Tall Grass Bison, the largest bison producer in Iowa, maintains their herd of over 300 grass-fed bison on 1000 acres "as close to natural conditions as possible." The animals are free-range and graze on native prairie grasses; no corn or other grains are fed. Herds are managed for natural family order, an evolutionary development that minimizes stress, the precursor of pathogens, illness and tough meat. Healthy stress-free lives mean they have never needed nor been given a shot or antibiotics in their life.