Mark DeBoo stands as the third-generation steward of Diamond D Angus, a ranch deeply rooted in Montana’s Golden Triangle. The DeBoo family’s journey began in the 1950s with Charlie and Mary DeBoo, who were the only registered Angus breeders in the region at the time. Their acquisition of the influential bull, Pattern of Wye, set the foundation for what would become an enduring legacy.

In 1962, Don and Janet DeBoo—Mark’s parents—purchased their first registered Angus heifers and blended them with commercial cattle. From the beginning, they prioritized functional traits over fleeting industry trends, putting emphasis on maternal efficiency and structural soundness, often sourcing genetics from the historic Wye herd. This commitment to real-world functionality became the hallmark of Diamond D Angus.

After spending six years as a John Deere mechanic, Mark returned to the ranch in 1988 and helped usher in a new era with their first production sale in 1989. From selling 50 bulls out of an old barn to building a nationally respected program, Diamond D Angus has continued to evolve without losing its roots. By 2006, they transitioned to hosting fall production sales, offering forage-developed, long yearling bulls. Today, the ranch markets around 130 bulls and 100 bred females annually, with Diamond D genetics reaching across the United States, Canada, and Argentina.

Mark’s breeding philosophy remains focused on functional, maternal, and efficient cattle. The ranch’s standards are unwavering—culling animals with poor udders, bad attitudes, or foot issues, and refusing to trim feet to mask problems. Their cattle are designed to be trouble-free, moderately framed, forage-efficient, and long-lived, with many cows still productive well into their teens. Traits like calving ease, carcass quality, efficiency, and longevity are not just buzzwords—they are necessities.

Mark DeBoo’s steadfast dedication to preserving and enhancing the classic traits that built the Angus breed has made Diamond D Angus a true legacy in the beef cattle world—and a natural fit among Bos Sires Legacy Breeders.