E d i t o r i a l BREEDS A N D BREEDING

Horse breeding has taken some dramatic steps in the past few years that have set the stage for a new era. Several inovative techniques have been developed which, if utilized by horse breeders, could revolutionize breeding and our breeds.

E m b r y o t ransfer is no longer an exper imenta l procedure. Last year at the Annual Colorado State University Equine Embryo Transfer Short Course, Dr. E. L. Squires summed up the progress they have made in the past five years: "Initially, our efforts were to develop a technique of non-surgica l e m b r y o recovery. This procedure has now been perfected and well over 500 embryos have been collected. Embryo recovery appears to be affected by age of the embryo, seminal treatments, and type of mare but not the technician as long as the technicians are skilled in rectal palpation. Once the embryo is obtained a decision must be made as to the method of transfer...

"The non-surgical method has been modified such that the insemination rod is positioned inside a uterine culture instrument. This protects the rod during passage through the vagina and cervix and insures the deposition of the embryo in the body of the mare's uterus. The surgical method of equine embryo transfer has also been changed dramatically. Initially, the surgical method involved general anesthesia and a mid-ventral incision... During 1982, we developed a new method of surgical ly implanting embryos.., surgery is performed without general anesthesia and with the mare under local anesthesia standing in a breeeding stock."

Dr. Squires suggested that in the future we would have an improved technique for superovulation of the mare. This would provide two or three embryos from a donor mare each estrus. Many breeding farms have developed usable techniques for freezing stallion semen. Foals have been born from previously frozen equine embryos.

Current technology allows the sorting of equine embryos by sex. Accuracy of about 66% is obtainable. Research at CSU may lead to a more reliable means of sexing embryos. Dr. Squires says, "It will probably be a few years before we know if this approach is promising for routine sexing." in relating other current research at The Animal Research Laboratory, Squires says, "There are some indications that it may be possible to detect pregnancy with a blood test as early as a few hours following fertilization. If this can be developed into a practical method, one might simply give prostaglandin five or six days after unsuccessful insemination, and rebreed, thus losing less time. Possibly such tests could be extended so that even the sex of the embryo is indicated 24

by the pregnancy test." Dr. Squires is looking ahead at other futuristic

breeding techniques such as in vitro fertilization and the production of multiple identical twins. He says, "It is possible to manufacture identical twins, triplets, or rarely, quadruplets by dividing embryos into 2, 3 or 4 parts at appropriate stages of development. Not only would more horeses be produced per embryo with these methods, those from each embryo would be genetically identical."

As exciting as these developments are, our current political structure in the horse breeds severely dampens the prospects that these techniques will ever be used to a large extent in the improvement of the breeds. Under the guise of concern for honest and accurate parentage verification, the established registries take a skeptical view of these modern developments.

The reluctance of registries to allow use of new technology in horse breeding may not, however, prevent the advance that many would like to see. Already new registries are forming, geared specifically to the use of every technological advance available. The American Sport Horse Registry is only the first. It could happen with reining horses or cutting horses, and eventually it will even come with racing Thoroughbreds when the pressure builds to a sufficient level.

In the past, it has taken centuries to develop a legitimate breed of horse. New techniques hold the promise that breeding progress can be so rapid that new breeds can be developed in a decade or two. Some new registries may utilize the best horses in a particular breed and make rapid improvement so that in a short time their horses are out-performing those in the original breed. Probably before this happens, the current registries will see the writing on the wall and will allow modern breeding techniques.

All of this will bring great changes in the field of theriogenology. The term "reproductive efficiency" takes on new meaning in light of this new technology and equine specialists need to be aware of what is occurring. We would like to encourage papers on original research and of review regarding new theriogenology techniques.

On the other hand, the d a y - t o - d a y work of theriogenology continues, with diagnosing and treating uterine infections, regulating erratic estrous cycles and the like. Understanding stallion breeding irregularities and development of techniques to correct them are everyday problems to those whose biggest concern today is next year's foal crop. We encourage papers regarding these areas of theriogenology.WEJ

EQUINE VETERINARY SCIENCE