in a direction (not circling).

A combination of the above factors will determine the suitability of each stallion for cool-shipping or freezing. If a stallion has particularly low concentration or motility his semen may not ship or freeze successfully. QEC can perform semen longevity trials where individual samples of semen are mixed with several different extenders (a medium added to semen after collection that contains nutrients for sperm and may contain antibiotics). The semen is packed in a shipper as if it were being sent away, then each sample will be checked at 24 and 48 hours later for percentage of progressively motile sperm. Some extenders may preserve the semen better than others, and the best extender for shipping a particular stallion semen is determined. If the sample remains at least 50% at 24hrs, but more desirably around 70%, progressively motile, there is a good chance the semen will ship and/or freeze well.

Stallions that have not been serving mares routinely will build up excess seminal fluid and dead sperm. These stallions may need up to a week of "cleanout" collections before a good sample of semen is collected.