The Giants activated a pair of right-handed pitchers who they hoped would be able to provide bulk innings in Wednesday night’s series finale against the Astros.

Trevor Cahill and Dereck Rodríguez were added to the 28-man roster for the first time this season, taking the spots of rookie relievers Conner Menez and Rico Garcia, who were both optioned to the club’s alternate training site in Sacramento.

The Giants designated Andrew Triggs for assignment to clear a spot on the 40-man roster for Cahill, who started against the Astros on Wednesday in place of the injured Jeff Samardzija. Triggs struggled in his lone appearance for San Francisco this year, allowing three runs in one-third of an inning against the Rangers last week.

Cahill missed the first few weeks of the regular season with a fingernail injury and was only built up to throw 45-50 pitches, so the Giants recalled Rodríguez to serve as a potential long man out of the bullpen. Cahill threw 55 pitches while walking four and allowing no hits in 1 1/3 shutout innings of Wednesday's 5-1 loss.

“It’s nice to have some length on the roster tonight given the fact that Cahill is not especially stretched out,” manager Gabe Kapler said before Wednesday's game. “We know we’re going to need to cover innings today. We needed some length.”

After Shaun Anderson got the final out of the second inning, Rodríguez contributed 2 1/3 innings, allowing one run on three hits and two walks. Four other relievers combined for the remaining 3 2/3 frames.

Rodríguez was added to the Giants’ taxi squad at the beginning of their 10-game road trip and impressed the club during his two most recent bullpen sessions. Kapler said Rodríguez showed an uptick in velocity, with his fastball reaching 92-94 mph. The 28-year-old averaged 90.7 mph on his fastball last year, down from 91.6 in 2018, but he credited assistant pitching coach Ethan Katz with helping him make adjustments that enabled him to recoup some of that velocity.

“Katzy helped me out a lot and shortened up my arm a little bit,” Rodríguez said. “I think that’s what helped me bring the velo back out.”

Garcia has had a couple of rough outings recently that caused his ERA to spike to 7.50 on the season, but Menez has been an effective option out of the bullpen for the Giants. He logged a 2.38 ERA over his first seven appearances of the season, but he likely would have been unavailable to pitch on Wednesday after throwing 2 2/3 innings behind Logan Webb on Monday.

“The message to Conner was there’s really not much you can be doing differently,” Kapler said. “You’re doing a great job. This is more about us getting an arm that can give us some length today. It’s not going to hurt him to have a little bit of a blow and come back even stronger.”

Worth noting

• Austin Slater was originally penciled in to start in right field and bat third against Astros right-hander Zack Greinke on Wednesday, but he was a late scratch from the lineup. No reason was given for the lineup change. Hunter Pence replaced Slater in right field, with Wilmer Flores starting at designated hitter.

• Donovan Solano was out of the lineup for the second consecutive game with abdominal soreness. Kapler said the Giants are hoping he’ll be ready to return following the club’s off-day on Thursday.

• Drew Smyly, who was placed on the injured list with a left index finger sprain, has resumed throwing changeups.

• Johnny Cueto, Kevin Gausman and Webb will start for the Giants in this weekend’s Bay Bridge series against the A’s in that order.