Our results confirm that adding 30% DDGS to a corn based diet reduces flowability, and grinding DDGS to 308 µm further reduces flowability compared to 594 and 818 µm particle sizes. Adding 30% DDGS to a corn based diets decreases dry matter digestibility, which will result in an increase in fecal excretion and manure production. However, for each 25 micron decrease in DDGS particle size from 818 microns to 308 microns, the ME contribution of DDGS to the diet is increased by 13.7 kcal/kg DM. If it is economic and feasible to pellet DDGS diets, the concern about flowability is eliminated and the extra energy value from using finely ground DDGS can be realized. However, if pelleting is not a viable option, and diets must be manufactured and fed in meal form, flowability may be acceptable if the DDGS particle size is greater than 600 µm, and some of the improved ME value of DDGS from a reduced particle size can be obtained. Compared to the price (e.g. $330/ton) and energy value (e.g. 7,956 kcal/kg) of choice white grease as an energy source in
grower-finisher swine diets, the difference in economic value of increased ME content for DDGS with particle size of 308 µm compared to 818 µm would be approximately $25.50 per ton of DDGS. Based on our results, DDGS particle size does not affect protein and phosphorus digestibility, so there is no additional economic or feeding value due to particle size on these economically important nutrients.