David Trowbridge has always had a love for animals, specifically cattle. He wanted to return to the family’s dairy farm in Nebraska after earning an animal science degree from the University of Nebraska at Lincoln, but there wasn’t room. His four brothers were a part of the farm, and his dad didn’t think the 200-head dairy farm was large enough to support another family.

So he and his wife, Mary, found opportunities in Tabor, Iowa.

Forty-two years later, David is still manager of a family-owned custom feedlot, Gregory...