Rangers' Derek Holland on DL

OAKLAND, Calif. -- The Texas Rangers placed left-handed starting pitcher Derek Holland on the 15-day disabled list with left shoulder fatigue and will move Alexi Ogando from the bullpen to the rotation to take Holland's spot.

Right-handed reliever Tanner Scheppers was called up from Triple-A Round Rock to take Holland's place on the roster and was available out of the bullpen for Thursday afternoon's 7-1 loss in Oakland. Scheppers pitched 1 2/3 innings and gave up a run.

Holland said Wednesday that he's lost 15 pounds in the last 2½ weeks because of a stomach ailment and his velocity dropped some late in Tuesday's start as the A's started to hit him harder in his final few innings.

Ogando, an All-Star selection last season, started 29 games in 2011 and had a 13-8 record and a 3.51 ERA.

"The transition (to starter) is not a big deal," he said through an interpreter. "It's just getting an opportunity to come in and start, which is something I like to do."

When asked how long he thought he could go, Ogando replied: "I don't really know. It just depends on how much my stamina can keep me in there," conceding that 60 to 70 pitches sounded reasonable.

Manager Ron Washington wasn't as sure as Ogando, saying he "certainly" wouldn't be giving the pitcher a number.

"We'll see how far he can take us. We'll know more after his first time out there and we'll know more how far we can push him next time he takes the ball," Washington said. "If he pounds the strike zone and makes them swing the bat and gets some quick outs and gets us through five we'll be happy."

Holland is the second Rangers' starter to be placed on the disabled list in the past few weeks.

Neftali Feliz has a sprained ligament in his throwing elbow and could be out until the All-Star break. The Rangers, losers of six of their last eight games going into Thursday's action, have also seen Scott Feldman struggle as Feliz's replacement. But Feldman's spot likely will go to Roy Oswalt, who is still building up innings in the minors. He's slated to pitch Thursday for Round Rock and should be ready to join the rotation around June 20.

"I lost a good bit of weight," Holland told reporters Wednesday. "Of course I am concerned."

Holland said that he had been on an antibiotic and was feeling a little better.

"I just want to be able to get rid of it so I can be myself," said Holland, who is 5-4 with a 5.10 ERA in 12 games (11 starts) this season, just months after signing a long-term contract extension. "I want to be out there and have my team not be worried about how I feel."

Washington wasn't sure if Holland's weakness was from the virus.

"I really don't know," he said. "We want him full strength. We sent him back and get an evaluation and then move forward from there."

Washington said Holland would be evaluated orthopedically and internally.

Scheppers, 25, was the club's first-round (44th overall) pick in the 2009 draft and has pitched as a non-roster invitee in spring training the last three years. He is 1-2 with nine saves (in 12 chances) and a 3.72 ERA in 25 relief appearances for Round Rock this season. Scheppers, who will be looking to make his major league debut, pitched on Tuesday vs. Albuquerque and allowed a run in two innings.

To make room for Scheppers on the 40-man roster, the club designated left-handed pitcher John Gaub for assignment. Gaub was picked up on a waiver claim from the Tampa Bay Rays on May 24 and had thrown 4 1/3 scoreless innings in five appearances for Round Rock. Texas has 10 days to trade, release or outright Gaub to the minors.