Japanese Black (Wagyu) cattle are characterized by an ability to consistently produce highly palatable, well-marbled beef. The Japanese utilize a unique management program which includes feeding the cattle a high roughage diet for extended periods of time, typically at least twice that of American feedlot practices. In this study, Angus steers were fed a typical US feedlot diet to the Japanese market endpoint of 680 kg. Carcasses were analyzed for marbling score, meat color and fat color by days on feed and adjusted to a common carcass weight. Results indicate that the quality traits studied did change (P < 0.05) with an increasing number of days on feed. The marbling score had a high standard error.