An Original Article Written by Lorraine Beaumont, DVM
My first experience with breeding a mare was over 50 yrs. ago when, as a horse crazy teenager, I wanted to breed my grade mare to an Arab stallion. We simply hauled her over to a local stallion, left her for a few days, and brought her home to wait 11 mos. NO consideration of A.I., NO uterine culture or cytology, NO pregnancy check, Not even a written contract. Certainly frozen semen for horses was out of the question then. (Although, it was a well established technique for bulls.)
Breeding with frozen semen is very different from natural/ live cover. There are some obvious advantages: being able to breed to a stallion in another state or country, breeding to a deceased stallion, breeding while the stallion is at a show. But there are also some challenges. It is generally accepted that even a fertile stallion will have a lower conception rate with frozen semen than with live cover or fresh cooled semen.
What can be done to improve the conception rate when using frozen semen.
Most importantly is to utilize the services of an equine veterinarian who has advanced training and experience in equine reproduction (the majority of his/her practice should be equine reproduction) for the initial collection and preservation of the stallion’s semen. An equine reproductive veterinarian will go beyond the commercial extenders that are available and will often work with custom made extenders for an individual stallion whose semen is very fragile.
When it is time to breed your mare be sure that she is under the management of an equine veterinarian for regular palpations and insemination. It is also recommended that the storage of the stallion’s semen be managed by a reproductive veterinarian. There is often quite an investment in the purchase price of the semen. By using a reproductive veterinarian you are protecting this investment and increasing the probability of a live foal in 11 mos.
Before choosing the frozen semen to use there are some questions to ask the stallion owner or manager:
WHAT IS THE POST-THAW MOTILITY?
This should be progressive motility with a forward “going some place” movement. For general guidelines, 65% progressive motility is considered very good, 20 % motility with good concentration and morphology might result in a pregnancy, but 1-5% would require nothing short of a miracle for conception. Don’t accept a descriptive answer such as, “Oh, it is really good.”
WHAT IS THE MORPHOLOGY OF THE SPERM?
Each sperm cell is composed of a head, tail and mid-piece. An abnormality such as a double head, split tails, curled tails are some of the abnormalities that, if present in high numbers, can lower the fertility. These abnormalities often reduce the motility. There should be records of the post-thaw motility and morphology on any stallion semen being used.
HOW MANY MARES HAVE BEEN BRED WITH THE FROZEN SEMEN?
What was the conception rate, the average number of breedings per pregnancy, and how many live foals have been born using this frozen semen? Even if this stallion’s frozen semen has not been used commercially , a test breeding should have been done when the semen was initially collected if the owner had intended to offer the frozen semen publicly.
HOW LONG AGO WAS THE SEMEN COLLECTED AND FROZEN?
If the semen has been properly handled, there should be no significant change in motility? But the technology involved in freezing equine semen was not nearly as advanced 30 yrs. ago as it was ten yrs. ago. There were not as many different extenders available to use with an individual stallion’s semen 30 yrs. ago. And even the best extender for that stallion might not have produced commercial quality frozen semen.
WHAT LABELING INFORMATION IS INCLUDED ON THE STRAW?
The name and breed of the stallion allows for proper identification. The date of collection is important as not all collections are necessarily equal in quality. If you receive some straws that are poor quality you can request straws of a different collection date on the next shipment. Other information pertaining to extender used, name of veterinarian collecting the semen and location of collection might also be included.
WHAT SIZE OF STRAW ARE YOU PURCHASING?
Sometimes a smaller straw (typically 0.5 cm) is produced and sometimes a larger straw (4-5 cm) is filled. Obviously eight small straws are not equal to eight large straws. How many straws are considered a full dose? Depending upon normal concentration, motility, and morphology; eight small straws are often used as one dose (one breeding). One larger straw is usually considered a full dose. On the other hand if the post-thaw motility is down to one percent and there is abnormal morphology of the sperm, 50 straws would hardly be considered an adequate dose for conception.
READ ALL ASPECTS OF THE CONTRACT
This, of course, is true for any contract. Read it before you sign it. Is there a live foal guarantee? How many straws are provided with the breeding fee? What are to be done with any remaining straws if the mare conceives with only one straw? Does the purchaser get to keep them or are they required to ship them back to the stallion owner/manager? If they are to be shipped back, who pays the shipping expenses?
Finally, I would like to suggest that you use an equine reproductive veterinarian for any and all work in breeding your mare with frozen semen. (I know that I have already recommended this, but it is important enough to repeat). The mare needs to be kept in a facility where she can be palpated every four to six hrs. as she approaches ovulation. Timing of insemination is crucial in breeding a mare with frozen semen. And proper handling of semen at the time of insemination is extremely important. You don’t have a few minutes to remove the semen from the liquid nitrogen container, get your equipment in place and artificially inseminate the mare.
Best wishes to anyone who is breeding their Morgan mare this year. Whether live cover, cooled shipped semen, or frozen semen may you get the color and gender that you want in your new foal.
Previously published in the 2016 MHAO Breeders' Cup Futurity Booklet
Photo by Leslie Arnould, SSLLC In Vogue with her 2017 foal Akira Embellished by HVK Bell Flaire