Successful breeding with cooled or frozen semen depends on a good working relationship between the breeder, the mare owner, and the veterinarians. Stallion and mare management, semen handling, and correct timing for insemination are our priorities. The following recommendations should help maximize fertility.

 

Stallion Breeder's Role

The best results will be achieved when the collections and processing is performed at 37 degrees Celsius. The semen is mixed with extender, sealed, and placed in an "Equitainer" shipping container which slowly cools the semen to 5 degrees Celsius to avoid damage to the sperm cell membrane. The container holds the temperature for 70 hours which allows a little more latitude for breeding; but since sperm starts to break down after 24 hours, immediate insemination is preferred for ideal consequences.

Our customers are assured of receiving a quality-controlled product. The semen has been analyzed and tested and is free from infectious and contagious disease. Our sperm count, motility, collection and packaging procedures meet or exceed industry standards.

The Process

Cooled

The process begins when the raw semen is poured into a sterile cup. The volume is recorded and the sperm analyzed to determine the number of viable cells per milliliter of fluid. The semen is mixed with an extender that has previously been tested and found compatible with that particular stallion's chemical makeup.

Extender performs several functions, most notably that of counteracting the effects of the stallion's own seminal fluid. The seminal fluid that carries the sperm cells during ejaculation can kill them unless diluted by extender. If the sperm cell count is high enough, dilution allows the laboratory to "split" an ejaculate into several portions for shipment. Extender also provides nutrients to the sperm cells, ensuring they remain motile for as long as possible during storage and transport. Antibiotics can be added to the extender to destroy the bacteria present in the semen from live breeding.

Once the semen has been processed at the correct temperature, it is quickly packaged and placed in a shipping container that is designed to provide the optimum cooling curve for semen. Over the course of the next 10 hours, the semen is cooled from 37 degrees Centigrade to 5 degrees Centigrade (42 degrees Fahrenheit). Cooling at any other rate can negatively affect the viability of the semen.

Our Stallion Service Contract includes two (2) doses of cooled semen. The national average for the number of doses to successfully inseminate a mare is 1.8, so we have provided for more than adequate coverage.

Additional shipments of semen can be provided thereafter, if necessary, for a predetermined amount as listed on your breeding contract, plus shipping.

The stallion has been tested for CEM and EVA prior to collection and his semen has been rigorously tested and analyzed to ensure that you receive a quality product that is free from disease and has a high motile sperm count, even after it has been cooled.

 

Frozen

The processing of frozen semen begins the same way. The stallion is collected and semen analyzed to determine the sperm concentration per milliliter, motility and progressive motility. At this point it is mixed with an appropriate extender, centrifuged to remove seminal plasma and to concentrate the spermatozoa, re suspended in a freezing extender containing a cryoprotectant, cooled to -120°C(- 184°F) and stored in liquid nitrogen at -196°C(-320°F).

The thawing process is typically that 0.5 ml straws of stallion spermatozoa are warmed by immersion in 37°C(98.6°F) water for 30 seconds or by immersion in 75°C(167°F) for exactly 7 seconds immediately followed by immersion in 37°C(98.6°F) water.

Thawing directions are included with all shipments of frozen semen.

As part of the testing process, pre-freeze and post-thaw motility counts are determined to ensure an adequate concentration of viable sperm.

 

Broodmare Management

The stallion breeder can package and send top quality semen, but the success of the endeavor relies on the expertise of the mare owner's veterinarian, and ultimately on the mare. The mare owner who does not have his or her animal thoroughly checked for reproductive disorders prior to breeding, or who does not expend the effort to chart the mare's heat cycles, may be unwittingly sabotaging the breeding process. If the veterinarian misses the ovulation estimate, or the mare's biological clock misses a tick and she doesn't co-operate, the mare may not get in foal. Clinical research involving 55 mares showed that the 1st cycle conception rate was 65%, but that two breedings produced a 91% conception rate (which is why we include 2 doses of semen in our contract).

A qualified veterinarian should be consulted to assess the mare's fertility status. Particular attention should be paid to the mare's reproductive history. If the mare is barren and has had any history of uterine infection or dystocia, a thorough breeding soundness exam -- including uterine culture and biopsy -- should be performed. Only reproductively sound mares should be considered in a breeding program utilizing transported cooled or frozen semen.

If you plan to breed the mare earlier than March, April or May, when heat cycles occur naturally, we recommend artificial lighting for 14 to 16 hours a day (a 200 watt bulb or equivalent) to simulate summer breeding conditions. Artificial lighting has also been proven successful with pregnant mares and appears to increase the chances of foal-heat conception.

Veterinarians who must rely on observation of an unteased mare are at a disadvantage in determining the optimum time to breed. Tease your mare frequently until she shows signs of heat and then ask your veterinarian to ultrasound the mare every other day and record the findings to accurately track the progression of the cycle. The ultrasound machine is a wonderful tool that takes the guess-work out of breeding. The veterinarian can measure the size of the follicle(s) and determine over the next 5 to 7 days whether the mare is having a "normal" heat cycle where follicles will steadily grow a little more each day. A follicle that "sticks" on one size for several days can be an indication that the mare is still partially in winter anestrus and is not having optimum cycles for insemination. Keep good records of each ultrasound or palpation to see if the mare's follicles are growing and developing daily to determine whether she is having a "normal" cycle.

Mares can have completely different cycles from year to year. Don't assume that she will breed easily this year just because she has in the past. Reproductive systems change with age. Since the stallion breeder's role is limited to providing a timely shipment of viable equine sperm, the mare owner and his or her veterinarian must assume the major responsibility of preparing the mare for breeding.

 

Timing of Insemination

Insemination is allowed up to 72 hours following collection, but the quality of the sperm cells deteriorate rapidly after 24 hours. Most reproductive specialists agree that unless the individual stallion is known for exceptional sperm production, it would be inadvisable to inseminate after 48 hours. Sperm have a limited "shelf-life" which is why we request that it is used immediately.

In order to breed during the most optimal period of time, the mare must be teased daily until she comes into season. The veterinarian should then check the mare daily until a 35mm follicle is palpated. It is then recommended that the veterinarian ultrasound and/or palpate the mare frequently until the follicle becomes very soft and fluctuant. Some breeders check 2 or 3 times a day. At that time many breeding specialists recommend using human chorionic gonadotropin (HCG) at a rate of 3,000 IM to induce ovulation.

Mares with mature follicles generally ovulate within 24 to 36 hours of HCG administration. The veterinarian should continue to palpate frequently after HCG and inseminate just prior to ovulation. Again, at this point, many top breeders ultrasound and/or palpate 2 or 3 times a day for optimum results.

The vet will normally ultrasound or palpate the mare and then inseminate.

The mare must be ultra-sounded at 14 to 16 days following breeding, and again at 21 days to rule out twinning and false pregnancy, as some mares will continue to show heat even when they are pregnant. Pregnancy should then be reconfirmed via palpation or ultrasound at 30 to 45 days.