Hirsh (1-1) gave up three hits, walked four and struck out five in his second big-league start.
"The guys took care of me earlier, congratulated me," Hirsh said afterward.
"Like they were saying, only 299 more to go. We'll just take it one game at a time and see where it goes from here," he said.
Houston scored three runs off Sheets (3-5) in the fifth to take a 5-2 lead. Willy Taveras singled with one out and Craig Biggio was hit by a pitch for the 281st time in his career, extending his major-league record. Mike Lamb singled in Taveras and Luke Scott
added a two-out, two-run triple to center.
"I was absolutely pathetic," Sheets said. "There was just nothing good about it. Nothing was good. I think every pitch got hit hard."
Huff hit a sacrifice fly in the second and a solo homer in the fourth, his fifth with the Astros and 13th overall this season. Berkman's two-run drive in the seventh, his 33rd of the year, made it 7-3.
Milwaukee, which managed only five hits, came within 5-3 in the sixth when reliever Chad Qualls walked David Bell with the bases loaded. But Damian Miller then grounded into an inning-ending double play.
"You're hoping someone gets a big hit," Milwaukee manager Ned Yost said. "He threw a tough pitch to Miller. He threw a two-seamer in on his hands and got him."
Taveras also reached on a bunt single in the third to extend his hitting streak to 20 games.
Houston manager Phil Garner said it's important for players besides Berkman to hit well if the Astros are to stay in the NL wild-card race, where they trail Cincinnati by four games.
"If those guys swing the bat like that, and Aubrey swings the ball like that, then people have to think twice about pitching around Lance," he said. "That very well may have led to Lance hitting the home run later."
Sheets, who missed nearly three months with tendinitis in his right shoulder, pitched seven innings, giving up seven runs and 10 hits with four walks and five strikeouts. He said the velocity was down on his fastball.
"I don't know why," he said. "I feel too good to be throwing that slow. I shouldn't rear back and throw a fastball and it be 88 mph. I think that's the leading factor as to why the breaking ball was not good. When my arm speed is up, my breaking ball is pretty
It was the most runs given up by Sheets since he allowed seven in 2 1/3 innings against Houston on May 2, his last start before going on the disabled list. His ERA rose from 4.98 to 5.54.
Hirsh, the Astros' second-round draft pick in 2003, was 13-2 at Triple-A Round Rock before being recalled to Houston on Aug. 12. In his first start against San Diego on Aug. 12, the 6-foot-8, 250-pound right-hander gave up four runs in four innings.
Corey Hart, batting leadoff for the first time in his career, homered in the first for Milwaukee.
Taveras' hitting streak is tied for the fifth longest this year with Atlanta's Chipper Jones and Seattle's Ichiro Suzuki. ... Brewers right fielder Geoff Jenkins started for the first time since being told by Yost on Aug. 11 that he would come off the bench for much of the final weeks of the season. ... Sheets has given up 12 runs in 14 innings over his last two starts. ... Garner appeared to speak harshly to Scott in the fourth after he failed to run hard to first on a strikeout that was dropped. He was out by a step and Huff followed with a home run.