The World Federation One Stop Fiqh

Ruling 1939

If a person who must pay zakat on cows, sheep, and camels gives it from other wealth that he owns, he must give zakat on the animals every year as long as their number does not fall below the niṣāb. If he gives the animals themselves as zakat and their number falls below the first niṣāb, then zakat is not obligatory for him. For example, if someone who owns forty sheep gives zakat on them from his other wealth, then as long as the number of sheep does not fall below forty, he must give one sheep every year; and if he gives sheep as zakat, then zakat is not obligatory for him until the number of sheep reaches forty.