In Peru, there has been an introduction of new sheep breeds in order to reorient the production of this species, towards products of greater value and demand, which has taken on greater importance in the last 10 years. Thus, for the importation of these embryos it is required to comply with the strict sanitary regulations and quality control in the process. The objective of the study was to evaluate the embryonic survival of cryopreserved ovine embryos and transferred in one step to recipients located in two ecological environments. The ovine embryos (n = 190) cryopreserved were imported from Australia and used using the one-step freezing method for direct transfer. The number of embryos per breed were Dohne Merino (n = 70), East Friesian (n = 70) and Dorper (n = 50). The embryos were transferred surgically (ventral laparotomy with laparoscopic help) into the uterine horn ipsilateral to the ovary with the functional corpus luteum. Crossbred recipient ewes (East Friesian x Barbados Black Belly and Corriedale x Criollo) were synchronized in two ecological environments; Peruvian Coast (Trujillo, at sea level) and central Andean mountains (Ayacucho, 3 704 masl) respectively. The sheep embryos were distributed according to the number of recipients available in each ecological environments; Peruvian Coast (n = 150) and central Andean mountains (n = 40). Our criterion for determining embryonic survival was based on the birth of a live lamb. The results were analyzed by the Chi square test in the contingency table and subdivision of the contingency table. The overall rate of pregnant recipients was 43.15%. The survival rate of the embryos in the two ecological environments was statistically different (p <0.05) between Peruvian coast (37.33%) and central Andean mountains (50.98%). The East Friesian breed showed the highest birth rates in two ecological environments, Peruvian coast (50%) and central Andean mountains (80%). The cryopreservation of embryos for direct transfer in sheep, is a repeatable and simple technique and with very good efficiency to achieve birth lambs in two ecological environments of Peru. Therefore, it allows the introduction of new breeds of sheep with high productive potential, minimizing costs.

The use of reproductive technologies in the reproduction of the domestic animals has different objectives, between the most important uses are the prevention of diseases transmitted via natural mating, the optimization of the reproductive management, the more economic interchange of genetic material, the development of more efficient animal production systems, the generation of offspring with predetermined sex and genetic composition according to market requirements, the conservation of genetic resources and the increment of the rate of genetic gain in the animal populations; being this last application the one that has the most frequent and important usage and the most significant impact in the animal production industry. The importance of the reproductive technologies in animal improvement is because it allows us to achieve a significant increment in the reproductive rate of selected individuals (to get the maximum number of offspring per breeding animal), this makes possible to obtain high intensity and precision of selection and at the earliest age possible (reducing generation interval) resulting in the highest genetic gain per unit of time. From all the reproductive technologies developed, the artificial insemination (AI) in cattle is the most widely used technology globally and at national level in Peru, followed by the embryo transfer (ET) in cattle and by the AI and ET in sheep. From the design and usage of the in vitro embryo production and methodologies for the embryo micromanipulation it has started the development of a series of advanced reproductive technologies from a simple embryo bisection up to cloning of individuals, reproduction using stem cells and production of quimeras with cells genetically modified. In Peru is only in the last decade that the research and development and commercial application of reproductive technologies in the livestock reproduction has started with some advances in in vitro embryo production, embryo transfer, animal cloning, etc. with visible impact in the animal production industry and generating many challenges in order to increase its efficiencies and achieve its commercial use.