The moves leave the Astros with 44 players in camp -- 21 pitchers, four catchers, 11 infielders and eight outfielders.
"We wanted to make sure for the final two weeks that guys we know aren't going to be on the big league club, they start to work with their respective teams -- pitching coaches, hitting coaches, etc. -- so there might be a few more of these coming in the next few days," general manager Jeff Luhnow said.
Lo, who appeared in 19 games for the Astros last season, was competing for one of the spots in the bullpen and appeared in four games this spring, allowing one earned run in 3 1/3 innings. He will likely start the season at Triple-A Oklahoma City, which would mark his first time at that level.
"It will be good for him," Luhnow said. "There are still some things specifically he needs to work on. He got those instructions today and made sure he understood it, and he'll go execute it and get the innings down there. It's tough for us to get everybody innings up here, and now at least for the next couple of weeks, they'll be able to get plenty of innings to get ready for the season."
Cruz, a former Rule 5 Draft pick who spent most of last season at Triple-A, threw only 2 2/3 innings this spring and gave up three earned runs and walked one.
"[They told me to] just go down there and keep working hard the same way we've been doing in Spring Training," he said. "Just go down there and still throw my fastball and my slider in any count. That's all I'm going to do down there -- work hard and try to go out there again."
De Leon actually pitched well this spring after being slowed by a quad injury. He appeared in five games and gave up four hits and one run in five innings.
"They told me I've done a good job," he said. "They told me my stuff -- my slider, changeup, split -- improved. They told me to keep working, and if they need me, they're going to call me."
Owens, coming off a foot injury that cost him nearly the entire 2013 season, was a long shot to make the rotation and will likely be in the rotation at Oklahoma City. He appeared in three games this spring, making two starts, and was 0-1 with an 8.31 ERA.
Acquired from the Pirates in the Wandy Rodriguez deal in 2012, Owens missed most of last season because of a stress fracture in his left foot. He made four appearances (three starts), producing an 0-3 record and 3.71 ERA in 17 innings. He pitched in the Dominican Winter League, producing a 3-2 record and 2.68 ERA in 10 starts and 53 2/3 innings.
"Last year, when he got hurt and needed surgery, he was literally at the top of our list as the next guy to be called up," Luhnow said. "He knows how many pitchers we went through in Houston last year (25), and the message to him was, 'You put yourself back in that position and go down to Oklahoma City and pitch well, and make sure you stay at the top of the list so when we need someone, which we ultimately will, you're the guy that gets talked about.'"
McHugh, claimed off waivers in December, appeared in three games this spring and allowed 12 hits and nine earned runs in 5 2/3 innings. He split last season between the Mets and Rockies and the Minor Leagues of both organizations.
Cisnero went 2-2 with a 4.12 ERA in 28 games in his Major League debut last year. He pitched in three games in Grapefruit League play, allowing three hits and one earned run in 2 1/3 innings. Heineman spent all of last season at Class A Advanced Lancaster, hitting .286 with 13 homers and 71 RBIs.
"We're fortunate we've got a pretty decent roster of prospect catchers," Luhnow said. "He's on the radar now. Our collective belief is he's going to be a catcher in the big leagues, and he'll go to [Double-A] Corpus Christi and be able to share the workload there."