From Wikipedia, the free encyclopedia. Dan M. "Buck" Brannaman is a horse trainer and a leading practitioner within the field of Natural horsemanship, which is a philosophy of working with horses based on the idea of working with the horse's nature, using an understanding of how horses think and communicate to train the horse to accept humans and work confidently and responsively with them. One of Brannaman's stated goals is to make the animal feel safe and secure around humans so that the hors ...