New perspectives in assisted reproductive technologies in cattle
The use of assisted reproductive technologies in cattle is been increasing in the past few years. Fixed-timed artificial insemination (FTAI) procedures are responsible for 85% of all artificial insemination (AI) done in Brazil. Despite the numbers of in vivo derived (IVD) embryos tended to decrease in the last 10 years, in vitro production (IVP) of embryos has increased significantly, with more than 57% of all IVP embryos in the world produced in Brazil. These biotechnologies have helped to substantially improve reproductive efficiency in beef and dairy cattle. In relation to embryo transfer, production of in vivo derived (IVD) embryos remained relatively stable, with average production of 30-40,000 embryos per year, whereas in vitro production (IVP) of embryos had a substantial increase, from about 12,500 IVP embryos in 2000 to more than 300,000 IVP embryos after 2010. Inside this picture, FTAI remains growing for both, dairy and beef cattle, although, there are new possibilities to get even better efficiency. The use of GnRH and new approaches to help this efficiency were reported recently. In addition, there is much more room for improvement in other reproductive technologies, since there are several reports of high pregnancy loss and high peripartum loss, when IVP embryos are used, and even more dramatic for cloning. This review aims to update the readers with new data regarding assisted reproductive technologies.