DDGS – A nutritionist’s view

A new raw material is pushing into the feed market. In 2005 in the USA alone, 9 million tons of DDGS was used, 75-80% of this as ruminant feed and about 20% was used as pig feed.

However, DDGS to DDGS differs significantly. It should be mentioned that each bio-ethanol plant produces a different quality of DDGS. DDGS stands for Dried Distillers Grains and Solubles, which is the Dried Residue from the distillation process. The composition and the nutritional value of the remains (DDGS) depends very much on the raw materials used (Wheat, Corn, Rye, Sugar beet, Sugar cane,...) and on the processing techniques, particularly on the drying temperature. The logic behind ethanol production is simple: Grain, Corn or even sugar cane is transformed into Alcohol, CO2 and DDGS. The fermentation and then the ethanol is produced from carbohydrates and sugars represented in the raw material. All the non fermentable substances such as crude protein, crude fiber, crude fat and minerals are left in the wet DDGS. These nutrients are also present after the drying process in two or three times the concentrations of the raw material. Thus the protein content of DDGS varies between Corn and Wheat with concentrations of 28% and 38% respectively. Unwanted substances from the raw material, such as mycotoxins, behave in a similar way to protein concentration. As these unwanted substances are not eliminated during the fermentation process, they come to a concentration around the factor of two to three.


How can DDGS become part of swine diets?

Due to the strong smell and taste of DDGS, it would be expected that pigs would avoid it and reduce feed intake. In order to provide answers to such questions, several feed trials were contacted at CAN (Biomin’s Trial Farm). During a recent trial 88 fattening pigs received either 0% DDGS during the entire fattening period or 10% DDGS in a Corn-Soya-Rapeseed-Ration. The DDGS was purchased from a bio-ethanol plant near Leipzig, which works predominantly with wheat, barley and rye. Both rations were adjusted to have identical vLys/MJ ME. Feed was given ad libitum throughout the trial and semi-ad libitum at the end of the fattening period. It was interesting to see that the animals accepted the taste of DDGS throughout the entire trial period and that the trial group had a higher feed intake than the control group (see Figure 1). Furthermore, the increased feed intake of the trial group lead to an increased turnover with daily weight gain of 826g which is slightly higher than the control group. The feed utilization was similar for both groups - 2,88. The fact that the lean meat for the trial group was 0.85% lower than the control group, suggests that digestibility of 60% for crude protein was over estimated. However, it is to be expected that the inclusion rate of 10% - as applied in this trial - could be further increased.


Figure 1: Daily feed intake for the trial group (Biomin Research, 2007)






From a nutritional point of view DDGS is an interesting raw material for fattening pig diets and can be used up to 15% of the diet. A healthy, fully developed digestive system is essential if DDGS is to be included in the diet. The inclusion of DDGS in piglet rations must meet this condition, since undigested particles end up in the last parts of the digestive tract and are wasted.

Other considerations should also be taken into account before including DDGS in the diet. These are:

• Since the protein is denaturized during the fermentation and the drying process the protein digestibility should be included in the ration formulation which includes DDGS. Protein digestibility ranges between 40 and 70%. This has a corresponding influence on the ration formulation and the cost value of DDGS. When using DDGS the four first limiting amino acids (lysine, methionine, threonine and Tryptophan) are not the limiting factors, since these can be supplemented synthetically. Limiting factors are the essential subsequent amino acids (Valine, Isoleucine,…) which can not yet be supplemented synthetically. In low-Nitrogen diets these amino acids soon become limited and are also the limiting factors for muscle building. It is assumed that DDGS (inclusion of more than 5% in the ration) and a low-nitrogen diet are mutually exclusive.
  
  
• Feed hygiene: Mycotoxin contaminated DDGS can cause a problem in the concentration of unwanted substances. A corn initially contaminated with 600ppb DON, after ethanol production the remains (DDGS) will have a contamination of 1500ppb! Other Mycotoxins behave in the same way and due to the risk of ZON on breading sows DDGS is to be avoided.
  
  
• The DDGS mentioned earlier contains the fatty acids of the original raw material. Corn based remains (DDGS) contain a corresponding fraction of polyunsaturated fatty acids which have to be considered by some meat brands. Furthermore, these fatty acidsare susceptible to oxidation which minimizes the shelf-life of DDGS.
  
  
• DDGS represents an additional component in the agricultural enterprise / farm. This still requires additional raw materials in the feeding plant, since DDGS Soya can not completely replace protein carriers. The current situation for the Crop and Soya market requires an appropriate flexibility for purchases. With the additional silo components there is a higher flexibility of buying and feeding favorably available raw materials at a short notice.
  
  
• In combination with alternative sources of protein: Due to its own taste, the amino acids in combination with the crude fiber content limits rapeseed meal pellet extraction or soya pellet extraction. The sum of these components should not exceed 15% for pig diets.
  
  
• Cost value: The cost value of DDGS orients itself – like all alternative sources of protein – at the current market prices of Sojaschrot and grain. It is important to compare the raw materials on the basis of their digestible nutrients. As a guide for DDGS cost, a simple equation can be used to estimate its cost value. The use of DDGS as a component of the feed depends on the above conditions.

DDGS offers a relatively new source of protein, which can be interesting if included in pig diets. Data from the USA can not be used for Europe due to the different pig diets and expectations for lean meat percentages. In order to introduce DDGS correctly in pig diets, under European conditions, Biomin Austria has already made attempts to introduce DDGS in raising piglets – with this knowledge and the co-operation with colleagues in the US a product line for DDGS diets will be developed.