Aaron Rodgers Cuts the Cheese ... Wisconsin Congressman is APPALLED!!!

News that Aaron Rodgers is axing dairy -- INCLUDING CHEESE!!! -- didn't sit well with Wisconsin congressman Sean Duffy.

We caught the U.S. Rep walking around in D.C. when we clued him in on the Packers QB's new diet plan. Check out the vid ... Sean couldn't believe his ears when we told him the NFL superstar's eliminating dairy. Y'a know ... cause milk/cheese = protein.

Rodgers told ESPN he wants to follow a stricter eating regimen following knee surgery in January ... sparking a near MELTDOWN among faithful cheeseheads.