Nearly 30 select mares, mostly from the lines 104 a, 173 and 3615, are in service at Hof Thormählen. To safeguard the genes of the sport mares for sale, young mares are bred when they are three years old and only introduced to sport after they have had a foal at the age of four. In the case of especially valuable broodmares, embryo transfer is also utilized.