Natural servicing of mares by stallions is a highly uncommon practice these days. Several new techniques have been developed to impregnate mares. Some are fairly straightforward, but others are more complicated and costly.
The most commonly used technique to impregnate mares is by artificial insemination (AI). The semen of stallions is collected at stallion stations, processed to multiple samples and dispatched in cooled conditions. This opens a window to freeze semen of stallions that are actively competing in the sport, stationed abroad or have passed away.
In recent years embryo transfer (ET) has grown enormously in the horse breeding world. This process involves the transfer of a donor mare’s embryo to a recipient mare. This would be a viable option for mares competing in sports or older mares that are difficult to get in-foal or don’t catch at all. It also makes it possible to produce more than just one foal a year by the same mare. The embryo has to be flushed out on the seventh day following fertilisation. If the embryo is transferred to the recipient mare within 24 hours then chances of success are the same as when the embryo is transferred immediately. About every other flush (50%) is found to contain an embryo. Taking into account the number of embryos that die during the first six weeks in normal gestations, ET is expected to produce around one live foal per four ET flushes.
OPU and ICSI
The most innovative reproduction techniques are OPU and ICSI. With OPU (ovum-pick up), egg cells are retrieved from the ovary under ultrasound guidance. The egg cells undergo the last phase of maturation in the laboratory. Next, they are impregnated in the laboratory by means of injecting one sperm cell (intracytoplasmic sperm injection, ICSI). Subsequently the fertilised egg cells are monitored to observe their development into embryos. The embryos can be frozen and stored in liquid nitrogen and either be stored, transported or transferred to a recipient mare. For genetically valuable horses for whom breeding is not a straightforward option, this ICSI technique can be the solution. In terms of financial costs however, the complex processes involved in ICSI make it rather pricey.