Reproductive Technologies for Horses Essay

In recent decades, due to the rapid development of technology, the economic requirements for the quantity and quality of horses bred have changed significantly. Directions for improving the livestock of individual horse breeds according to economically useful traits currently require substantial adjustment. However, the turnover of generations slowed down compared with other animal species, prolonged pregnancy, the high cost of outstanding animals complicates breeding work, inhibits the pace of the breeding process in the rocks. The methods of accelerated breeding of especially valuable animals are becoming increasingly important for the improvement of horse breeds. In particular – the transplantation of early embryos. The issues in horse breeding solved by embryo transfer technology are similar to problems in other branches of animal husbandry. This is an increase in the intensity of propagation, the staging of genotypes of prominent females, the improvement of breeds with a limited gene pool, the preservation of original mutations.

From the second half of the twentieth century, a new scientific direction began to develop rapidly – biotechnology. The first successful experiments of American scientists in obtaining the offspring of farm animals by embryo transfer gave an excellent breeding tool that makes the most effective use of the genetic potential of females. The first successful embryo transplantation was carried out in 1890 by V. Heape with rabbits (Betteridge). It was performed by slaughtering a female donor and a complex abdominal surgical operation of a female recipient. As a result, we received two live normally developed rabbit-grafts. Until the end of the 40s – the beginning of the 50s of the current century, work on embryo transfer was carried out extremely rarely, and then only on laboratory animals and for educational purposes. In methodical terms, researchers, as a rule, repeated Heape’s experiments.

However, despite some successes, the method of transplanting in those years could not be recommended for widespread introduction into the practice of horse breeding. This is due to the low primitiveness of the transplanted embryos were anti-peristaltic contractions of the myometrium of recipient mares, caused by inadequate stimulation of the receptors of the cervical canal; imperfection of instruments used for transplantation; inferiority of the composition used for transplants environments. Further work to improve the technology of horse embryo transplantation allowed us to slightly increase the effectiveness of transplants.

Everything was much more complicated with horses. The first difficulty for specialists was the futility of attempts to induce multiple ovulation in mares by hormonal methods. The maximum that could be expected is the production of 2-3 ovulations per 1 sexual cycle (for comparison, up to 30 embryos can be obtained from cows per cycle). This specific feature hampered research, requiring much more time to test hypotheses and obtain reliable results. However, the technology was developed (first surgical – in England, then microsurgical – in Japan and, finally, non-surgical – again in England). In horse breeding, the successful experience of embryo transplantation and the birth of healthy offspring was first carried out in Japan in 1974 experiences Oguri and K. Tsutsumi (Betteridge).

Transplantation of embryo is a method of accelerated reproduction of highly productive animals by obtaining and transferring one or several embryos from highly valued animals (donors) to less valuable animals (recipients). The use of transplantation makes it possible to receive from one genetically valuable female ten times more offspring. The most suitable for the transplantation of embryos are small animals: cows, horses, and sheep (Reenskkaug). In the world practice of animal husbandry, the method of embryo transplantation is mostly used in dairy and beef cattle breeding. Using recipients to transplant embryos obtained from a single selected donor horse, it is possible to increase the number of its descendant tens and hundreds of times. Theoretically, at least few foals can be obtained from a genetically outstanding donor horse in her entire life. Huge progress has been made in the transplantation of cattle embryos, as a result of which this method has taken a firm place in modern breeding programs (Scherzer). The method of transplantation together with artificial insemination is considered as the basis of modern biotechnology for the reproduction of highly productive breeding animals. The technology of embryo transfer includes a number of successive stages: selection of donors; superovulation with donors; selection of producers and insemination of donors; embryo extraction and evaluation; cultivation or freezing of embryos; selection and training of recipients; embryo transfer to recipients; assessment of the results of transplantation.

Further development and widespread introduction of biotechnology methods into horse breeding will depend on the availability of qualified specialists, economic incentives, strict regulation and the correct solution of organizational issues. The International Embryo Transfer society (IETS) has tried to register embryo transfer world wide for many years. However, it is rather difficult because not all breeders and horse owners register this process. IETS has a report that is presented by Data Retrieval Committee that has the data on horse. It show the number of embryo transfers. The leaders in this process are France, Italy and Spain (Perry). The centralized system of cryobanks is used by many breeders and horse owners. The embryos, oocytes, sperm, cell lines and other biological material are conserved to reproduce, if necessary, individuals of any species, breed or combination of pairs with the desired genotype. The use of embryo transfer methods, in this situation, will exempt the outstanding mares associated with pregnancy from withdrawing from the sport for a long period of time. It will allow receiving offspring from them without harm to their future sports career.

References

Betteridge, Keith J. “A History Of Farm Animal Embryo Transfer And Some Associated Techniques”. Citeseerx.Ist.Psu.Edu, 2003, http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.616.6078&rep=rep1&ENGINE=pdf. Accessed 11 Nov 2018.

Perry, George. “STATISTICS OF EMBRYO COLLECTION AND TRANSFER IN DOMESTIC FARM ANIMALS”. Iets.Org, 2016, https://www.iets.org/pdf/comm_data/IETS_Data_Retrieval_Report_2016_v2.pdf. Accessed 11 Nov 2018.

Reenskkaug, Astrid. “Embryo Transfer In Horses”. Huveta.Hu, 2014, http://www.huveta.hu/bitstream/handle/10832/1274/ReenskaugAstridThesis.pdf?sequence=1&isAllowed=y. Accessed 11 Nov 2018.

Scherzer, Jakob. “Artificial Insemination And Embryo Transfer In Mares”. Vetfolio-Vetstreet.S3.Amazonaws.Com, 2011, http://vetfolio-vetstreet.s3.amazonaws.com/f6/761ac0a7fb11e087120050568d3693/file/PV0711_Scherzer_CE.pdf. Accessed 11 Nov 2018.

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