A series of tweets from @brianmctaggart around 5:30 pm Friday night announced that the Astros have released 17 members of their farm system. The tweets are fairly easy to find in McTaggart's feed if you want to know the 17 the players who won't be wearing the new uniforms.
Make that 18. According to McTaggart, Brad Propst, RHP, was released as well.
Make that 23. Per an update from Baseball America, Matt Downs, IF, Rodney Quintero, RHP, Gabriel Garcia, LHP, Kilby Pena, LHP, and JB Shuck, OF were also released by Houston. (Note the first 18 releases are also included in the Baseball America post.)