When the American Paint Horse Association holds its 2000 convention and membership meeting in Seattle during the first week in October, it will have two significant breeding ...When the American Paint Horse Association holds its 2000 convention and membership meeting in Seattle during the first week in October, it will have two significant breeding ...
When the American Paint Horse Association holds its 2000 convention and membership meeting in Seattle during the first week in October, it will have two significant breeding issues to consider: the use of frozen semen and multiple embryo transfers. Currently, both procedures are not allowed in the Paint Horse world, but recent advances in the science of equine reproduction has given the association an opportunity to follow the rising medical technology curve. Should the two be authorized, they could have a substantial impact on the registry.
The APHA seems to be following the lead set by the American Quarter Horse Association, which voted this spring to allow the use of frozen semen. The APHA’s frozen semen guidelines mirror the AQHA except in its use after the stallion’s death. In the case of the AQHA, it mandated that the genetic material has to be used before December 31 following the date of the stallion’s death. That is, if a stallion dies on March 15, 2001, it’s legal to use his frozen semen until Dec. 31, 2001. The APHA is proposing that frozen semen be used for 24 months after the stallion’s death, giving Paint owners as much as a year to use the semen over what a Quarter Horse stallion owner has.
Both associations allow the use of cooled semen, a procedure that keeps semen viable for usually no more than 48 hours. Frozen semen could be thawed out and used years later. AQHA said that foreign members originally pushed for the rule, which would allow them to breed their mares to American-based stallions.
According to said AQHA’s Studbook and Registration Committee Chairman Dr. Glen Blodgett, the staff veterinarian of the 6666 Ranch in Guthrie, Texas, the decision was made for practical reasons.
"The international people really wanted frozen semen because the health regulations and import requirements on cooled transported semen virtually prohibit them from the use of cooled transported semen," he said. "The advantages that I see – domestically in the United States – is for people who live in remote areas and have problems getting delivery of cooled transported semen in a timely manner. Also, there are breeding days for horses that have a lot of breeding pressure, that mare owners or veterinarians call in and request cooled transported semen, the stallions are overbooked for that day and they miss the mare for that whole cycle. So, there’s a lot of expense on the part of the mare owner having to recycle the mare and breeding her again on a subsequent cycle.
"Also, if the stallion becomes sick or injured, it will possibly prevent the disruption of breeding."
According to Dr. Edward Squires, a physiology professor with Colorado State University, frozen semen could allow for an additional 75 to 100 extra breedings per year, nearly doubling a stallion’s breeding rate.
Most of the top cutting stallion owners have been freezing semen for years. They’re not necessarily breeding mares with frozen semen, but are instead saving the DNA material for the time when their stallion becomes sterile or dies.
According to the AQHA, breeders will be able to use frozen semen beginning January 2001. If the APHA proposal passes, it will become effective the first of the year as well.
As to the issue of multiple embryo transfers, the APHA is considering allowing it only if the foals are by different stallions. The AQHA voted down the same proposal at its convention in March. Technology allows an embryo to be flushed from an impregnated mare and implanted in a recipient mare, who then gives birth to the foal 11 months later. Several embryos could be flushed in a season, allowing a mare to compete and produce offspring at the same time. It also doubles her foal production, something desired if she’s an especially talented mare.
According to Whit Byers of Select Breeders Service of Aubrey, Texas, freezing and thawing semen is fairly easy. Winding up with viable semen after thawing is the dicey part. It all depends on how well a stallion’s semen can withstand the procedure and the freezing method used.
"The minimum industry standards for post-thaw progressive motility is 30 percent," Byers said. "Less than 30 percent and it’s not considered commercial-quality semen. It’s all stallion-dependent. I had a horse last week that started off at 70 percent progressive motility before freezing and after freezing he was still 70 percent. But, only 10 percent of stallions may be like that."
Byers defines motility as sperm moving in a relatively straight line at a good speed. The word mobility is sometimes used in place of motility, but the proper word to describe sperm movement is motility.
Byers pointed out that motility doesn’t necessarily indicate fertility, either before or after freezing.
"Motility is the standard everyone uses," he said. "But, a lot of research is being done to determine a better way of determining fertility without actually breeding mares. Occasionally we’ll find a stallion that freezes well – he may have 40 to 45 percent post-thaw motility – but you can’t get a mare pregnant with his frozen semen. We suspect there’s some kind of damage being done during freezing that we can’t evaluate under the microscope."
Extenders are added before freezing to protect cell membranes and minimize crystallization of water within the cells. A carefully managed freeze and thaw curve is employed to further minimize cell death.
Byers said that 90 percent of the semen Select Breeders Service freezes is stored and then sent to mare owners on orders of the stallion owners. The straws are thawed in a warm water bath at 100 degrees F or 37 degrees C. The thawing procedure for a typical straw takes only 20 to 30 seconds.
In anticipation of increased demand from the recent AQHA ruling allowing frozen semen, Select Breeders Service has added technicians to their staff. Byers said that previously only a very small percent of their business has been with Quarter Horse owners, and that was mainly freezing and storage of semen.
When asked why the cattle industry has such a high success rate with freezing, Byers said that industry has had 30 years to select bulls with high freezeability rates. It could be considered a case of forced natural selection. Bulls with high-fertility frozen semen are the ones that impregnate the majority of cows, enhancing the bovine gene pool with their freezing-friendly semen characteristics.