For the past year, the nation's biggest grocer worked with meat giants including Tyson Foods Inc. and Cargill Inc. to secure a supply of Angus steaks and roasts at no additional cost to consumers, said Scott Neal, Wal-Mart's senior vice president of meat, seafood, and quality control. The higher-quality cuts have been available in all of Wal-Mart's 4,700 U.S. stores since March, but the retailer hasn't announced or advertised the shift yet.