I think it's a good way to have a foal from a mare without having to stop her competition career.
The gestation period for a horse is 11 months, so you’re only getting one foal per year when you breed traditionally.
This process can be done on younger mares with no interruptions to their competition and training schedules.
The process not only keeps mares competing, but it allows stallions to cross continents. Frozen fertilized embryos from working polo ponies in the US are now being shipped to Argentina where they are carried by mares and then trained by some of the best polo trainers in the world. On the flip side, semen can also be frozen and shipped to the US.