Effective programs for bovine embryo transfer in Bos taurus and Bos indicus cattle.

The main objective of implementing embryo transfer programs in beef operations is to accelerate the rate of genetic progress in the herd. The main factors that affect the use of this technology are related to nutrition, management, category and breed of the recipients and the estrus synchronization programs implemented. As a result of research conducted over the last 30 years, recipient utilization has increased by applying protocols that synchronize ovulation and allow for embryo transfer without the need for estrus detection, usually referred to as fixed-time embryo transfer (FTET). Although these protocols have performed adequately for several years, recent attention has been directed to the effect of estrus expression, proestrus length and restriction to some hormonal treatments in some countries. The experiments reviewed herein demonstrate that several programs can be effectively used today to obtain high pregnancy per ET (P/ET) and reduced pregnancy losses, especially in recipients receiving in-vitro-produced embryos.