Your welcome, its very hard to understand the german sites.Thank you for highlighting that, i simply did not understand what was what in regards to the mammut bull, so to summarise a mammut bull is an RB with a long coat which is a trait brought out by the creator of Ironbulls RB's.
Correct me if im wrong ?
Do you have any pictures of Mammuts mother ? As i can only find one hit for a long haired american bulldog, and this suggests that it originates from AB x Collie to gain the long haired coat.
American Bulldogs carry the recessive gene for long hair just like rotties, GSD's and many other breeds. It can happen naturally although uncommon, its believed to be from St bernard being mixed in the lines at the time of the breeds creation (with rotties and AB's anyways). The dogs can carry the gene without expressing it because its recessive and you need two recessive for the trait to show in the dogs appearance. So the dogs can carry it around for quite some time until it meets another recessive and bam you have a few furry puppies.
ETA yes horses mother was from a German line of AB she is not a mixed breed, just a fluke that happened so she was sold to Ironbulls since the original kennel had no use for her because she was against the standard. With a lot of these breeds that carry the recessive gene if it does get expressed in a litter of puppies its kept very hush hush and sometimes the dogs are culled.