RESUMO
Transvaginal ultrasound-guided oocyte retrieval (commonly called OPU) and in vitro embryo production (IVP) in cattle has shown significant progress in recent years, in part, as a result of a better understanding of the full potential of these tools by end users. The combination of OPU and IVP (OPU-IVP) has been successfully and widely commercially used worldwide. The main advantages are a greater number of embryos and pregnancies per unit of time, faster genetic progress due to donor quick turn around and more elite sires mating combinations, larger spectrum of female age (calves, prepuberal, heifer, cow) and condition (open, pregnant) from which to retrieve oocytes, a reduced number of sperm (even sexed) required to fertilize the oocytes, among other benefits. OPU-IVP requires significant less donor preparation in comparison to conventional embryo transfer (<50% of usual FSH injections needed) to the extent of no stimulating hormones (FSH) are necessary. Donor synchronization, stimulation, OPU technique, oocyte competence, embryo performance, and its impact on cryopreservation and pregnancy are discussed.
Assuntos
Recuperação de Oócitos , Sêmen , Gravidez , Bovinos , Animais , Feminino , Masculino , Recuperação de Oócitos/veterinária , Fertilização in vitro/veterinária , Oócitos/fisiologia , Hormônio Foliculoestimulante , Ultrassonografia de Intervenção/veterináriaRESUMO
Background: For the nineteenth consecutive year, the International Embryo Transfer Society (IETS) Data Retrieval Committee has global embryo transfer (ET) statistics to report. The goal of the IETS Data Retrieval Committee is to collect complete in vivo and in vitro embryo collection and transfer statistics from every ET practitioner in the world. Although, not all the ET activity that is performed world-wide is included in this report, it is the best report available and gives us a good indication about the trends and directions of the activity different parts of the world. Review: The number of bovine in vivo derived (IVD) embryos collected/flushed worldwide in 2009 was 704,000 compared to 746,000 embryos in 2008. That's a 5.6% decline. However, the number of embryos transferred is down by only 0.5% (from 539,000 to 536,000). North America reported the largest downward slide. A depressed US economy coupled with the discovery of some lethal recessive genes in a popular breed of beef cattle are some of the main reasons for the drop in volume of ET activity there. The number of frozen IVD embryos transferred outnumbered fresh transfers by almost 50,000 (292,000 frozen and 244,000 fresh). The total number of transferrable bovine in vitro produced (IVP) embryos worldwide was 379,000 in 2009 compared to 331,000 in 2008. This represents a 12.7% increase in production. Brazil again leads the global field of in vitro embryo production and transfers. The total number of IVP embryos transferred worldwide was 307,845. The efficiency of frozen IVP embryos will likely determine the acceptance of in vitro technology by other countries. So far, the majority of the IVP embryos transferred have been fresh, not frozen (i.e. only 7% of the IVP embryos transferred in 2009 were frozen). However, that data varies according to different regions of the world. For example, Asia and Europe both reported that 58% of the IVP embryos transferred in those continents were frozen. That's very similar to the percent of in vivo embryos transferred that are frozen in those same regions. Consequently, North America (primarily the US) and South America (primarily Brazil) both reported that only 4% of the in vitro produced embryos that had been transferred were frozen. Including in vivo and in vitro fresh and frozen, there were 49,465 more bovine embryos transferred in 2009 (843,862) as compared to 2008 (794,397). This represents a healthy 5.9% increase. Many data collectors could not separate beef and dairy embryo production so no attempt was made to estimate that ratio on a global basis. If all species are considered including in vivo and in vitro production, there were 1,139,981 viable embryos collected / produced and 872,120 embryos transferred into recipients. Equine ET activity was down slightly in 2009. The number of reported flushes (36,971) was down by 7300 compared to 44,338 in 2008. However, the number of transfers (24,491) was only down by about 2500. Small Ruminant ET activity was up by about 40% over the previous year (36,199 transferable embryos were collected in 2009). Australia was the clear leader in ovine embryo production and transfers. Swine ET activity is very low worldwide. Conclusion: The volume of ET activity reported from all the committee's regional data collectors indicates that the embryo transfer industry is doing well. Is also important to note that this report does not include every country's statistics, and very few, if any, country has 100% of its activity represented; however, it is the best world-wide report available about the commercial embryo transfer business.