Is zakat obligatory on money invested in livestock in partnership with farmers, and if so, how is it calculated?

This issue is called "mixing of assets" (khaltat al-a'yan), which occurs when two or more individuals share ownership of a number of livestock that reaches a nisab (taxable threshold) or more. In such a case, it is zakat-eligible as the property of a single person if a hawl (full lunar year) has passed. It is not a condition, according to the Shafi'i and Hanbali schools, for each partner's share to reach a nisab; rather, zakat becomes obligatory if the total number of livestock reaches a nisab. Others hold that each partner must possess a nisab for the mixing to be effective.

However, if these livestock are for trade, there are two opinions regarding their zakat: 1. They are subject to trade zakat if a hawl passes and their value reaches the nisab of livestock. 2. They are subject to zakat on pastured animals (zakat al-sawm), which is the new opinion of Malik and Al-Shafi'i. If the livestock do not reach the nisab for livestock but their value reaches the nisab for trade goods, then they are subject to zakat on trade goods.