Distillers’ grains are a by-product of grain-based ethanol production and can be a good energy and protein source for cattle. However, distillers’ grains are only cost effective when they can provide nutrients for a lower cost than other commodities, which depends on their availability, transport costs and current levels of bioethanol production. Most distillers’ grains in North America come from corn with some from sorghum and wheat. According to Renewable Industries Canada¹, as of 2020 the majority of Canadian bioethanol production occurs in Eastern Canada where almost 1.3 billion litres/year is produced as compared to Western Canada’s 810 million litres/year. Corn distillers’ grains are sold and produced primarily in Eastern Canada. Wheat distillers’ grains, or a mixture of wheat and corn, are produced in Western Canada.

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Production and Types

Distillers’ grains are the major by-product from the production of ethanol. To produce biofuels, cereal grains are heated and fermented. The starch is converted into ethanol and removed. The mixture of concentrated protein, fibre, oil and minerals, which remains is called stillage. Stillage is sold either wet (20 to 30% dry matter) 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).

DGS = Distillers' grains with solubles  DDGS = Dried distillers' grains with solubles WDGS = Wet distillers' grains with solubles

Typically, stillage is further separated into distillers’ grains and solubles. Solubles are recovered and incorporated into the distillers’ grains, called distillers’ grains with solubles (DGS). DGS can be used wet (WDGS) but is often dried (DDGS) in order to 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 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**
	Corn distillers’ grain	Corn grain	Wheat distillers’ grain	Wheat grain
Protein	32.4 to 34.5	9.8	30.6 to 44.7	14.2
Crude fat (oil)	5.6 to 8.3	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	0.75 to 1.21	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).

40% Wheat DDGS diet Photo credit: Lee-Anne Walter

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. Due to the various factors (grain type, moisture, solubles, milling and drying) that can influence composition, a feed test is recommended before using these by-products to feed beef cattle to determine the nutritional value of the DDGS (protein, fat, and energy content, etc). Producers may need to feed additional supplements or remove it from the feed plan entirely if certain nutrient levels aren’t met. This could lead to higher feed costs and overall expense for the producer.

Receiving and Handling

40% Corn DDGS diet. Photo credit: Lee-Anne Walter

DDGS can be transported and handled like other grain commodities. It is uneconomical to transport WDGS any great distance from a biofuel plant due to its high water content and short shelf life. This leads to more weight per load which then increases the cost of shipping. The brief shelf life also contributes significantly to the uneconomical nature of WDGS as producers have often observed spoilage during longer shipments, as well as during prolonged storage.

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), and
• it has been stored correctly with effective ensiling practices.

Feeding

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 Attributes

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.

DGS should not exceed 50% of a feedlot diet, because fat content of the complete diet for feedlot cattle should not exceed 6%. 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. This can mean that when there is a protein deficit from the basal diet, corn and wheat DGS can be more effective than soybean or canola meal in meeting the protein requirement of calves with a high protein demand, e.g. light weight and rapidly growing.

DGS are an excellent source of energy at levels up to 50% of the diet (dry matter basis). Once the animal’s protein requirements have been met, excess dietary protein is used for energy instead.

Due to the high levels of fibre in DGS, there has been interest in using DGS in place of dietary roughage. However, the DG fibre particles are too small to effectively maintain proper rumen function and health and have been associated with increased incidence of rumen acidosis and liver abscesses. It should be noted that DGS are not meant to be used as a roughage source, but rather a source for energy and protein.

A Canadian study by Yang et al. (2011)² found that a minimum of 10% barley silage was needed in a diet containing wheat DGS to prevent a rumen pH drop (increased acidity) in calves fed barley grain-based finishing diets.

Benefits for feedlot cattle

Corn WDGS enhances feed efficiency of corn-based diets by up to 13% with response proportional to the level in the diet up to 50% (dry basis). Corn DDGS enhances feed efficiency up to 5%, with the maximum response from between 10 and 20% inclusion in the diet. Overall, this increase in feed efficiency can lead to reduced costs if the DDGS are cheap enough. This is done mostly by reducing the amount fed, which either contributes to a larger profit margin or reduces losses for the producer. Other portions of the diet may need to be adjusted, based on a feed analysis of the distillers' grain, to meet the cattle's nutritional requirements.

At dietary inclusion rates up to 20% (20% of the animals' entire diet is DDGS), wheat DDGS provide similar feed efficiency to a barley-based control diet. Above 20% inclusion, wheat DDGS have had no effect or caused a slight decline in feed efficiency, by up to 9%. However, according to a study funded by BCRC, adding various feed enzymes to rations containing wheat DDGS was found to improve an animal’s digestion of dry matter, fibre and protein. The best results occurred with the addition of the enzyme called xylanase. Wheat DDGS could replace 30% of barley in a ration. Provided enzymes are added to the ration – 2 mL/kg of dry matter was the proportion used in the study – the results are significant. This ration improved feed efficiency (defined as daily gain per kg of feed intake) by up to 5%. This could reduce costs if the distillers’ grain is cheap enough. However, if it is cost prohibitive, DDGS dietary inclusion rates will need to be reduced.

DDGS can be composed of varying amounts of oil content that remains. This amount can either be found on the label or determined by a feed test. A recent study by Ribeiro et al. (2016)³ has shown that feed efficiency and average daily gain (ADG) can also be influenced by the residual oil content of the DDGS and when low oil content DDGS (oil content of 5.6%), versus medium oil content DDGS (oil content of 8.3%) is fed.

The study showed that low oil DDGS fed in growing diets increased ADG by 7% compared to higher oil content distillers' grains. Meanwhile, DDGS with higher residual oil content increased ADG by 2% compared to the low oil DDGS when fed in beef finishing diets. This shows that producers can maximize feed efficiency by using feed testing and the advice of a nutritionist to determine the DDGS oil content, and other nutritional values, so different distillers' grains can be incorporated at different times of the animal's growth cycle.

If a producer is formulating a ration for younger animals that are still growing, such as newly weaned calves, a low oil DDGS to maximize their ADG should be considered. Meanwhile older animals, such as yearlings or developed cows, who have finished growing benefit more from a medium oil content distillers' grain. This, however, may be uneconomical for the producer if alternative feeds that provide a similar nutritional value are available at a lower cost.

Concerns for feedlot cattle

Urinary calculi (kidney stones) is a symptom in male cattle of failing to balance the Ca:P ratio correctly resulting in too much phosphorus in a diet. In some cases, this imbalance can lead to the development of ‘waterbelly ’ in cattle, a condition that may also be seen with other feeds, not just DDGS. Symptoms of waterbelly include, frequent straining to urinate, prancing and/or kicking at the belly, and teeth grinding.

Phosphorus (P) levels are typically high in DGS. Dietscontaining DGS must be fortified with additional limestone over the amount used in grain diets to provide a calcium (Ca) to P ratio of at least 1.1 to 1, and preferably 1.5 to 1.

The Ca:P ratio is important as calcium and phosphorus both play important roles in the bodily functions of cattle. A decrease in either or both can cause a decrease in weight gain and/or a decrease in efficiency of gain. During lactation, low amounts of either will reduce milk production. A superior milking cow requires three times more calcium than a non-lactating cow. A phosphorus deficiency can delay puberty in heifers and can delay mature beef cows from returning to estrus following parturition. Cattle also need correct amounts of calcium for the nervous and muscular systems to function properly.

One of the symptoms of S toxicity in feedlot cattle, especially those fed barley-based diets is polioencephalomalacia, a neurological disease. Clinical signs depend on the area of the cerebral cortex affected and may include head pressing, blindness, anorexia, muscle tremors, teeth grinding, convulsions, and more.

Sulfur (S) levels are high in DGS and quite variable (0.35 to 1.4%). Levels of sulfur in the total diet (including water) above 0.4%, on a dry matter basis, can be toxic to feedlot cattle. Sulfur toxicity has not become a major problem so far with feeding DGS and has been the subject of a few recent research projects funded by the BCRC. The first study concluded that that up to 50% corn-based distillers’ grains plus solubles can be fed in a 90% concentrate finishing diet without adversely affecting animal performance, carcass weight, quality or yield grade. However, the effects on animal health were unclear. Because of this lack of clarity, BCRC funded a later study into the impacts DDGS has on animal health. That study found that sulfur toxicity can be easily avoided by testing feed to know its mineral levels and maintaining the DDGS at levels no higher than 40% of the diet.

Land required for the application of feedlot manure is increased when DGS is fed.

Because mineral levels in diets containing DG often exceed animal requirements, manure from cattle fed DGS are particularly high in nitrogen (N) and P. In the application of cattle manure from DGS fed cattle to agricultural land, nutrient management programs can be used to take soil and crop requirements into account in good management of manure from feedlot cattle. Cattle manure can be a valuable resource in agriculture when utilized properly. This is easily done thanks to commercial agricultural testing labs located throughout Canada that can test nutrient levels in soil and manure and provide application rate recommendations based on these results.

To learn more about the potential benefits and drawbacks of feeding distillers’ grains and other feed options to consider, visit our Alternative Feeds page.

Feeding DGS to feedlot cattle does not consistently affect carcass grade and meat quality. However, there are two points worth noting:

• Some studies have shown that DGS inclusion decreases marbling of meat, but this is not a consistent finding and it cannot be easily explained.
• According to a BCRC study, feeding DGS negatively affects meat colour and colour stability of beef in the retail case when aged slightly before display. The significance of this in affecting consumer satisfaction is less clear. This effect of feeding DGS in feedlot diets can be counteracted by providing additional vitamin E.

Feeding distillers’ grains to backgrounding cattle

DGS are an excellent energy and/or protein feed to use in completely mixed rations for backgrounding cattle for the feedlot. Calves fed forage/barley grain diets in western Canada where wheat DDGS has replaced most of the barley grain have performed equally to calves on the forage/barley control.

DGS can be an ideal supplement for calves grazing summer pasture, stockpiled wheat, or other forage in the late fall and early winter before being shipped to the feedlot.

Feeding distillers’ grains to cow-calf

DGS are an excellent energy source for supplementing any type of forage fed to cows and calves. Cows in mid-lactation have been fed as much as 15 kg (33 lbs) of WDGS daily. Precautions noted for feedlot cattle regarding phosphorus and sulfur must be noted in the feeding of DGS for cow-calf.