I was not talking about the Orp Roo. All I know is Cuckoo Marans are SILVER Based or they SHOULD BE but they are not Silver Cuckoos.... just Cuckoos.
I know 2 different breeders who have Cuckoos who use them to clean out the brassiness in there Whites. they use them cause they have Silver. My friend who has White Rocks said to me his White Rocks when taken to my White Orps will not throw a brassy bird. Because it is a Silver. So MAYBE your Cuckoo Marans do not have Silver. But this does. And we will find out won't we?