What is the ruling on Zakat when an employed herder possesses a specific animal that reaches the Nisab threshold by the end of the year without being separated?

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If an employed herder is given a specific animal (from the Nisab) to guard, and a full Hawl (year) passes while the animal remains with his own property, both the employer and the herder are considered partners (Khaleetan) concerning Zakat obligation due to blending (Khultah). The Zakat due from this partnership is taken from their pooled wealth, just as it would be taken from the wealth of a single individual. Imam Ahmad's apparent view is that the collector (Sa'i) may take the due amount (Fard) from whichever partner's wealth he chooses, regardless of whether this is necessitated by the specific form of the due item (e.g., one large sound sheep when one partner has small or sick ones) or if the required item is found entirely within one portion. This is based on the Prophet's saying: 'Whatever is shared between two partners, they must reconcile the due share equally,' and 'Neither what is separated should be gathered, nor what is gathered separated, out of fear of Zakat.'