Distillers grains are by-products of when grains are fermented into alcohol. The spent grains are dried and sold as feed. Solubles left over from fermentation usually are added to the distillers grains (DDG) before drying, resulting in a product called distillers dried grains with solubles (DDGS), the most common commercial product. Distillers grains are identified by the type of grain from which they are made, i.e. corn distillers, milo distillers, or other grains (wheat or rye). Distillers Dried Grains with solubles (DDGS) is the product obtained by condensing and drying the stillage that remains after fermenting the starch in corn or milo in the production of ethyl alcohol.

There is renewed interest in feeding DDGS to swine because the rapid growth of the ethanol industry in the Midwest has increased the quantity and local supply. Historically, DDGS has not been used in swine diets because of the low protein quality (poor amino acid balance), low amino acid digestibility, high fiber content and the nutrient variability among sources. This left an image of an inferior ingredient for swine diets. Today, according to University of Minnesota research the new ethanol plants are producing DDGS with higher nutrient content and digestibility than that listed in the 1998 National Research Council publication on Nutrient Requirements of Swine.

Nutrient Profile

When compared to corn, the typical energy source used in Midwestern swine diets, the nutrient profile of DDGS varies slightly. Distillers' grains has higher protein (25 to 30%), fat (8 to 10%), and fiber (4 to 12%) content than corn due to the fermentation process removing the starch component. Distillers' by-products do have several features that limit their use in swine diets. The high fiber content may cause diarrhea in young pigs. Distillers' grains will have a lower metabolizable energy content due to less starch. The crude protein content is relatively high, but the amino acid profile is not well balanced. For example, distillers' grains are quite low in lysine content (0.6 to 0.9%). Therefore, swine diets containing distillers' dried grain with solubles (DDGS) need to be formulated on a digestible lysine and energy basis. Formulating the diet on a crude protein basis will result in a lysine deficiency and possible a deficiency of other amino acids, such as tryptophan, methionine or threonine, which will reduce growth performance.

Growth Performance

DDGS can be used in nursery, growing-finishing (G-F), gestation and lactation diets. Several research studies have reported favorable results in growth and feed efficiency of pig when fed 2.5 to 5% of DDGS. The maximum recommended inclusion rate of DDGS in 35 to 250 pound pig diets is 20%. The more acceptable inclusion rate is 10% in G-F diets. When the 20% inclusion rate is used then synthetic lysine and tryptophan should be added to maintain an amino acid balanced diet with adequate growth performance.

Recommended Maximum Inclusion Rates of DDGS in Swine Diets

Based upon research studies conducted at the University of Minnesota over the last three years, the recommended maximum usage rate of DDGS in swine diets are as follows (Assuming that high quality DDGS is free of mycotoxins):

Table 1 gives a comparison of nutrient content, apparent amino acid digestibility, and phosphorus availability of MN/SD DDGS, a low quality DDGS source, and NRC (1998).

Table 1. Comparison of Nutrient Content, Apparent Amino Acid Digestibility, and Phosphorus Availability of MN/SD DDGS, a Low Quality DDGS Source, and NRC (1998)^a

^aSource: Feeding recommendations and Example Diets Containing MN/SD Produced DDGS for Swine. Jerry Shurson and Mindy Speihs, Department of Animal Science, University of Minnesota.

Cautions in Feeding DDGS to Swine

1. Quality
   1. There is a large variation in the quality of DDGS available for swine feeds. Golden color DDGS is much better suited for swine diets than darker colored DDGS due to higher amino acid digestibility.
   2. Odor ranges from sweet to smoky to burnt
   3. According to research at the University of Minnesota, DDGS produced by new Midwestern plants is higher in nutrient content and digestibility (Table 1) than DDGS from older plants.
   4. Quality considerations for selecting DDGS sources:
      • Nutrient Specifications
        • Moisture - maximum 12%
        • Protein - minimum 26.5%
        • Fat - minimum 10%
        • Fiber - maximum 7.5%
2. Nutrient variability of Midwestern DDGS sources
   1. a. Dry matter - 87 to 93%
   2. b. Crude protein - 23 to 29%
   3. c. Crude fat - 3 to 12%
   4. d. Ash - 3 to 6%
   5. e. Lysine - 0.59 to 0.89%
3. Pork fat quality

   University of Minnesota studies have shown that when feeding DDGS to G-F pigs (50-250 lbs), the oil present in DDGS will make pork carcass fat softer and more oily with increasing levels of DDGS in the diet.These same studies showed that feeding up to 20% DDGS in G-F pig diets had not effect on belly thickness or belly firmness score compared to carcasses from G-F pigs fed conventional corn-soybean meal diets.

4. Mycotoxins

   Corn is susceptible to molds that can produce mycotoxins prior to harvest, as well as during storage. The primary mycotoxins of concern to swine are zearalenone, vomitoxin (deoxynivalenol), T-2 toxin, fumonisin, and aflatoxins. In the Midwestern U.S., zearalenone and vomitoxin are the greatest risk.

5. Amino acid digestibility is reduced in dark colored DDGS.
6. High fiber limits its use in pre-starter diets (< 15 lb liveweight)
7. Because of the high fiber content, sows will take twice as long to eat their daily feed allotment than sows fed a corn-soybean meal diet.

Maximizing the Value of DDGS in Swine Diets

1. Excess nitrogen can be minimized by using synthetic amino acids.
2. Dietary inclusion rates should be gradually increased in gestation (up to 40%) and lactation (up to 20%) diets to allow sows to adapt.
3. 3.Formulate diets using digestible amino acid values.
4. High available phosphorus reduces the level of dietary phosphorus supplementation.

Feeding Recommendations

For feeding recommendations and example diets containing DDGS for all classes of swine, contact Dr. Gilbert Hollis, 1207 West Gregory Drive, Urbana, IL61801; E-mail: g-hollis@uiuc.edu or see the following University of Minnesota web site: www.ddgs.umn.edu/info-swine.htm