Staff members from the Bronx Zoo and Colorado State University announced that a surrogate bison has given birth to a healthy male calf. The birth took place at the zoo on June 20, said experts, who further affirmed that the calf is of a pure Yellowstone bison breed.

Efforts for the same started in October 2011 when a group of researchers being led by Jennifer Barfield, who is a reproductive physiologist, brought embryos from federal facility of the university. The embryos were properly washed, so that no impurities remain and then later it was being implanted in surrogate mothers.

After two months, medical evaluation was being carried out. It was found that one of the surrogate mothers is pregnant, and the same bison was later taken to the zoo, which is in New York. In order to save the bison from disease, it was not kept at the zoo at the time of reproduction.

Researchers were of the view that it is the first time that a pure bred bison has been born through surrogacy. "The Bronx Zoo played an important historical role in the recovery of the American bison. By establishing a pure herd the zoo will be, in essence”, said Pat Thomas, who has been positioned as general curator at the zoo.