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Freezing semen at the ERL
Equine Semen Freezing

The Equine Reproduction Laboratory at Colorado State University provides a commercial equine semen freezing and storage service. The objective of this service is to provide horse owners and veterinarians with the latest research and technology available for preserving and storing equine semen. This announcement provides a brief overview of the equine semen service provided by the Equine Reproduction Laboratory. For more complete details and a fee schedule, please contact the Equine Reproduction Laboratory at (970) 491-8626 (tel) or (970) 491-7005 (fax), or e-mail

Semen collection, evaluation, preservation (freezing) and long-term storage of frozen semen is performed at the Equine Reproduction Laboratory. During the initial visit, a stallion undergoes a complete breeding soundness evaluation in order to detect abnormalities that may interfere with fertility. The stallion's semen is frozen using different semen-freezing techniques in order to determine the optimal method of freezing semen for each individual stallion. Aliquots of the semen frozen during the test freeze are thawed and evaluated for their response to the freezing procedure. Currently, semen frozen at the Equine Reproduction Laboratory is packaged in 0.5-ml straws, with 8 straws (800 million sperm cells) representing one insemination dose. Although there is tremendous variability between stallions, a typical ejaculate from a stallion will provide approximately 8 insemination doses (approximately 64 straws).

Once the optimal freezing protocol is identified, subsequent ejaculates from the stallion are frozen using the optimal procedure. Stallions may be housed at the Equine Reproduction Laboratory until enough ejaculates are collected to provide the amount of frozen semen requested by the stallion owner. Once the semen is frozen, it can be stored at the Equine Reproduction Laboratory indefinitely (see cost structures listed below) or it can be transported to another appropriate storage facility. Unless otherwise directed, all semen that is frozen is stored at the Equine Reproduction Laboratory.

Information and Contr​act​
Frozen Semen Storage Contract

Each country has its own regulations and requirements for importing frozen stallion semen. These can be accessed at: or contact Paula at (970) 491-8626.