Evaluating Distiller's Dried Grains with Solubles

The use of “new generation” distiller's dried grains with solubles (DDGS) in swine feeding programs is increasing dramatically.

New generation DDGS is a corn co-product produced by relatively new dry mill ethanol plants in the Midwest. It is nutritionally different from corn gluten feed and corn gluten meal produced by wet mill ethanol plants. This is an important distinction because some corn co-products are being marketed as DDGS — but they are really different corn co-products produced under different processing methods. For example, one product being marketed as DDGS is really corn gluten feed with some corn gluten meal added.

University of Minnesota research has shown that true DDGS is an excellent alternative feed ingredient for swine in all phases of production. It is also a good value compared to the cost of the feed ingredients it partially replaces in typical swine diets — corn, soybean meal and dicalcium phosphate. With a projected 66% increase in DDGS supply by 2005, supply will be plentiful throughout much of the Midwest.

Producers are most interested in the feed cost savings and other benefits DDGS offer. We'll focus on seven questions related to the economic value of DDGS in swine diets:

1. How does price of DDGS compare to corn, soybean meal and dicalcium phosphate?

   The price of DDGS, like all other feed ingredients, is determined by a variety of external factors that affect supply and demand. Commodity traders establish the market price based on protein and energy value. DDGS prices track corn and soybean meal prices fairly closely.

   Since DDGS has traditionally been used more in the dairy industry, it has been valued more for its by-pass protein content than its energy value. However, simply basing your decision on cost/lb. of protein when comparing the price of DDGS to other ingredients will undervalue its energy and phosphorus value and overvalue protein in swine feeds. Phosphorus is the third most expensive nutrient in swine diets.

   One of the main advantages of using DDGS in swine diets is its relatively high available phosphorus content (0.66%) compared to other grains and grain co-products. This high available phosphorus level enables nutritionists to use less supplemental inorganic phosphate (e.g. dicalcium phosphate) to reduce diet cost while meeting the pigs' phosphorus needs.

2. What's the energy value of your source of DDGS?

   The three nutrient categories of greatest economic importance in swine diets are energy, amino acids and phosphorus. Research at the University of Minnesota has shown that new generation DDGS has a high metabolizable energy (ME) value (1,527 kcal/lb.) that is comparable to corn (1,550 kcal/lb.). However, depending on the source, the energy value can be substantially lower.

   For example, in a recent University of Minnesota report, the calculated ME value of DDGS obtained from an “old generation” ethanol plant was 1,405 kcal ME/lb. (approximately 92% of the energy value of new generation DDGS). The National Research Council “Nutrient Requirements of Swine” 1998 publication lists the ME value of DDGS at 1,210 kcal/lb. (79% of the value obtained for new generation DDGS).

   By using high quality, new generation DDGS, virtually no additional supplemental fat is needed to maintain desired dietary energy levels in typical corn-soybean meal diets.

   Recent economic analysis at Kansas State University suggests grow-finish diets containing 15% new generation DDGS (1,527 kcal/lb.) could result in more than a $1/pig increase in margin over feed costs compared to traditional corn-soybean meal diets.

3. What are the total and digestible amino acid values of your DDGS source?

   The total amino acid levels, especially lysine, in DDGS are important for determining the economic value. The higher the lysine, the more soybean meal it can replace in the diet. Like all feed ingredients, the nutrient content of DDGS varies among sources. However, once you've identified your source and the nutrient profile, you can be relatively precise in your diet formulations.

   Lysine is the most variable amino acid in DDGS. In a recent University of Minnesota study, DDGS samples were obtained from 10 new generation ethanol plants and analyzed for nutrient content, including total lysine. The range in total lysine levels varied from 0.63% to 0.90% (average: 0.73%). It appears that much of the variation in total lysine content is related to the normal variation in lysine content of corn being delivered to plants.

   If we use the average lysine, methionine + cystine, threonine, and tryptophan values found in the Minnesota study, and calculate values that are 10% below and 10% above these average values, this range would be typical of the variability in amino acid values among new generation DDGS sources (Table 1).

   Using the nutrient values in Table 1, grower diets (0.85% total lysine) were formulated on a digestible amino acid and available phosphorus basis using 200 or 400 lb./ton of new generation DDGS. The composition and cost of these diets are shown in Table 2.

   Compared to a typical corn-soybean meal diet containing 3 lb. of synthetic lysine/ton, adding 200 lb. of DDGS/ton of complete feed will reduce diet cost by 19¢/ton. This cost savings is realized because adding 200 lb. of DDGS/ton will replace 177 lb. of corn, 19 lb. of soybean meal and 6.5 lb. of 18.5% P dicalcium phosphate using the ingredient prices listed. Doubling the amount of DDGS will double the cost savings.

   Table 3. Composition and Cost of Grower Diets Containing 10% DDGS and Formulated on Total Lysine and Phosphorus Basis or Digestible Lysine and Available Phosphorus Basis Compared to a Typical Corn-SBM Diet Containing 3 lb. of Synthetic Lysine.

   Ingredient	Corn-SBM +3 lb. Lysine	10% DDGS Formulated on a Total Lysine Basis	10% DDGS Formulated on a Digestible Lysine Basis
   Corn, lb.	1,463	1,301	1,286
   SBM 44%, lb.	482	446	463
   DDGS, lb.	0	200	200
   Dicalcium phosphate, lb.	24	19	17
   Limestone, lb.	14	17	17
   Salt, lb.	6	6	6
   L-lysine HCl, lb.	3	3	3
   VTM premix, lb.	8	8	8
   TOTAL	2,000	2,000	2,000
   Total Cost, $	109.80	108.40	109.18
   Difference $	-	-1.40	-0.62
   Feed ingredient prices used: corn = $2.00/bu, SBM 44% = $190/ton, DDGS = $85/ton, dicalcium phosphate = $15/cwt., L-lysine HCl = $1/lb., VTM = vitamin.

   Using this formulation approach, there is a 31¢/ton difference in diet cost savings when using a DDGS source high in lysine compared to the low lysine source at an inclusion rate of 200 lb./ton. The spread in DDGS value between the low and high lysine values used in this example is $3.10/ton of DDGS (low lysine, $83.40/ton vs. high lysine, $86.50).

4. Do you formulate diets on a total amino acid or a digestible amino acid basis?

   The method used to formulate DDGS diets will greatly affect its value in swine diets. Many nutritionists formulate corn-soybean meal-based diets to achieve a desired level of total lysine and total phosphorus. Using this approach, adding 200 lb. of DDGS to a typical early grower diet (1,486 kcal ME/lb., 1.0% lysine, 0.55% P) will replace 162 lb. of corn, 36 lb. of 44% soybean meal, and 5 lb. of dicalcium phosphate (Table 3). Using prices shown in Table 3, this would result in a feed cost savings of $1.40/ton of complete feed over a typical corn-soybean meal diet with 3 lb. of synthetic lysine added. Under this scenario, you could afford to pay an additional $14/ton for DDGS ($99/ton) and break even with the cost of the typical diet.

   If a 10% DDGS diet is formulated on an apparent digestible amino acid basis using amino acid and available phosphorus values obtained from Minnesota research, you replace more corn (177 lb.), less soybean meal (19 lb.), and more dicalcium phosphate (7 lb.) compared to formulating DDGS diets on a total lysine and phosphorus basis. The net result is that because more corn ($3.57/cwt.) and less soybean meal ($9.50/cwt.) is being replaced by DDGS, the cost savings is reduced to 62¢/ton compared to the typical corn-soybean meal diet used in this report. This means that you could afford to pay an additional $6.20/ton for DDGS ($91.20) using this formulation method, and break even with the cost of the typical diet.

5. What are the total and available phosphorus values of your DDGS source?

   Like energy and amino acid levels, phosphorus levels can also vary — as low as 0.62% to as high as 0.87% (average: 0.78%). One of the primary reasons for variability is the variable amount of solubles (high in phosphorus) added to the distiller's grains before drying at various ethanol plants.

   University of Minnesota research places phosphorus availability at 90%, while the NRC (1998) lists the availability at 77%. Because of the economic significance of phosphorus in swine diets, and its impact on manure management plans, diets should be formulated on an available phosphorus basis. This approach takes advantage of the available phosphorus provided by DDGS, thereby reducing the need for supplemental dietary phosphorus and phosphorus excretion in manure.

6. Do you use phytase in your diets?

   As shown in Table 4, adding 225 FTU of phytase/lb. of complete feed and 376 lb. of DDGS (18.8%) to a swine grower diet (containing 0.85% total lysine), no supplemental dicalcium phosphate is needed when the diet is formulated on an available phosphorus basis. However, diet cost would be slightly increased by $0.11/ton compared to feeding a typical corn-soybean meal diet containing 3 lb. of synthetic lysine and no phytase. Using new generation DDGS and phytase is an economical and practical way to significantly cut phosphorus levels in manure.

7. How much DDGS do you want to use?

   Most pork producers who are feeding diets containing DDGS are using a rate of 5 to 10% in grow-finish and lactation diets, and up to 20% in gestation diets. Based on current feed ingredient prices, the cost savings increase as more DDGS is used.

However, when adding more than 10% DDGS, diets must be formulated on a digestible amino acid and available phosphorus basis in order to ensure good performance and to capture the economic savings. Using this approach, DDGS can be successfully fed at levels greater than 10% of the diet and support excellent pig performance while reducing phosphorus content in swine manure.

Finally, formulating on a digestible amino acid and available phosphorus basis results in a more conservative assessment of the economic value of DDGS in swine diets.

For more information on feeding DDGS, visit the University of Minnesota DDGS Web site: www.ddgs.umn.edu.