The ruling on paying the zakah of livestock that was purchased and has not reached the end of a lunar year

Question:
Is it permissible to pay the zakah on livestock before the year has passed over them? And if I sold five sheep and bought five in exchange for them, do they become subject to zakah if the year passes over them?

Answer:
If a man buys sheep, he pays their zakah after the year has passed over them. If the year has passed over them and he has bought them, he pays their zakah when the year has passed over them, which is the zakah of sheep. The same applies to camels, and the same applies to cattle: when the year has passed over them, he pays their zakah as the zakah of livestock.
And if a man sells sheep for sheep, the period is calculated based on the year of the first batch. When the year of the first batch is completed, he pays zakah on the second batch. The same applies if he sells camels for camels, or a cow for a cow. However, if it is for trade, where he sells and buys for trade, the zakah of money applies: he appraises his sheep and similar goods, appraising them so that he may pay their zakah as the zakah of trade.