Notice the key words common inclusion rate (20%). Let's see what 40% regular DDGS does in comparison to 40% de-oiled DDGS inclusion rates.
They'll see a difference in carcass quality with the de-oiled DDGS subjects having superior carcass quality characteristics over the stuff that hasn't been extracted.
DDGS are a concentrate. Extracting the oil aligns the oil content to a level that's naturally found in corn. Lower oil content allows for higher inclusion rates of high protein feed.
I like comparing it to eating a bunch of fried food as opposed to baked. How do you feel after that bucket of chicken wings?
Here's a similar study on swine...
DDGS With Too Much Corn Oil, Bad For Livestock
Too much oil/fat in the DDGS raises the iodine levels creating unwanted soft fat. Soft fat contributes to many problems. Higher levels of extracted DDGS can be fed to livestock. Hope this helps.
"One challenge associated with DDGS feeding relates to soft fat that occurs in pork carcasses when high levels of DDGS are included in the diet. Soft fat creates problems for processors when they slice bacon and for consumers that discriminate against pork products that have an oily or soft appearance. The soft fat results from the high levels of corn oil present in the DDGS."
I believe that higher levels of DDGS can be fed to animals when the oil's extracted. The lower fat, higher protein feed is more nutritious and easier to digest. The resulting meat is firm, it cooks better, and is less greasy. This makes it better for us to eat.