Around 20 years ago, when the first filly of embryo transference was born, it already had the conscience of the impact that this technique could cause in the circle of equine creation.

The most informed creators and owners of mares already started to dream with a possibility to get more than one colt per year of its better mares. The embryos transference comes exactly to try to help the creators to transpose the pot in the creation of high quality horses that is the scarceness of proven matrices. Moved to a second plain in a circle where the sires had always been the main star of each cattle farm, the mares were little by little getting the deserved recognition and today it knows that a horse cattle farm lives without a good sire but not without good matrices.

DEFINITION

The embryos transference, by definition, is an artificial method of reproduction that is used to remove an embryo of the mare’s giver uterus and to take it to the interior of a receiver mare. The receiver will be in charge to take the gestation till the end and will assure the lactation equally.

Basics proceeding realized in the embryos transference are:

• Ovulation Synchronization between givers and receiving;
• Covering or insemination of the giver mare;
• Washing of the giver uterus and harvest of the embryo, normally in 7º or 8° day after the giver ovulation;
• Localization, manipulation and eventual stock of the embryo;
• Election and preparation of the receiving mare, and, finally;
• The transference for receiving mare uterus.

The giver mare is covered or inseminated next to the ovulation, and the ovulation day appointed as day 0. In day 7 or 8, the mare giver uterus is washed for the embryo harvest. This is located and identified through a magnifying glass and, after, it can be transferred to a receiving mare in two ways: surgically, through an incision in the flank, or not surgically through a pipette. Nowadays, 95% transferences of embryo are made by the not surgical method.

ADVANTAGES OF ITS UTILIZATION

The biggest reasons for accomplishment of embryo transference are:

• Infertile givers mares, resulting in impossibility to lead the embryo to the term;
• Physical problems in givers mares, as laminite or pelvic trauma that also culminates in the impossibility to lead the embryo normally;
• The desire to keep the giver mare in competitions, and to be possible to conciliate the sporting career with the reproductive career;
• The increasing desire for the productivity of a mare for a more than one filly per year.

The accomplishment of the technique of embryos transference also brings other advantages, such as:

• The obtainment of a bigger amount of superior mares descendants, with a high genetic value, making the genetic female influence in the flock more remarkable;
• The obtainment of animals gestations in hippic competitions, allowing to keep in parallel the sportive activity of the giver mare;  
• Obtainment of colts from older valuable mares, that can have difficulty in the suckling and in the gestation or they  have already an uterine degeneration and cervical and vaginal injuries;
• Obtainment of colts from two years old mares, so in this stage the gestation is contraindicated and can harm the filly development;
• Obtainment of under fertile mares, that for some reason had been disabled of procreate;
• Obtainment of mares gestation that stop lately in the station;
• Get one or more colts of mares that are commercial objects transaction, making with these mares, before being sold, produce embryos interesting to the ex owner.

RESULTS

The results of gestation by embryo transference modify in accordance with the association of two factors:

• Embryonic recovery tax and;      
• Gestation tax after the transference of this embryo for the receiving. In relation to the embryonic recovery tax, this is around 60% in other words, of each 100 uterine washing accomplished, they can find embryos in about 60 attempts.

The main factors that can affect this tax are, amongst others:

• Harvest day, the ideal is accomplish in the 7 and 8 days and after the ovulation;
• Sire semen fertility, where sires with the best fertility increase the embryonic recuperation chance. And because of this the frozen semen, due its minor fertility, offers worst embryonic recuperation results;
• The mare Reproductive history where the embryonic recovery tax is lesser in old or under fertile than in fertile young mares and;

Already in relation to the embryonic implantation tax, this has been around 65%, in other words, of each 100 embryo transferences accomplished, around 65 results in gestation.

The main factors that can affect this tax are, amongst others:

• The technician ability who accomplished this embryo transference;
• The found embryo quality, where logically embryos in good condition offer better gestation results;
• The giver age, where elderly givers normally take worst gestations taxes;
• The receiver reproductive quality, where should use in preference receivers evidently fertile, determining in this way the gestation results.

Therefore, must be considered, in average, 3 attempts (3 giver inseminations) to get a gestation in the receiver, therefore as it was explained previously, nor all ovulation with insemination results in fertilization; nor all recovered embryo in the washed uterine; nor all collected embryo is viable and nor all viable embryo transferred results in the receiver gestation.

CONCLUSIONS

The embryo transference has acquired more and more sympathizer that look for in this technique a way that to speed the election process through the productivity increasing of the superior genetic mares. Nowadays, the Paulista Mangalarga, Marching Mangalarga, Quarter Horse, Appaloosa, Paint Horse, Arabian, Brazilian equestrianism, allow and use in increasing amounts this technique of artificial reproduction.

It is enough to cite that of the 643 coverings communicated in 1999 sum station in the Brazilian equestrianism race, 123 of them were referring to the communications of embryo transferences (19,10%), what means that 1 in each 5 born young horses of equestrianism Brazilian race is a embryo transference result and deriving of superior genetics mares. And even Known that the biology nor always follows mathematical rules, at least the transference perhaps allows that the creators dream that use it is a little next to the reality.

Dr. Eduardo Onoe
Veterinarian Doctor CRMV SP 7215
Echinus Reproduction Center TOK