Equine Embryo Transfers

Techniques Of Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 08:02:06 +0000

In the early days of embryo transfer, all collections and transfers were performed surgically. The cost, risk to donor animals, and aftercare have been greatly reduced through the current techniques of non-surgical embryo collection and transfer. The mare is restrained for non-surgical embryo transfer. Her tail is wrapped and held out of the way, while her rectum is emptied of feces. The vulva and perineum is cleansed with a mild soap and a sterile, large bore embryo collection catheter is passed through the vagina, the cervix and into the uterus. The inflatable cuff of the catheter is filled to ensure a snug seal against the cervix. One end of a sterile tubing set is attached to the catheter, and the other connected to a container of warmed sterile solution containing electrolytes, antibiotics and serum. A volume of about 1 liter of fluid is allowed to flow by gravity into the uterus. Through gentle massage of the uterus, embryos present within the uterus become suspended in the flush fluid which is then drained out of the uterus and passed into a fine filter dish which retains the embryo or embryos and a small volume of flush fluid. (more…)

Production Of Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 08:01:30 +0000

The mare’s reproductive or estrous cycle has a conventional length of approximately 21 days through the breeding season. Throughout her cyclic activity, fluid-filled follicles develop on the mare’s ovaries. Towards the end of the ‘heat’ period or estrus during which time the mare is receptive to a stallion, a follicle or occasionally two follicles, grow, mature and release an egg or ovum. The ovum is enthused into the uterine tube where it can be fertilized by a sperm made available by natural or artificial breeding. The fertilized egg or zygote undergoes cell division to become an embryo that is then propelled along the uterine tube towards the uterus. In six days after ovulation the embryo is comprised of a mass of cells and is less than 0.2 mm in diameter when it enters the uterus. The mare is unique in that usually only viable embryos are transported into the uterus. About 25 days after ovulation an embryo that continues to develop moves freely in the uterus before attaching to the uterine lining. (more…)

Preservation And Cost Of Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 08:00:54 +0000

Temporary storage of equine embryos necessitates cautious regulation of temperatures and holding in a special solution. Continuing storage, commonly anything in excess of a day requires that embryos be frozen or cryo-preserved under proscribed programs and stored in liquid nitrogen. When frozen, embryos remain stable for many years. This implies that embryos may be collected at times when a pregnancy is not normally desired and frozen for transfer at a later date. This can add considerable flexibility to numerous equine embryo transfers programs, and permits the international or inter-continental movement of equine genetics. Nonetheless, in addition to the concerns that apply to the transfer of fresh embryos, frozen embryos must be handled with care and liquefied under suitable conditions prior to their transfer into recipients, and at the appropriate stage of their cycle. It is atypical for pregnancy rates with frozen embryos to be as high as those obtained with fresh transferred embryos. (more…)

Period Of Collection Of Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 08:00:12 +0000

An extremely fascinating aspect to equine embryo transfer is that donor mares may continue in competition or training and still produce a foal without becoming pregnant themselves. Embryo collections intended for mares that foal late in a year are being performed by transferring the embryo to a recipient or it is being frozen. The donor mare bred earlier the following year. The international movement of equine genetics through the import and export of frozen embryos have considerably lower the cost of transporting embryos as compared to that of the live mares. Then the international concerns regarding disease control are being tackled through embryo transfer talks. Embryo donor mares may be raised through artificial insemination or by natural cover. In any case, it is essential that the time of ovulation is known within 12 hours. Embryo recovery is usually attempted on day 7, where day 0 is the day of ovulation. A fertilized embryo can be recovered on day 7 in 60-70% of attempts through natural breeding and with assumption of the normal fertility of the stallion and mare. If artificial inseminations with older infertile mares or frozen semen are part of embryo program, then the rate of embryo recovery is low. (more…)

Limitations Of Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 07:59:11 +0000

The utilization of embryo transfer in the horse has progressed steadily over the past couple of decades. Nevertheless, numerous unique biological features as well as technical problems have restricted its prevalent use in the horse as compared with the other industry. Reasons that affect embryo recovery include the quality of sire’s semen, age of the donor, day of recovery, and the number of ovulations. Usually, embryo recoveries are performed 7 or 8 days after ovulation if not the embryos are to be frozen, in which case recovery is performed 6 days after ovulation. The majority of the embryos are recovered from single-ovulating mares. For the reason that there is no commercially available hormonal preparation for inducing multiple ovulations in the horse, equine pituitary extract has been utilized to boost the number of ovulations in treated mares. However, FSH of ovine or porcine origin is relatively unproductive in inducing multiple ovulations in the mare. Factors made known to affect pregnancy rates after embryo transfer include embryo quality, synchrony of the donor and recipient, method of transfer, and management of the recipient. (more…)

Equine Embryo Transfer

equineembryotransfers — Mon, 14 May 2007 07:52:23 +0000

Equine Embryo Transfer (EET) is a recognized reproductive technology that relates to the collection of an embryo (or embryos) from a donor female. It is a process that is becoming more and more popular in the equine world for obtaining foals. This technique involves recovering embryos from bred (donor) mares and placing them in a recipient mare who, in turn, carries the foal, or the embryo is transferred into a recipient or surrogate mother where a pregnancy can be established and maintained, resulting in the birth of live offspring. Embryo transfer has been used to a great commercial benefit in many species and has applications in equine procreation. There are several reasons for the use of this procedure. First, multiple foals can be produced from one mare (possibly genetically superior) in a breeding season. Second, it can be used to bring into being the foals from mares that cannot take time off from racing or showing. Third, embryo transfer can also be used to produce foals from sub-fertile mares that are incapable to successfully carry a foal to term. Fourth, young fillies that can produce feasible embryos but are not yet able to carry them may be used as donor mares. Fifth, older mares no longer competent of carrying a foal also make good candidates for embryo transfer. Last but not the least, the embryo transfer also cuts down on breeding injuries and the spread of venereal diseases to the horses. Nonetheless, this is not an accepted method of breeding for all breeds of horses. Better verify with the particular breed registry rather than choosing embryo transfer as a breeding method. (more…)