Jeffress was banned for 50 games in 2007 and 100 games last year for his repeat violation. The 22-year-old joined the team in Cincinnati on Wednesday, ready for his major league debut. Jeffress went 1-1 with three saves in 11 appearances at Double-A Huntsville.
The Brewers also called up right-hander Carlos Villanueva and third baseman Mat Gamel on Wednesday. Villanueva was optioned to Triple-A Nashville on July 28. Gamel batted .309 with 13 homers in 82 games at Nashville after missing two months with a torn muscle in his right shoulder.