In a European study from Munich, Busa cattle (an old European breed) was found to be far more genetically diverse than many of the more modern European breeds available today. The study tested 1828 different cattle representing 60 breeds, 350 of those individuals being Busa cattle. When genotyping for "single-nucleotide polymorphisms", Busa cattle were found to have 14 unique strains. Most of the genetic diversity (that being non-artificially selected diversity) of domesticated cattle can be traced back to or attributed to Busa cattle. Currently there is some push towards a conservation program for this breed to help maintain the functional diversity of cattle worldwide.
As most domesticated breeds of bovine have been bred not to survive but for meat/milk production, the survival of this breed (smaller and less productive but far hardier and healthier) is fascinating. Perhaps the introduction of some of the Busa cattle's' genetics into the more specialized breeds can help to lower their health issues.
Article Link- https://www.sciencedaily.com/releases/2018/03/180328143255.htm
Additional Info- https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.14555