Zakat On Selling Animals
I think whatever profit you’ve made from that, it would still be below Nisab ( whichever category of Zakat is applicable here ). If you start doing cat rearing and selling business, then it can become a source of production income for you for which you can calculate Zakat at 5% of your value addition ( since both labour and principal investment are involved here ) if it is above Nisab threshold. But other than that, it would be your wealth and you can include this amount in your year-end Zakat calculation of wealth.