I would try to make it easier for your young (?) roosters and cut the fluff, b/c young rooster sometimes have problems with holding the balance while finding the right spot. Even my tiny, non-fluff birds have sometimes problems... the hens are in general not that excited to be hopped by a young rooster. If an older, higher ranking rooster is around they sometimes don't cooperate that much, regardless if the older rooster is okay with it or not.
O/c you can reduce the fluff by select breeding.... This is the way the got the fluff in the first place. But I would monitor the meat quality, in some breeds the fluff and the meat quality seem to be connected. I have no first hand experience with that, my birds do not get fat, but personally I think that the way you feed the birds has more to do with the meat than the fluff.
But maybe your Bielefelders are just not willing to take the risk of been beaten up by one of your other roosters.
Temperaments are diffent. I have had roosters that took every risk and didn't mind to loose some feathers, others made sure that the dominat rooster was buisy on the opposite site of the allontment before getting close to a hen.
The problem of the bottleneck effect and inbreeding depression is something most pure breeds (old and new) struggle with in Europe. The number of chicken owners and breeders are plummeting and so are the number of purebred chicken and chicken breeds. But not only chickens are at risk, other livestock and plants too. We loose our diversity to the gen hunters, factory farms and the big agrar cooperation.
GFF imports rare breeds, that means that the gene pool here is very small and out of that small pool they take a relativ small number of birds...to select for the breed typical and not related birds is a difficult task.
On the other hand it is always difficult to breed show quality and without a written standard, not possible.
...and Bielefelders are not Hybrids they are a breed, a breed that is 80 years younger than most of the European breeds, but a breed.
As I said some breeds may have a longer tradition, but the few paintings and written descriptions we have from our chickens are very vage and it could be a coincidence. From a once very common breed of the Tiroler Spitzhaube i.e. we have only one bluerred photo. One hen in the backround of photo that shows a proud farmer and his priced bull ... and a chicken fanciers who looked in every backyard and on every remote farm in Tyrol to find birds like her to bring this breed back to life. Did the original breed have the same genes/qualities like the new revived one?
It is impossible to know that.
