His horse herd included mares as well as stallions. EIPH occurs less frequently in stallions than mares or geldings. Mares and geldings can be pastured together. Stallions form and expand their harems by abducting young mares from their natal harems. Spanish custom also called for mounted troops to ride stallions, never mares or geldings. Budonny stallions stand on average , mares . In Spain, breeders commonly roach the mane of mares and foals. The mare has two mammary glands, which are smaller in maiden mares. A typical Mongolian herd consists of 15 - 50 mares and geldings under one stallion. The stallion mates with all his mares. Masturbation is common in both mares and stallions, before and after puberty. In order to be incorporated into the studbook, stallions and mares must pass rigorous testing. This results in large foals that can be difficult for the small mares to birth. Breeding this horse and descendants with Virginia mares led to larger size horses. The Russians closed the studbook in 1932 which included 287 stallions and 468 mares.