Embryo transfer has proved to be a powerful technology in genetic improvement of farm animals, primarily to propagate the genes of females of superior pedigree. . In cattle, particularly in the dairy industry, breeding programs have been developed to promote genetic progress by strategic use of elite females through multiple ovulation embryo transfer (MOET) programs. In addition to conventional methods to produce embryos available for transfer, new technologies that produce embryos after cloning by somatic cell transfer or transgenesis are available but not widely used commercially.
Embryo transfer protocols have also been extensively used in research critical to understand several areas of biology and medicine, such as fetal-maternal interactions, models of human and animal diseases, production of transgenic animals to produce therapeutic proteins for people, etc. However, this discussion is restricted to the principles and methods currently used in commercial embryo transfer of farm animals. Except in horses, embryo transfer programs in most mammals include administration of drugs that superovulate females to allow the probability that multiple embryos are collected per procedure. Globally, it was reported in 2012 that 699,586 bovine embryos were collected from superovulated cows, and 443,533 bovine embryos were produced via in vitro fertilization procedures.