What determines the ruling regarding 'Saum' (grazing/pasturing) and 'Al-af' (feeding) for offspring of mixed origin?

Primary text

The ruling concerning whether an animal is considered 'Sa'imah' or 'Ma'loofah' is based on the condition of the animal for which Zakat is due, not on its original lineage. This is evidenced by the fact that if the offspring of a Sa'imah animal is fed, Zakat does not become due, and if the offspring of a Ma'loofah animal is allowed to graze, Zakat becomes due upon it.