Yes you can breed them. You can use other marans varieties to cross on them. If you cross feather legged Copper Blacks on them, you will eventually end up with a flock of both golden cuckoo and silver cuckoos. You could choose whichever color you like best, and concentrate on better foot feathering. It would probably keep popping out silver and golden cuckoos for several generations however. It would probably darken your eggs too, as well as add feathering to the legs. If you crossed a CBM roo on your cuckoo hens, all the barred offspring would be roos. The pullets would not carry the barring gene and would be black or copper black. If you cross a cuckoo roo on CBM hens, you would get both sexes barred, but the roos would only have one copy of the barring gene instead of two. It would not be possible to tell them apart until they showed secondary sex charachteristics. Then you could cross the best feather legged roo on your best, darkest laying barred pullets, and choose the next generation roo as one with lighter overall color and a larger head spot when he hatches, more typical of a homozygous barred/cuckoo roo. If you cross that roo on barred girls, you should be all barred/cuckoo all the time, and your roos should be always homozygous for barring. Good luck!
