Equine Cryopreservation

 

 

Mandy Paul, owner of Breeder’s Choice, was kind enough to answer a few questions about the equine breeding industry and some of its challenges. 

 

Q Do all equines have semen that can be frozen? 
A In many other species, for example cows, pigs, etc., reproductive qualities (like semen quality) is selected when considering mating. However, semen quality is not a “selected” reproductive quality for equines. We look at other factors like speed and color when choosing horses to mate. Horse semen can vary in quality and freezability, but most horse semen can be frozen with good viability once thawed.
Q What is the basic collection process? 
A Most facilities that collect stallion semen have a breeding shed and a breeding phantom. The breeding phantom increases the safety of the collection. It is a large “dummy horse” that the stallion can jump on instead of a live mare. A hot water filled latex liner with lube is used to simulate the mare’s vagina. At the end of the artificial vagina is a bottle to collect the ejaculate. Light and/or temperature variations can severely damage the sperm, so it is handled carefully.
Q What is the preferred freezing process? 
A Most stallion semen is frozen in a milk/egg yolk extender that contains glycerol as the cryprotectant.  It is then placed into .5ml freezing straws and frozen down to -120°C in 8 minutes using a programmable controlled rate freezer.  Once frozen the straws are stored in tanks of liquidnitrogen at -196°C.
Q What are the advantages of using a controlled rate freezer versus just freezing in vapor? 
A A controlled rate freezer offers the advantage of being able to control the rate of cooling to an accuracy of 0.1 °C/min. (active cooling). This enables us to define precise freezing protocols that are consistent and repeatable with every freeze. Freezing over vapor, or passive cooling, offers limited ability to adjust the rate of cooling and does not have the same repeatability.
Q What are the advantages and disadvantages of frozen semen? 
A Most mares are bred around the US via cooled shipped semen that has been collected and cooled down to 5°C, shipped and used within 24-48 hours. You need to keep a close watch on the mare to see if she is going to ovulate and then call the stallion owner to get semen collected, processed, shipped with no delays, and inseminate the mare before she ovulates. That is a lot to get done in 24 hours and you can’t get it overseas that quickly. The beauty of frozen semen is it can be shipped at the beginning of the breeding season and be there waiting for the mare to ovulate. Meanwhile the stallion can race or do shows or whatever else his job is.
Q How is frozen semen transported? 
A Much like other specimens that need to stay frozen it is transported in a liquid nitrogen vapor shipper.
Q How long can semen be stored? 
A Indefinitely.
Q What are the latest reproductive techniques in the industry? 
A Sexing semen before it is used or frozen is a new technology that is gaining momentum. The owner can say this sample will give you a filly or a colt. It is of even greater value to the dairy industry.
Thank you Mandy for sharing your expertise in frozen semen technology.  Visit http://www.breederschoiceonline.com/ for more information.

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