Nutritional characteristics of corn distillers dried grains with solubles as affected by the amounts of grains versus solubles and different processing techniques

Experiments were conducted to evaluate the nutritional value of corn distillers dried grains with solubles (DDGS) and its components of grains and solubles, the effect on amino acid digestibility of autoclaving DDGS with different proportions of wet grains:solubles, and the effect of several new processing technologies on the nutritional value of DDGS for poultry. In the latter experiments, corn was processed under laboratory conditions to produce ethanol and DDGS by using the conventional dry-grind process and compared with 2 modified dry-grind corn processes. Modified dry-grind corn processes consisted of wet quick germ, quick fiber (QGQF process) and dry degerm defiber (3D process) fractionation of corn to recover the germ and pericarp fiber prior to fermentation. In another process, a commercial DDGS sample was subjected to an Elusieve method to remove fiber and increase the protein content. Freeze-dried solubles were higher in total P but lower in CP than in the grains and DDGS. Digestibilities of several amino acids in the freeze-dried grains and solubles were higher than those for DDGS, particularly for Lys. Autoclaving reduced the digestibility of amino acids in DDGS, and this effect was not influenced by the proportion of grains:solubles. The QGQF and 3D processes increased the protein and reduced the fat and total dietary fiber content in DDGS. Total P was increased by the QGQF process, but was reduced by the 3D process. The Elusieve process increased the protein, amino acids, and fat, and decreased the total dietary fiber content of DDGS from 34.5 to 19.7% on a DM basis. None of the processing technologies had a significant effect on DDGS amino acid digestibility. The results of this study indicated that the nutritional value of DDGS can be influenced greatly by the proportion of grains vs. solubles and by processing technologies.