From: Rabbi Moshe Sofer
To: Rabbi David
A non-Jewish shepherd sheared an entire flock including an identifiable bechor, causing it to become mixed among the rest of the animals and its wool among permitted fleece. The Chasam Sofer permits the wool by selling it to a non-Jew minus one fleece's value and discarding that value, permits the animals by either giving one to a Kohen or uprooting them from their fixed location, and relies fundamentally on the principle that a non-Jew's testimony is disregarded, leaving doubt whether any bechor was actually mixed in at all.
Source: Shu"t Chasam Sofer YD §307