Barton went on the DL because of a strained right shoulder that limited him to seven games this spring. He played in four straight games for Triple-A Sacramento, hitting a grand slam Sunday at Las Vegas, and was in the lineup Monday night for the opener of a three-game home series with Kansas City.
To make roster room for Barton, the A's designated first baseman Brandon Allen for assignment.
Barton says he doesn't feel any pain in the shoulder while hitting but experiences some tightness when he throws and will be cautious. Manager Bob Melvin will sit Barton when he needs a break.