How can the Zakah due on camels prepared for racing be calculated?

A 2 : There is no Zakah payable on the camels prepared for racing, since they are prepared for use and they are fed with fodder and are not Sa'imah, i.e. Cattle that are left to graze freely without giving them fodder. However, when the owner of these camels wins prizes from racing and they reach the Nisab (the minimum amount on which Zakah is payable) and a full lunar year has passed since owning this money, Zakah becomes payable on that money.