Yoshinoya D&C Co. is testing "butadon" pork-on-rice dishes at some of its restaurants after a ban on U.S. beef imports forced the firm to suspend its mainstay dish of "gyudon" beef and rice earlier this month.

Company sources said Wednesday the chain might introduce butadon as a regular menu item in March depending on how customers take to the new dish.

Other gyudon restaurant chains, including Nakau Co. and Zensho Co., are already offering butadon.

The import ban followed the discovery of mad cow disease in the U.S.