EVOLUTION OF KNOWLEDGE ABOUT OVARIAN PHYSIOLOGY AND ITS CONTRIBUTION TO THE APPLICATION OF REPRODUCTIVE BIOTECHNOLOGIES IN SOUTH AMERICA

As our understanding of ovarian function in cattle has improved, our ability to control it has also increased. Luteal function in cattle has been studied in detail, and prostaglandin F2α has been used for several years for elective induction of luteal regression. More recently, follicular wave dynamics have been studied and protocols have been designed to induce follicular wave emergence and ovulation, and the need to detect oestrus has even been eliminated. The addition of progesterone, estradiol, GnRH and equine chorionic gonadotropin (eCG) releasing devices has provided opportunities for fixed-time AI (IATF) and possibilities for achieving higher pregnancy rates. In embryo transfer programs, these same treatments have eliminated the need to detect oestrus, allowing fixed-time embryo transfer (TETF) and the initiation of superstimulatory treatments regardless of the day of the estrous cycle. Taken together, the new protocols have facilitated the application of assisted reproductive technologies, and this is especially true in South America. Over the past 20 years, the use of AI in South America has increased, due in large part to the use of the IATF. The use of the IATF has been multiplied by more than 10 times in Brazil, with more than 11 million treatments in 2016, which represents 85% of all AI. Similar trends are occurring in Argentina and Uruguay. In vivo embryo production produced by superovulation (DIV) has remained relatively stable over the years, but in vitro embryo production (PIV) has increased dramatically in the last 10 to 15 years, especially in Brazil, where More than 300,000 PIV embryos were produced in 2010. Worldwide, over 990,000 bovine PIV embryos were produced in 2017, of which more than% were produced in South America. The use of assisted reproductive technologies has facilitated the spread of genetic improvements and increased reproductive performance; These practices are spreading to many South American countries.