• The ability to breed mares that are older or have problems carrying a foal to term (the embryo recovery rate is likely to be low).
• For highly valuable mares, the ability to reconcile breeding with a competitive career.
• The possibility of producing several foals from the same donor mare in the same year (reducing the generation gap and obtaining genetically superior offspring).
• The ability to breed two-year-old mares that are promising but have yet to reach the maturity required to maintain a pregnancy (N.B.: not all mares have reached puberty at this age and the recovery rate is often low).
Developing the embryo transfer technique will involve reducing the technical constraints and increasing productivity.
• Synchronization of the recipients, which is a very costly process (maintenance and gynecological monitoring of a herd of recipients).
• Very close gynecological monitoring of the donor.
• A team of qualified and experienced handlers.
• Recovery and transfer equipment (sophisticated laboratory equipment and single-use and/or sterilized supplies).
• Need for appropriate facilities (transfer laboratory, suitable restraining stocks).
Two possibilities are being studied with a view to reducing certain constraints:
• Embryo freezing, enabling embryo recovery and transfer to be dissociated (in terms of time and location). This technique would make it easier to manage synchronization of the recipients, and facilitate commercial exchanges and the preservation of endangered breeds (by creating an embryo bank).
• The superovulation technique, in order to recover several viable embryos per attempt and thus increase productivity.
These two possibilities are topics of scientific research and are not currently applicable on a routine basis in the field, although researchers are progressing towards this aim.