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5/26/2013 2:07 P.M. ET

Porter to give Castro more starts as DH

HOUSTON -- Astros regular catcher Jason Castro is settling in to a new part-time position: designated hitter. Castro was the DH on Sunday against the A's, and Houston manager Bo Porter said that the role could be a more common sight as he tries to protect Castro's health.

Castro tore an ACL and a meniscus in his right knee during Spring Training in 2011, missing that entire season as a result. He also missed time last year with soreness in the same leg.

Sunday marked Castro's fifth time at the DH spot this season. He was just 1-for-16 with one RBI in his first four starts as designated hitter. Porter said he made a promise to Castro in Spring Training to keep him healthy and allow him to catch as many games as possible.

"Some days that means he'll DH, because I want to give him that rest and still keep his bat in the lineup," Porter said. "That's one of the advantages of being in the American League, moving the DH around. Catching is the most difficult position to play every day at the Major League level. It's taxing to the body to get back there and squat all night. It's taxing mentally, too, because you have to know your own pitchers, call a game and respond to each batters' tendencies. You need a break sometimes."

Castro said his surgically repaired knee has given him no problems this year, but he's comfortable with his duty as a spot starter at designated hitter.

The former 2008 first-round Draft pick leads the team with 13 doubles and hit two home runs against Oakland on Saturday night.

Dominguez showing he can be a force in lineup

HOUSTON -- As the temperature outside Minute Maid Park starts to hit 90 degrees or more for the rest of the summer, Astros third baseman Matt Dominguez's bat is heating up inside the ballpark.

Dominguez has launched seven home runs and compiled 12 RBIs in his last 13 games, showing pop at the plate to go along with his consistently terrific defensive play.

"He's got great pull power and great carry to the pull and his bat stays in the zone long enough where he can also drive the ball out of the park the other way," said Astros manager Bo Porter. "Overall, his development has been outstanding. Coming into the season, we knew what we had defensively and we're now we're starting to see the power display itself. I always go back to the fact he's established himself as a complete hitter, and he understands he has to use the whole field."

The 23-year-old hit five homers in 31 games in 2012, but hadn't hit a homer through his first 122 at-bats this season. Then, a two-homer day against Yu Darvish and the Rangers on May 11 sparked his bat. He hit two home runs again on Saturday night against the A's, both solo shots.

Dominguez said he's been taking batting practice "with a purpose" and heeding Porter's advice to work counts.

"If you're patient and working the pitcher, you get those pitches you want," he said. "I try to pull the ball only when I've set the pitcher up to give me a ball inside."

He's done all of this while dealing with a sore left quadriceps, which he hurt in the batting cage several weeks ago and caused him to miss the Royals game on May 22. Dominguez said he's constantly receiving treatment on the injury, but the two days of rest (the Astros were off on May 23) "helped loosen it up."

Astros wives and girlfriends help tornado victims

HOUSTON -- More than a dozen wives and girlfriends of Astros players raised $9,000 dollars at Minute Maid Park on Sunday afternoon by selling mystery bags containing autographed baseballs. One-hundred percent of the money collected will go to the Red Cross to help with Oklahoma tornado relief.

Last week's tornado that ripped through Moore, Okla., hit close to home for the Astros, whose Triple-A team is in Oklahoma City. Many of the players on the team and their wives have spent considerable time in Oklahoma City in recent years.

"It's great to support the community," said Maris Castro, wife of Astros catcher Jason Castro. "We have our Triple-A team in Oklahoma City, so it's great to be able to help a community that's related to the Astros. When you see people lose their homes and everything that they own and hold dear to themselves and see people lose their lives, you do whatever you can to help people."

Among the wives selling bags at five different gates on Sunday were Shawn Barnes, Stephanie Corporan, Loren Maxwell, Gina Luhnow, Sherell Wright, Marlee Clemens, Stephanie Ambriz, Noel Gonzalez, Pamela Pena, Gissele Veras, Stacey Porter and Nina Altuve. The girlfriends who helped raised money were Aubree Gerardi, Jenna Cecil and Brittany Stemwedel.

"It's been amazing," Pena said. "We got here and had people waiting for us. We sold 20 bags in five minutes, so it was awesome."

Castro said the players have been more than willing to help.

"They all want to do what they can," she said. "It's hard when you're working every day to really get involved, so this is what they can do to help out."

Meanwhile, the Astros Foundation is raising funds for the Red Cross during the current homestand with a "Jeresys Off Their Backs" silent auction. Game-worn jerseys are being auctioned on the main concourse along the third-base line.

Brian McTaggart is a reporter for MLB.com and writes an MLBlog, . Chris Abshire is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.