Technical Abstract: Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30 and 40% distillers dried grains with solubles (DDGS) along with 5% whey were prepared with a net protein content adjusted to 28%. Other ingredients in the blends included soy flour, corn flour, fish meal, vitamin and mineral mix. These blends were extruded in a single screw extruder at 15, 20, and 25% (wet basis - wb) moisture content and at 130 and 160 rpm screw speeds. The durability and unit density of the extrudates were found to increase substantially by the addition of whey to the blends. Increasing the DDGS content from 20 to 40% resulted in a 6.5%, 8.0%, and 5.2% decrease in moisture content, water activity, and brightness, respectively, as well as an 8.5% and 4.2% increase in redness and yellowness, respectively, of the extrudates. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in a 15.4%, 4.1%, 19.9%, 22.6%, and 8.4% decrease in moisture content, water activity, brightness, redness, and yellowness, respectively, of the extrudates. Changing the screw speed had no significant effect on most of the properties of the extrudates studied in our experiments, except for durability, unit density, and moisture content. Additionally, we observed an increase in fiber content of 31.8% and an increase in fat content of 66.0%. We also observed a decrease of 7.3% in Nitrogen Free Extract in the extrudates when the DDGS content was increased from 20 to 40%. As demonstrated in this study, ingredient moisture content and screw speed are critical considerations when producing extrudates with ingredient blends containing DDGS.