Nutrition of Beef Distillers Grain Distillers’ grains are a by-product from the process of grain-based ethanol production and can be used as an economical commodity in feeding cattle. As long as bioethanol production continues at current levels, the feedlot industry in Canada will feed distillers’ grains in order to produce beef as efficiently as our trading partners. Most distillers’ grains in North America come from corn with some from sorghum and wheat. Corn distillers’ grains are sold produced in Eastern Canada and the U.S. Wheat distillers’ grains, or a mixture of wheat and corn, are produced in Western Canada. Bioethanol production will Production and Types generate Distillers’ grains are the major by-product from approximately 1.8 the production of ethanol. To produce biofuels, million tonnes of cereal grains are heated and fermented. The starch dried distillers’ is converted into ethanol and removed. The grains with mixture of concentrated protein, fibre, oil and solubles (DDGS) in minerals, which remains is called stillage. North America this Stillage is sold either wet (20 to 30% dry matter) year. or dry (90% dry matter). Stillage remaining after the fermentation and distillation process is low in solids and is sometimes fed directly to livestock through the watering system (thin stillage). Typically, stillage is further separated into distillers’ grains DGS: Distillers’ grains with and solubles. Solubles are recovered and solubles incorporated into the distillers’ grains, DDGS: Dried distillers’ called distillers’ grains with solubles grains with solubles (DGS). DGS can be used wet (WDGS) WDGS: Wet distillers’ grains but is often dried (DDGS) in order to with solubles reduce shipping costs. Composition There is considerable variation in the composition of distillers’ grains. Composition may be partially reflected by whether grain is processed by dry or wet milling before it is fermented. Because starch is almost completely removed in the process to distill ethanol, concentration of other components, except calcium, is enhanced significantly. For example, fat, protein, fibre, phosphorus and sulfur are roughly are three times as concentrated in DDGS than in the original grain. Steer after consuming 40% Corn DDGS diet. Photo credit: Lee-Anne Walter COMPOSITION OF DISTILLERS’ GRAINS* AND PARENT GRAIN, % DRY BASIS** WHEAT DISTILLERS WHEAT GRAIN DISTILLERS CORN GRAIN GRAIN GRAIN Protein 29.4 to 32.0 9.8 30.6 to 44.7 14.2 Crude fat (oil) 10.0 to 11.8 4.1 3.7 to 4.4 2.3 Fibre (NDF) 34.1 to 48.1 10.8 22.7 to 36.5 11.8 Calcium 0.02 to 0.03 0.03 0.02 to 0.03 0.05 Phosphorus 0.68 to 1.10 0.32 0.83 to 0.95 0.44
*Encompasses both wet and dry distillers’ grains
** Corn and wheat distillers’ values from Lethbridge Research Station, University of Saskatchewan and Spiehs et al. Journal of Animal Science (2002) vol. 80, p.2639. Grain values from NRC, Nutrient Requirements of Beef Cattle (2000). Dietary starch, fibre and protein levels can affect the pH of a ruminant’s digestive tract, which may in turn affect how well various microbes survive and compete in the animal’s rumen, intestine and manure. This can effect animal health and welfare, food safety and feed efficacy. The manner in which DDGS are dried can also affect nutritional value. 40% Wheat DDGS diet Due to the various factors (grain type, Photo credit: Lee-Anne Walter moisture, solubles, milling and drying) that can influence composition, chemical analyses are recommended before using these by-products to feed beef cattle. Receiving and Handling DDGS can be transported and handled as any grain commodity. It is uneconomical to transport WDGS any great distance from a biofuel plant. WDGS may deteriorate quickly in the open. WDGS may be stored for many months with under 10% loss of nutrients if: •In a bunker silo (either alone or in combination with wet processed grain or forage) •With effective ensiling practice 40% Corn DDGS diet
Feeding Photo credit: Lee-Anne Walter DDGS and WDGS are both very palatable when mixed into a complete feed, or fed as a supplement that is top-dressed onto the base diet. DDGS and WDGS can be fed without mixing into a ration, preferably from troughs but also off frozen ground, as a forage supplement. Feed Atributes DDGS are widely used in feedlot rations throughout North America because it reduces feed costs. The expansion of North America’s ethanol industry has increased feed grain costs and subsequently increased the use of distillers’ grains as livestock feed. DGs can be a valuable source of dietary protein or energy for cattle, depending how they are fed. At levels generally below 15% of the diet, dry basis, DGS is an excellent alternative to soybean or canola meal as a protein supplement. DGS is relatively high in rumen bypass protein with DDGS having slightly more than WDGS. DGS should not exceed This can mean that when there is a protein 50% of a feedlot diet, deficit from the basal diet, corn and because fat content of wheat DGS can be more effective than the complete diet for soybean or canola meal in meeting the feedlot cattle should not protein requirement of calves with a high exceed 6%. protein demand, e.g. light weight and rapidly growing.At levels up to 50% of the diet, dry basis, DGS is an excellent source of energy. Once the animals protein requirements have been met, excess dietary protein is used for energy instead.
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