Sweet corn is what you buy in the grocery store by the ear or in the can/freezer bags.
Cow corn is what farmers grow to feed livestock. This is the type of corn also used for ethanol production.
So, diverting more corn production to use in ethanol makes feed corn more expensive. It probably has an effect on swine and cattle feed pricing.
It is not going to affect the price of milk.
They sell the mash for feed. Its a scam. That mash only has the sugars removed and it still has the proteins in it.
So what they are doing is using that corn liquor for gasoline additive and then getting the subsidy for it and still making the money selling the mash for stock feed.