It all depends on what type of cattle you are talking about.
Beef cattle fed on grass tend to be more tough,because they don't have marble in the meat from eating corn products.
Dairy cattle fed grass without a corn or grain supplement will not produce as much milk.That is why you see beef cattle in a feed yard and milk cows confined to a dairy setting.
As far as risks are concerned feeding corn to livestock,is no different then me eating corn off the stock.
Mostly a big myth created by people who are vegetarians.
Any time you buy beef in the store it will most likely be corn or grain fed.
Any time you buy milk in the store it will most likely be from dairy cattle fed grain,corn or silage.