Broken Kettle Grasslands is starting the herd with 28 animals from the Slim Buttes Project Herd, which currently resides at Lame Johnny Creek Ranch near Wind Cave National Park outside of Rapid City, South Dakota. The Slim Buttes Project herd is owned by the Conservancy but the animals originally came from the Wind Cave National Park, a closed breeding herd since 1916, having started with 14 animals from the Bronx Zoo and six from Yellowstone National Park. The Slim Buttes Project Herd has been supplemented twice from the Wild Cave herd.
The Conservancy has continued to manage this herd as a closed breeding herd. The herd currently tests as a genetically unhybridized herd, meaning that cattle genes are not present. At the end of October 2008, Broken Kettle Grassland will receive 28 animals from the Slim Buttes Project Herd.
The Conservancy will continue to work closely with Texas A&M genetic researchers to ensure genetic vigor as the herd grows in both locations. Based on available science, Texas A&M recommendations and further genetic testing, the Conservancy plans to continue this genetic stock at other Conservancy preserves that are preparing to introduce bison in their management plans.