Hilchos Bikkurim 10:7

One must give first shearings from hybrid animals, a koi (which is a type of animal that we don’t know if it’s wild or domesticated) and an animal that has a fatal condition. If one shears a dead sheep, first shearings need not be given.

Hilchos Bikkurim 10:8

If someone put first shearings aside and they got lost, he must replace them until they’re given to a kohein. If someone declares that all of his shearings should be considered first shearings, his statement is effective.