Herring is out four to six weeks after right knee surgery, and Watt will miss about two months after surgery on his right foot.
Both Herring and Watt sustained their injuries during last Saturday's loss to LSU.
Herring, who has played in 36 career games, could return for Wisconsin's Big Ten opener Oct. 4 at Northwestern. Watt has started five games in each of the past two seasons.
Starting defensive end Konrad Zagzebski, who was carted off the field against LSU after sustaining a blow to the head, is practicing this week and could play Saturday against Western Illinois.
Zagzebski told reporters he temporarily lost feeling on his left side after the hit and was taken to the hospital as a precaution. He underwent tests and was cleared to return to practice.