Corn gluten feed is a byproduct of the corn syrup and corn starch manufacturing process. Much different than DDG which is byproduct of ethanol manufacturing (use to be primarily from high quality whiskey distilling. lol). DDG is a much higher quality product ranging in crude protein from 25% to as much as 34% and containing fat levels as high as 15% in some cases. Corn gluten feed will vary from 14% crude protein up to as high s 21% in some instances but most of the fat has been removed thus it has much lower net energy values than DDG and is considered more as a simply grain by-product. Just a personal opinion but I have very high regard for DDG but Corn gluten always hits me as sort of a "last resort" feed ingredient. Both work well when used properly and can be very cost effective.