Equine practitioners now have a new, accurate tool for measuring stallion fertility--the NucleoCounter SP-100 fluorescence-based instrument. While it is more expensive than some instruments currently used for counting sperm, it is accurate and easy to use, according to a study presented at the 2008 American Association of Equine Practitioners convention, held Dec. 6-10 in San Diego, Calif.

Measuring a stallion's sperm concentration accurately is important for assessing sperm quality and calculating breeding doses for artificial insemination. The "gold standard" equipment options for counting sperm in stallion semen currently are the hemacytometer (a microscope-based system in which a person counts the sperm) and flow cytometer (an expensive laser-based counting system).

Kathryn Comerford, BS, a graduate student in reproductive biology at Texas A&M University, presented the results of several experiments comparing the NucleoCounter's performance to that of a hemacytometer and a flow cytometer. The NucleoCounter provided acceptable agreement with both the flow cytometer and the hemacytometer, and it had excellent within-sample repeatability of 3.17% (this refers to the precision of the instrument, for example, how close each sample measurement is to the others; in general, acceptable repeatability is considered to be anything below 10%). In addition, she noted that it is "far less laborious to use" than the hemacytometer and flow cytometer, and it can accurately measure sperm concentrations in raw ejaculate that's contaminated with urine and red/white blood cells.

"This is the only automated instrument currently available that can measure sperm in opaque extender," Comerford noted. "It has application for sending/receiving extended semen, semen freezing, and low-dose artificial insemination. However, it's expensive (about $15,000) compared to hemacytometer and photometric systems (with hemacytometers ranging from $200-300, and photometric systems, $2,000-3,000). Each operation must decide for themselves if the cost of the instrument is less than that of open mares resulting from inaccurate sperm concentration measurements."

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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