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Background of Cooled Semen

Results using Cooled Semen

Cooled, transported semen (TS) was first successfully used in a 1983 field trial at Hamilton Farm (South Hamilton, MA). Results of the field trial (50 mares, 3 stallions) indicated that TS can achieve conception rates equal to those on the best farms. Cumulative statistics per cycle showed the following:

  • 1st cycle total percentage of mares in foal = 62%
  • 2nd cycle total percentage of mares in foal = 82%
  • 3rd cycle total percentage of mares in foal = 90%

Since then, breeding farms around the world have been using TS with similar results.

The Cooling Rate is the Key.

Because sperm are highly susceptible to "cold shock," cooling the semen at the proper rate is necessary to prevent irreversible damage to the sperm. The Equitainer was designed to provide a controlled environment that gradually cools the extended semen sample at a rate of -0.05°C/min down to a minimum temperature of approximately 4°C. It then maintains the sample at the proper refrigerated temperature for up to 70 hours (Equitainer I) while also preventing freezing of the sample. It is critical that the sample does not freeze during shipment. While freezing is an alternative for long distance breeding, the process involves specialized equipment and a strict protocol.

Use of a Semen Extender is also Necessary.

Extender, to which antibiotics have been added, provides nutrients to the sperm and prevents growth of bacteria. If extender is not added to the semen sample within 15 minutes, sperm survivability is drastically reduced. In addition to maintaining sperm viability, there is another advantage of using extender. Diluting the ejaculate allows multiple mares may be bred from a single ejaculate (providing the raw ejaculate has a sufficient sperm concentration).

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