The 19th century saw the beginning of research on mammalian reproductive
control, gamete cells in male and female animals, cryopreservation, semen collection and analysis, and artificial insemination (AI) in several animal species. Ivanoff initiated the first horse research in Russia. Subsequently, scientists from various nations have studied assisted reproductive technology (ART) in bees and other animal species. They have also examined substances and mechanisms that prevent oxidative stress and freezing diluted semen using various techniques. Researchers have previously studied sperm extraction, evaluation of semen, semen extenders, and various chemicals
added to extenders that protect semen against freezing damage. Semen is
utilized either fresh, chilled or, to a lesser extent, frozen in equine medicine.
Commercial horse breeders find it easier to do their jobs when semen is used in chunks, regardless of the method used. Because a single ejaculate can be used for artificial insemination in multiple mares, and because a genetically superior stallion’s semen can be readily stored for a year or even several years.