In vitro embryo production (IVEP) is used to develop high-quality genetics associated with intergenerational genetic gain. It is characterized by acquisition (in vivo or post-mortem) and maturation (MIV) of oocytes from donors, followed by fertilization (FIV) of matured oocytes and culture (IVC) of embryos, which are then sent to transferred or cryopreserved. Even with extensive knowledge on IVEP, some biochemical and hormonal regulations that involve embryonic development are still unknown, leading to a low overall efficiency of the biotechnological process. Although in vitro developed embryos have a lower quality than that produced in vivo, in terms of resistance to challenging events, IVEP presents itself as a potential biotechnology. In cattle breeding, reproductive biotechnologies are key to increase and improve the genetic improvement of the herd, associated with productive and reproductive efficiency. In this article, the steps and strategies of IVEP and its contribution to reproduction in the cattle sector are discussed.
The application of Fixed Time Artificial Insemination (FTAI) protocols has strongly boosted artificial insemination in Brazilian bovine herds. The control of the estrous cycle with protocols based on progesterone and estrogen involves synchronizing the emergence of a follicular wave, controlling the progesterone phase, and inducing ovulation in a synchronized manner. The increase in pregnancy rates starts with the preparation of the breeding season and the choice of protocols and females. Thereafter, based on the characteristics of the property and the lots of animals, small adjustments can be made to the hormonal protocols as needed. Finally, resynchronization can increase usability by allowing multiple inseminations within short periods. The search for new strategies is of paramount importance for the development of the FTAI protocol and the increase in final pregnancy rates. Thus, this review sought to highlight the main critical points and adjustments of the FTAI protocols and their applicability in the reproduction of beef cattle.
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