What is the ruling on zakat for a horse farm designated for trade, none of whose horses have been sold for over a year, with the expenses of their upkeep and care being borne? And what is the value of the zakat due on them?

Horses prepared for trade are subject to zakat on their value if they reach the nisab (85 grams of gold or 595 grams of silver). The horses are to be appraised, and a quarter of one-tenth (2.5%) of their value is to be given as zakat upon the completion of a full Hijri year. The fact that none of them have been sold or their expenses do not affect the obligation of zakat.