Impact of Oil Extraction on the Nutritional Value of DDGS

Distiller’s Dried Grains with Solubles (DDGS) is a by-product of the distillery industries and is the dried product remaining after grain (mainly corn) is fermented with yeasts and enzymes to convert starch to alcohol. More than 95% of the DDGS in the U.S. comes from plants producing ethanol for fuel and the remaining comes from beverage alcohol plants.

The use of DDGS from modern ethanol plants in poultry and swine diets offers producers an opportunity to reduce diet costs, maintain animal performance, and improve profitability. DDGS is the most commonly fed byproduct from ethanol production fed to poultry and swine. From a nutritional standpoint, the energy value of DDGS is the same as corn even though almost all of the starch has been removed. This is because DDGS contains approximately three times the level of fat (~10%) as corn (~3.5% fat). This increased concentration of oil offsets the removal of starch on an energy basis.

Recently, dry-mill ethanol plants (plants supplying DDGS) have started to extract a portion of the oil from DDGS. Approximately, 50% of the ethanol plants in the U.S. are currently extracting oil. By the end of 2012, it is estimated that nearly 80% of ethanol plants will be extracting oil to some degree. The oil is removed from the condensed distillers solubles or stillage, which is the product left after ethanol has been removed. The extraction is a mechanical process utilizing centrifuges to remove the oil. Ethanol plants invest approximately $3 million to be able to extract oil but are able to pay back the investment in a matter of months due to current high prices received for selling corn (vegetable) oil.

Recently, dry-mill ethanol plants (plants supplying DDGS) have started to extract a portion of the oil from DDGS.

A majority of the corn oil being extracted is being used in biodiesel production. With the large amount of oil being extracted, there is a potential to use corn oil in animal feeds. This provides producers using all-vegetable diets an alternative vegetable oil to meet the energy needs of animals.

What influence does the removal of a portion of the oil have on the nutritional value of DDGS? Research conducted by POET nutritionists with poultry suggests that energy is reduced around 45 kcal/lb for every percent oil removed from DDGS. If 2% of oil is removed from DDGS, this results in an approximately 90 kcal/lb less energy in the resulting DDGS product.

However, swine researchers at the University of Minnesota and at USDA-ARS in Ames, Iowa suggest an adjustment in energy level based strictly on the amount of oil removed underestimates the energy reduction in DDGS. This is because the energy value of DDGS is influenced by both the fat and fiber level in DDGS. As fat is extracted from DDGS, the concentration of fiber is increased. Initial equations are now available for nutritionists to predict the energy of DDGS based on fiber and fat components in DDGS.

Table 1 shows a comparison of the nutrient profile of low and high fat Dakota Gold DDGS as analyzed by nutritionists at POET. The high fat DDGS contained 10.48% fat, and the low fat DDGS had 5.49% fat. The crude fiber content of the low fat DDGS was more concentrated as discussed earlier. However, the crude protein content of the low fat DDGS was increased. The concentration of critical amino acids like methionine, cystine, and lysine were similar between the two sources of DDGS. These differences in nutrient content need to be accounted for, in addition to the change in energy, when evaluating the overall nutritional value of partially de-oiled DDGS.

On the positive side for swine, partially de-oiled DDGS would be expected to have less of a negative impact on carcass quality since de-oiled DDGS would have less unsaturated fat. If producers have fed lower levels of DDGS or removed DDGS from diets prior to marketing, because of known or perceived problems with “soft” carcasses, de-oiled DDGS may allow producers to use DDGS in feeds all of the way to marketing.

The bottom-line with the changes in nutrient content of partially de-oiled DDGS is to determine the effect of utilizing DDGS in poultry and swine feeds. To evaluate economical value, the two sources of DDGS in Table 1 were compared in a representative peak layer, broiler finisher, and swine finisher feeds. The energy value for the two different DDGS sources was based on equations from POET nutritionists for poultry and from 2012 University of Minnesota and USDA/ARS research for swine.

The results of the economic analysis are shown in Table 2. The first column is the cost of the feed when no DDGS is allowed in the diet. The second column is the cost of the feed when either the Low Fat or High Fat DDGS is allowed in the diet (200 lb/ton maximum in the layer and broiler diets and 400 lb/ton maximum in the swine diet). The third column is the feed price difference.

All feeds used the maximum amount of DDGS (defined above) regardless of DDGS type. The addition of either low fat or high fat DDGS reduced feed cost. However, the use of the high fat DDGS saved over $4 more per ton in the layer and broiler feeds and over $8 more per ton in the swine feed than using low fat DDGS.

The partial removal of oil from DDGS has a significant effect on energy value of DDGS. The energy level of DDGS is reduced not only as a result of the extraction of oil but also due to a concentration of the fiber components in DDGS. These changes in nutritional value significantly impact the economic value of using DDGS in poultry and swine feeds. In the examples shared, the use of Low Fat or High Fat DDGS still helped to reduce feed cost, but greater savings were realized using High Fat DDGS. As more ethanol plants extract at least a portion of the oil from DDGS, Wenger Feeds will be monitoring price and critically evaluating the payback from utilizing de-oiled DDGS.

For more information about Wenger Feeds’ Products and Services, contact us.