OAKLAND, Calif. » Oakland designated first baseman Kila Ka’aihue for assignment and promoted Brandon Moss from Triple-A Sacramento. Moss had an out clause in his contract if he wasn’t in the big leagues by June 15.

Ka’aihue’s wife is due with twins any day, and manager Bob Melvin called it "very tough" to let him go.

In other Athletics news, reliever Andrew Carignan is likely headed for elbow ligament replacement surgery after leaving Tuesday’s game against Texas in the eighth inning with a sore arm.

The A’s placed the right-hander on the 15-day disabled list Wednesday with a sprained ulnar collateral ligament and he is expected to undergo more tests.