With the growth of the ethanol industry, livestock producers will have an increasing quantity of distillers’ dried grains (DDGS) available as an alternative feed to provide protein and energy. However, DDGS will vary in its nutritional content from plant to plant, and pork producers are particularly urged to be knowledgeable of the characteristics of the DDGS before it is fed.

At the 2007 Midwest Swine Production Conference, University of Illinois swine nutrition specialist Hans Stein said, “Some DDGS products have been heated to an extent that the concentration and the digestibility of lysine has been reduced and it is, therefore, important that the concentration of lysine is measured in DDGS before it is used.” Stein’s presentation on Feeding DDGS to Pigs suggests that many new products from the ethanol industry will become available in the future and the feed value will need to be measured.

DDGS consists of the entire corn kernel, except the starch, which was removed and fermented for ethanol. Most of the earlier constructed ethanol plants were built only to remove the starch, but some of the newer processes will convert the corn kernel into different fractions that will result in a variety of products with different contents. Those might include products with varying quantities of hulls and germs. Stein says when the degermed and dehulled corn has been fermented, a high protein, low fat, low fiber product is produced, but the solubles stay with the hulls, and the remaining high protein product is 40% crude protein and is just DDG, distillers’ dried grain (no solubles). He recommends the inclusion of a 20% high protein DDG in diets fed to pigs, but if a 40% formulation is used, feed intake may be reduced in the growing period.

Other products from the ethanol plants may have had the corn oil removed, and the resulting product is only 4 to 6% crude fat, instead of 9 to 10%. Although untested, Stein expects the energy value is lowered 10 to 15% and less valuable than conventional DDGS. Another product may have had more fiber removed, which is also too new for feeding trials.

One of the prime considerations for a DDGS product is Lysine quality, quantity, and digestibility. Stein says there is more variability in Lysine digestibility than other amino acids because of heat damage during the drying process. Some DDGS samples with the lowest concentrations have the least digestibility. That is why lysine concentration needs to be quantified. Certainly lysine can be computed from the quantity of crude protein present, but because the processing can impact the lysine and not the crude protein, just knowing the crude protein is not sufficient. Stein says a color chart is not a good indicator of lysine, since the color of the DDGS can vary from time to time at an individual ethanol plant. Stein says part of the damage to the lysine comes when the solubles are reintroduced to the distillers’ grains, therefore he says DDG may be expected to have more lysine and it is more digestible than in DDGS.

Most of the available DDGS comes from ethanol plants producing a motor fuel, but Stein says there will be beverage ethanol plants that also produce DDGS. While no testing on the differences in nutritional characteristics has been done, Stein does not expect much difference in the quality and quantity of lysine. It all depends on the production process at an individual plant and the temperature during drying of the DDGS product.

Another difference of DDGS from various ethanol refineries is the concentration of phosphorus, and Stein says while the total amount of P is relatively small, there seems to be a wide variation in the amount of available P. Subsequently, it is important to establish the phosphorus content and the manner in which it was calculated.

In the end, the variations in characteristics of DDGS could be a substantial reason for the great variance in feed efficiency with different formulations of DDGS in swine rations. DDGS with a low lysine content will have an impact on finishing pig performance, and Stein says the crude protein concentration may also have been the limiting factor, “If the inclusion of crystalline
Amino acid is not increased, then the concentration of crude protein in the DDGS containing diets will increase. This can result in reduced feed intake, reduced dressing percentage, and reduced intestinal health, which in turn will reduce pig performance.” Until more research is done, Stein recommends not increasing the crude protein in a ration formulated with DDGS.

The end product is the meat quality of the animal, and Stein says the inclusion of DDGS in a diet fed to finishing pigs does not influence the palatability of bacon or pork chops. However, DDGS fed to finishing pigs will increase the iodine values and produce softer bellies than conventional rations, but the reasons are unknown.

Summary:
More ethanol plants mean more distillers’ dried grains available for livestock feed, but it also means more variability in the nutritional content, particularly in the quantity and digestibility of lysine which is important for swine rations. The variability results from the processing, which is different at individual plants, and pork producers should have DDGS analyzed to ensure quality and help quantify the value of the product being purchased for hog feed.