Guidelines for improving efficiency in equine embryo transfer programs

LOSINNO, LUIS; TOM STOUT; WILLIAM RICHARD ALLEN; PIETRANI, MELINA

Equine Assisted Reproduction

Independiente

Lugar: Bogotá; Año: 2019; p. 143 - 155

Currently, accumulated experience, both in empirical and scientific-technological knowledge, have set standards and expected results in commercial Embryo Transfer (ET) programs, which are generally known by the clients who put pressure on the professionals that provide these services.Moreover, from the Veterinarian´s point of view, these standards and results set the levels of efficiency that the system should have to keep up with the programs of ET worldwide, so as to be commercially competitive and economically viable.In commercial ET programs, recording the activities and procedures (mare´s records, medications, artificial insemination, treatments, flushings, embryo transfers, etc.) should be a common practice. It is difficult to perform a technical and objective analysis of a complex system if we do not have numerical data. If we just rely on impressions, opinions and intuitions which are not enough to carry out a system diagnosis, we will be unable to draw conclusions from possible failures and critical points to improve. Currently, available technology facilitates real time data processing, data loading, reports and online consultations, providing veterinarians a friendly and productive tool. All this processed information is critical to our system by helping to identify points to improve in order to optimize the efficiency.Despite there has been a considerable increase in ET results during the last 30 years, there are still significant losses regarding system economy, time, genetics, donor mare?s cycles, semen doses, client?s expectations, etc., that is, in efficiency. Even though the expected values of post transfer pregnancy rate depend on different factors such as type of ET program, breed, mares age, semen quality, nutrition management, recipient mares, staff training, and more, it is possible to establish expected values regarding embryo recovery rate (ERR), pregnancy rate (PR), an early embryonic loss (EEL) for commercial programs, where an overall efficiency equal to, or greater than 50% is considered acceptable. That is, a 70% ERR per cycle and a PR post-transfer higher than 70% (Efficiency = ERR x PR = 0.7 x 0.7 = 0.49), which is equivalent to two flushings per pregnancy as the expected theoretical value. Considering this, improvement can be, at least, a result of three simple concepts and analysis: 1) a systematic diagnosis of the program point by point; 2) control of small operational details; and 3) permanent professional update. There are also large-scale, stabilized commercial programs with efficiencies greater than 65% (approximately 1.2-1.5 embryo flushing?s per pregnancy) (Hartman, 2011; Cuervo-Arango et.al, 2018).If we consider in average a 70%, ERR rate, it means that at least 30% of the cycles in which we have inseminated the donors and prepared the recipients (semen, supplies, food, time, work) have been unproductive (negative flushing) and costs must be "absorbed" by the productive cycles of the same mare (or by something or someone else). If, in addition, we consider an average 70% PR, we can assume that 30% of the recovered and transferred embryos did not produce a pregnancy (which we expected). The reported EEL rates in ET programs until day 60 is 8-15%. Considering an average 10%, one in ten pregnancies detected between day 12-14 and 60 will be lost (but we do not know which one will be).No direct reference will be made in this chapter to historical, scientific, technical or methodological aspects of embryo transfer in detail, which already have been extensively covered in recent reviews. Our objective is to analyze some critical points of equine embryo transfer and their impact on efficiency rates. We will not consider in this analysis some critical factors that have a major impact on efficiency of ET programs such as semen quality, laboratory management, etc.; and we will only focus on some specific points recently studied in scientific publications.