The polio problem comes from excess sulfur in the DDGS.  If it's feed at too high of concentration this will cause problems.  Cows can only handle 0.4% sulfur.  DDGS can be between 0.5 to 1.0%, maybe more.  Fortunately, corn is about 0.10-0.15%, so it "dilutes" the sulfur, along with the hay you might feed.

One thing that helps the polio problem is to feed a balancer mineral that contains thiamine.  Having this in the mix tends to reduce polio problems.