I have a friend who breeds black Jersey Giants. She takes the boys out to the farm where my breeder birds and extra Langshans are. We had a black JG running with the black Langshans until processing day. I always had to look for the feathered legs & feet to tell which was which. Now we only have the Langshans left which makes things easier.
Giants were developed using Langshans, they don't have the wonderful tails though. I always tease my Giant breeding friends about when are they gonna get some real big birds (in this case defining big with height), then politely decline when they offer to go grab the scale. LOL