Ask most Iowa beef producers if they keep their cattle on feed for two years, and they’ll laugh. Ask Brad and Shawna Feddersen, and they’ll nod yes and offer a tour of their feedyards in the hills of Woodbury County, where they raise Wagyu beef cattle.

“The goal of feeding this long is to produce exceptional marbling in the meat,” said Brad Feddersen, who farms near Anthon in northwest Iowa.

There are no shortcuts to producing Wagyu, a Japanese cattle breed known for its superior meat quality. Wagyu cattle are descended from...