Development of the world farm animal embryo industry over the past 30 years.

Embryo technologies have been used over the past three decades globally in most relevant farm species. From a sanitary perspective, embryos collected in vivo have long been recognized as the safest way to trade livestock germplasm, as long as the IETS washing and, if recommended, trypsin-decontaminating procedures are adopted. On the other hand, a number of questions have been raised about the safety of embryos produced in vitro, frequently inhibiting the international commerce of these embryos. In the major players of the world embryo industry, however, in vitro embryo production (IVEP) has become the technology of choice in cattle, and its adoption on a large-scale has caused the world embryo records to be scaled up exponentially. Nowadays, over a million cattle embryos are produced and transferred worldwide, of which approximately 80 % are in vitro produced. Moreover, the same trend is currently being observed in small ruminants and horses. In the present review, we describe the development of the world embryo industry over the past few decades and speculate on how this contributed to the apparent dichotomy between the perceived and the actual risk of transmission of infectious diseases by the transfer of in vitro produced embryos. Additionally, we discuss the future trends of the international market of livestock germplasm, in the light of the changes driven by emerging embryo technologies.