Scientists have successfully implanted a genetically pure embryo into a commercial bison leading to the birth of a purebred Yellowstone calf, which is now living at the Bronx Zoo.
This is great news for the park - as around 40 per cent of the natural herd suffer from brucellosis, which can cause pregnant animals to miscarry, meaning the future of the most world's genetically-pure breed could be at risk.
The zoo and Colorado State University announced that the surrogate bison gave birth to a healthy male calf at the zoo on June 20.
The embryo was taken from a Yellowstone bison, kept at the university in October, checked for diseases, and then implanted in the surrogate, the Daily Mail reported.
While many bison have been bred with cattle, Yellowstone National Park has one of the world's largest and most genetically-pure bison herds.
But concern about the disease has prevented the animals from being taken out of the park to reproduce.
Wild bison herds use to roam across American, until humans almost wiped them out in the centuries leading up to the early 20th century.
According to PopSci, many bison have some cattle genes, but Yellowstone's bison are "genetically uninterrupted."