Breeding the Focus at Alltech's Equine News and Brews Series' First Event

Alltech, which bills itself as having "natural solutions to animal nutrition," is sponsoring a series of roundtable discussion forums with speakers addressing cutting-edge issues from reproduction to traceability in the sport horse to the aging horse.

The first presentation, held Feb. 26 in Lexington, Ky., featured prominent equine reproduction scientist Ed Squires, MS, PhD, an honorary Diplomate in the American College of Theriogenology, director of advancement and industry relations at the University of Kentucky's Maxwell H. Gluck Equine Research Center, and executive director of the Gluck Equine Research Foundation.

Squires spoke on Emerging Reproductive Technologies. He said the acceptance of techonology depends on the success of the technology, the attitude of the breeder and veterinarian, and the cost-to-benefit ratio.

He said evaluation of sperm has been advancing with the introduction of new machinery that makes looking at a variety of sperm traits possible at a very rapid rate. Those traits might include sperm motility, morphology, total sperm numbers, and ratio of live to dead sperm. It also might include testing for the integrity of the membrane and the acrosome reaction and of the DNA integrity, mitochondrial function, and the ability of the sperm to impregnate the oocyte. New technology allows this type of testing on extended or frozen semen.

One of the goals in equine reproduction has been to achieve the same pregnancy rates per cycle with frozen as with fresh or cooled semen. "Once the frozen fertility rates are the same percentage as cooled, there will be no more cooled," said Squires. He noted that cattle breeders have evolved away from cooled semen and only use frozen semen now,

He also stated that horse breeders need to take into consideration the cost of the semen versus the cost of the veterinarian's time. Using a timed insemination protocol means you breed a mare twice in one cycle, which costs less in terms of veterinary time, and the percentage of pregnancy rates increases dramatically.

Squires discussed the pros and cons of various low-dose artificial insemination (AI) methods. This is usually done when semen is of limited supply, is of low quality, on mares with uterine fluid, and mares with post-insemination endometritis. This procedure can be done surgically or via trans-rectal-guided insemination methods.

Sex selection of offspring is done regularly in cattle semen. The machinery is expensive, and equine semen that has been sex-sorted doesn't store as well as cattle semen.

However, intracytoplasmic sperm injection (ICSI) can be used to inject a single sperm into an egg. Squires says this technique is important when you have limited numbers of sperm (such as from a subfertile or dead stallion).

Of Mares and Embryos

On the mare side, the technologies for handling embryos has improved in recent decades. It was 1979 when the first embryo transfer was done successfully in horses, and by the late 1980s countries were transporting embryos. Now there is success with freezing embryos for implantation at a later date.

Using superovulation to collect multiple embryos at one time has helped with the success of embryo transfer technologies, noted Squires.

The topic of cloing was brought up as it is in the news with the American Quarter Horse Association's recent discussion on whether to allow registration of clones. The first equids cloned were racing mules in 2003 in the United States, followed by the first horse clone born later that year in Italy.

What's Next?

In answer to his own question of "What will happen in the next decade?" Squires said the horse industry will determine which technologies are beneficial and should be incorporated. He mentioned that the great Thoroughbred sire Storm Cat got no Thoroughbred mares in foal last year due to fertility problems of his advancing age, and this year he's being bred via ICSI to Quarter Horse mares.

Squires said there is a lesson to be learned here for every breeder: "They should have frozen semen when the stallion was still young and healthy and the sperm (more) viable."

He then opened the floor to questions.

One attendee asked whether one can feed stallions to affect their sperm and fertility. Squires said sperm quality problems can increase when artificial insemination with cooled or frozen semen is involved. The problem stems in part from the fatty acids found in equine sperm. Bull sperm contains high amounts of omega-3 fatty acids that enable them to withstand the rigors involved in freezing. Horses, on the other hand, have sperm that is high in omega-6 fatty acids, which hinders sperm ability to be cooled and frozen, and the sperm is low in omega-3 fatty acids. The most important omega-3 fatty acid is docosahexaenoic acid (DHA). An omega-6 fatty acid found in semen is docosapentaenoic acid (DPA).

Squires said in semen, the fatty acid profile of stallions is similar to that of boars (male hogs). Studies in boars have shown that a high DHA to DPA ratio in semen results in enhanced fertility, whereas higher levels of DPA relative to DHA result in reduced fertility.

He said fresh grass is high in DHA, but unfortunately, a lot of stallions are fed hay and grain.

"Men that have reduced fertility have also been shown to have lower levels of DHA in seminal plasma," Squires noted. "The ratio of phospholipids (fats containing phosphorous) to cholesterol in the sperm, and the ratio of unsaturated to saturated fatty acids, determines the ability of sperm to handle the rigors of cooling and freezing. Those species that have high cholesterol to phospholipid ratio have sperm that are very resistant to cold shock and thawing.

"Humans, rabbits, and roosters produce sperm that are very resistant to cold shock and their sperm freezes very well," he continued. "Sperm from boars and stallions have very low tolerance to cold shock, and, in general, their sperm freezes poorly. Sperm of bulls have high levels of DHA in the cell, where those of stallions have a high level of DPA. Increasing the ration of DHA to DPA in semen has been shown to increase fertilizing capacity and semen quality. Conversely, reducing the ratio of DHA to DPA was accompanied by a reduction in fertilizing capacity."

He said researchers found that adding omega-3 fatty acids to a stallion's diet resulted in a more fluid condition of the sperm membrane, which, in turn, allowed sperm to handle the stress of cooling and freezing with potentially less damage.

Nutrigenomics

An Alltech representative earlier in the program discussed nutrigenomics, which is the study of how nutrition affects gene expression.

Alltech can use a gene chip that contains 40,000 pieces of genetic information to see how various nutrients affect specific genetic expressions. For example, when there was a vitamin E shortage last year for animal feeds, Alltech used this technology to look at the antioxidant properties of other nutrients, such as selenium in poultry diets.

Alltech has created a dedicated Centre for Animal Nutrigenomics and Applied Animal Nutrition at its corporate headquarters in Kentucky. The facility is the first of its kind in the world as it is dedicated to the study of the effect of nutrition on gene expression.

The next Alltech Equine News and Brews Series forum will be held March 26 on Future of Equine health and Wellness, followed on April 16 with The Sport Horse. Reservations are required to attend the forums, and more information can be received by contacting equinenewsandbrews@alltech.com.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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