Product Descriptions
Many feed products can result from the
ethanol production process. They are described here. Choose
a category to go directly to information about:
- Co-Products of the
Dry Milling Industry (distillers grains and solubles)
- The Average Nutritional
Profile of DDGS
- Co-Products of the Wet Milling Industry (extractives, germ meal,
gluten feed, gluten meal)
If you would like to purchase ethanol co-products, contact information for marketers can be found on the Resources page.
Co-Products
of the Dry Milling Industry
Corn is about two-thirds starch, which is converted to ethanol and
carbon dioxide during a distilling and fermentation process. The remaining
nutrients in corn, such as protein, fat, minerals and vitamins, are
concentrated in three different ways and end up as distillers grains
or condensed distillers solubles. Distillers grains are a co-product
of the dry mill process used to make ethanol from corn (view
dry grind ethanol process chart).
- Corn distillers grains contain the remaining
nutrients after the corn starch is fermented to alcohol. The distillers
grains can be sold wet or dried. Wet distillers grains are higher
in protein and energy than corn gluten feed because gluten and oil
remain in distillers grains. When distillers grains are dried they
lose some energy value compared to wet products. Dried distillers
grains and dried distillers grains with solubles are marketed widely
around the world as a feed commodity.
- Corn distillers dried grains (DDG) is obtained
after the removal of ethyl alcohol by distillation from the yeast
fermentation of a grain or a grain mixture by separating the resultant
coarse grain faction of the whole stillage and drying it by methods
employed in the grain distilling industry.
- Corn distillers dried grains/solubles (DDGS)
are recovered in the distillery and contain all the nutrients from
the incoming corn minus the starch. Thus, the DDGS has at least
threefold the nutrients as the incoming grain. Since the stillage
is recycled, the ratio of these more valuable amino acid types continues
to increase so that eventually they represent approximately 16%
of the final DDGS's amino acid content. No other feed ingredient
results from such a great percentage of microbial products and their
back stocking. DDGS typically analyzes at 27% protein, 11% fat and
9% fiber.
- Corn condensed distillers solubles (CDS) is
a term generally used to refer to the evaporated co-products of
the grain fermentation industry. Most of the CDS is added to the
dried grains, but some is available as a liquid feed ingredient.
On a dry matter basis CDS typically is 29% protein, 9% fat and 4%
fiber. The solubles are an excellent source of vitamins and minerals,
including phosphorus and potassium. CDS can be dried to 5% moisture
and marketed, but generally the dry matter content is between 25-50%.
- Wet distillers grains (WDG) can be sold as livestock feed or dried into distillers grains (DDG). If syrup is added to wet distillers grains and dried, the resulting product is referred to as distillers dried gains with solubles (DDGS).
Average
Nutritional Profile of DDGS
As starch is removed for conversion to ethanol, fat, minerals, vitamins
and fiber are present in the spent grains at a higher proportion.
Ethanol production results in a higher concentration of nutrients
present from the corn, as well as synthesis of other nutrients. The
yeast used to ferment the starch contributes positively when added
back to the grains in the form of solubles.
This concentration of protein, fiber, fat and minerals enhances the nutrient viability and value of DDGS as a specialty ingredient in the ration because of lower inclusion rates in the diet. By feeding a lower inclusion rate feedstuff, more space is left in the ration to meet the animal's nutritional requirements without exceeding recommended daily total dry matter intake.
Today, there is not a standard test done for distillers grains. AOAC standards are being considered for adoption by the ethanol industry to provide consistency. The University of Minnesota recently gathered samples from Midwest plants to perform the AOAC test and compare nutritional profiles. To read about the Midwest plant nutritional profiles, visit the University of Minnesota's website.
Co-Products
of the Wet Milling Industry
Wet-milling (view
wet milling process chart) produces four major co-products for
the feed industry from the isolated steep water, bran, germ meal and
gluten. Together these co-products represent about 25%-30% of the
corn processed.
- Condensed corn fermented extractives or corn
steep liquor is a high-energy liquid feed ingredient. The protein
value analyzes at 25% on a 50% solids basis. This product is sometimes
combined with the corn gluten feed or may be sold as a pellet binder
and is a source of B-vitamins and minerals.
- Corn germ meal is golden-yellow and is mainly
gluten, the high-protein portion of the corn kernel. Corn
gluten meal typically analyzes at 20% protein, 2% fat and
9.5% fiber. It has an amino acid balance that makes it valuable
in poultry and swine rations. It is also used as a carrier of liquid
feed nutrients.
- Corn gluten feed is an intermediate protein
product that is rich in highly digestible fiber. It may or may not
contain the condensed corn extractives. This product is sold as
wet or dry. The bran and condensed extractives (sometimes germ meal)
are combined and dried in a rotary dryer. The dried corn gluten
feed is made into pellets to facilitate handling. It analyzes typically
as 21% protein, 2.5% fat and 8% fiber. Wet
corn gluten feed (45% dry matter) is similarly combined but
not dried. It is a perishable product in 6-10 days and must be fed
or stored in an anaerobic environment. These feeds are widely used
in complete feeds for dairy and beef cattle, poultry, swine and
pets.
- Corn gluten meal is a high-protein concentrate typically supplied at 60% protein, 2.5% fat and 1% fiber. It is a valuable source of methionine. Corn gluten meal also has a level of xanthophylls, which offers the poultry feed formulators an efficient yellow pigmenting ingredient. Corn gluten meal also is excellent cattle feed providing a high level of rumen bypass protein.