Large-scale programs for recipients of in vitro-produced embryos

ABSTRACT

In vitro embryo production (IVEP) has become an accessible option for meat and milk producers, and Brazil is now the leader of IVEP worldwide. Recipient females represent one of the most significant costs in embryo transfer (ET) programs. Thus, hormonal protocols may increase the proportion of suitable recipients to receive embryos and improve the efficiency of IVEP program s. Besides improving the amount of available recipients, it is important to select high quality animals. Due to the great demand, the type of females that were considered ideal for ET has become scarce, especially for large-scale programs. Therefore, new approaches have successfully emerged, as the use of Nelore cows recently calved as embryo recipients. For being the most numerous category in Brazil, these animals can be acquired for fair prices. Embryo production from slaughterhouse ovaries also represents an innovative strategy for large-scale IVEP. With the use of sorted sperm and large amount of pregnancies, is has become an interesting alternative compared to AI. In this article, recent advances in embryo IVP are discussed, as well as some of the most used hormonal protocols for estrus synchronization of recipients in large-scale IVEP programs.