Dried distillers grain is a high-protein animal feed made from the leftover material of ethanol production. When corn or wheat is fermented to produce ethanol fuel, the starch gets consumed, but the protein, fat, fiber, and minerals remain. That leftover material, once dried, becomes one of the most widely used feed ingredients in the livestock industry. In 2024, U.S. ethanol producers generated 36 million metric tons of distillers grains and related co-products, with exports reaching more than 50 countries.
How Distillers Grains Are Made
The process starts at a dry-mill ethanol plant, where corn is ground into a fine flour and mixed with water and enzymes. Yeast ferments the starch in that mixture into ethanol and carbon dioxide. Once the ethanol is distilled off, what’s left behind is called “whole stillage,” a wet, grainy material containing everything the yeast didn’t consume.
That stillage gets separated into two streams: the solid portion (wet distillers grains) and a liquid portion (thin stillage). The liquid can be condensed into a syrup called condensed distillers solubles. When the syrup is mixed back into the wet grains and the whole thing is run through a dryer, the result is dried distillers grains with solubles, commonly abbreviated DDGS. Without the solubles added back in, the product is simply DDG. DDGS is the more common commercial form because the added solubles boost its energy and nutrient content.
The drying step is what gives the product its long shelf life and shipping flexibility. Wet distillers grains contain so much moisture they spoil within 3 to 7 days, which limits their use to farms near ethanol plants. DDGS, dried down to about 10% to 12% moisture, remains stable for up to a year and can be shipped anywhere in the world.
Nutritional Profile
Because fermentation strips out most of the starch, the remaining nutrients in the grain get concentrated roughly threefold. That’s why DDGS packs significantly more protein than the original corn or wheat it came from.
Corn-based DDGS typically contains 32% to 35% protein, 6% to 8% fat, and 34% to 48% fiber on a dry basis. Wheat-based DDGS runs higher in protein (31% to 45%) but lower in fat (about 4%). Both types are considerably richer in protein than whole corn, which sits around 8% to 10%. This makes DDGS a cost-effective substitute for more expensive protein sources like soybean meal.
One important nutritional detail: the concentration process also triples the mineral content, particularly phosphorus and sulfur. High phosphorus can be beneficial for animal nutrition but creates challenges for manure management, since excess phosphorus accumulates in cropland soil around feedlots. Sulfur levels also rise substantially, which requires careful attention when formulating cattle diets because too much sulfur can cause neurological problems in ruminants.
Which Animals Eat It
DDGS works in diets for beef cattle, dairy cows, hogs, and poultry, though the recommended inclusion rates vary by species and production stage.
- Beef cattle can handle the highest levels, typically 20% to 40% of total diet dry matter. At 40% inclusion, some research suggests a reduction in methane emissions from digestion, though nitrous oxide emissions may increase as a trade-off.
- Dairy cows do well with 10% to 30% of the ration as DDGS without loss of milk production or changes in milk fat and protein content.
- Swine can be fed up to 30% DDGS in grower-finisher diets, though 20% is often recommended because higher levels can produce softer pork fat and affect belly firmness. Breeding sows can receive 10% to 50% in gestation diets and up to 30% during lactation.
- Poultry are the most limited, with recommended maximums of 10% to 15% for layers and about 10% for broilers and turkeys.
Ruminants like cattle digest DDGS more efficiently than monogastric animals like pigs and chickens, largely because their rumen bacteria can break down the fiber fraction. That’s why cattle diets tolerate much higher inclusion rates.
Price and Economic Value
DDGS fills a unique niche in the feed market because it can partially replace both corn (as an energy source) and soybean meal (as a protein source) in a single ingredient. Every bushel of corn processed at an ethanol plant yields about 18 pounds of DDGS.
From 2007 through 2024, DDGS averaged around $173 per ton, nearly identical to corn’s average of $167 per ton over the same period. Soybean meal, by comparison, averaged $363 per ton, making it roughly twice as expensive. For livestock producers, this price gap makes DDGS an attractive way to add protein to rations without paying soybean meal prices. Projections for late 2025 and early 2026 place DDGS prices in the $145 to $155 per ton range.
DDGS prices track closely with corn prices, which account for about 55% of the variation in DDGS pricing. Soybean meal prices explain another 24%. So when corn gets expensive, DDGS does too, but it generally remains cheaper than buying corn and soybean meal separately to achieve the same nutritional profile.
Storage and Handling Considerations
At 10% to 12% moisture, DDGS stores well in conventional grain bins and commodity buildings. The main challenge is flowability. DDGS particles tend to bridge and clump, especially if they absorb moisture from humid air. Higher moisture increases compressibility and makes the product harder to move through augers and bins. Keeping storage areas dry and well-ventilated prevents most handling problems.
While some sources describe the shelf life as “almost indefinite” under ideal conditions, a practical maximum of about one year is a better planning figure. Wet distillers grains, which some feedlots near ethanol plants use to save on drying costs, need to be fed within days of delivery.
Environmental Trade-Offs
Using DDGS in livestock diets reduces the industry’s dependence on imported soybean meal and dedicated feed-grain crops, which lowers the overall carbon footprint of meat and milk production. A large-scale meta-analysis found that DDGS inclusion does not significantly increase methane emissions from cattle digestion, despite earlier concerns that its fat and fiber content might alter rumen fermentation in problematic ways.
The bigger environmental issue is nitrogen and phosphorus excretion. Cattle fed DDGS-heavy diets excrete substantially more nitrogen, phosphorus, and sulfur in their manure. Phosphorus excretion increases and retention decreases as DDGS replaces more of the base diet. For feedlot operations, this means manure management plans need to account for higher nutrient loads to avoid accumulation in surrounding cropland and potential runoff into waterways.