David P. Price is a consulting nutritionist specializing in feedlot and range cattle
When oil went over $100/bbl the explosion in ethanol production led to an equal explosion in the amount of spent grains available for feeding. We have discussed the inefficiency of corn ethanol production in a previous column. But regardless how foolish the politics of “biofuels” are, the byproduct is a superb feedstuff.
Dried distillers grains (DDG) are high in protein (normally somewhere around 30 per cent), high in phosphorus (.4 to .5 per cent), usually high in fat (about 10 per cent) and rich in highly digestible fibre. Because of the oil content, distillers grains usually are higher in energy than corn. Beyond that, they are highly palatable. Because of the palatability (and the rich nutrient content) they make excellent carriers in feeds for finicky species such as bison, or wild ungulates such as deer.
In the marketplace there is DDG and what is known as DDGS. DDG is pure dried distillers grains, whereas DDGS is DDG with added distillers solubles. Solubles, as the name implies, is the watery runoff from the fermentation of grains for ethanol. While very high in moisture, solubles are also an excellent feed; not as high in protein as the grains (usually about 18 per cent), much higher in phosphorus (often 1.0 per cent or even higher) and usually much higher in fat. Because of the high moisture, solubles are often a liability to the plant. Unless there are feedlots or dairies nearby, their only option is adding the solubles back to the grains and dehydrating them.
When solubles are added back, the nutrient profile of the final product changes. DDGS will have less protein than DDG, but more phosphorus, fat and subsequent energy.
But the variability goes beyond how many solubles are added back. To begin with, ethanol can be made from barley, sorghum (or potatoes). In those cases there will be much less oil (and energy). Beyond that, some plants have the ability to remove the oil from corn DDG, and thus even corn-based DDG and DDGS can be low in oil.
Unlike commodities such as soybean meal or canola etc., there are no industry standards for the nutrient profile. This is because DDG and solubles are not “products” so much as they are byproducts. Ethanol is the main focus of the plant and the spent grains are the aftermath.
Some plants have less drying capacity than others. As a result, some plants dry their spent grains more rapidly and/or apply excessive heat, heat which can denature the proteins.
Colour is a quick check as to whether excess heating has occurred. If the sample is bright yellow, this indicates proper heating and drying. A darker colour can indicate either excess heating, or a heavy addition of solubles — as solubles will also darken the product.
When the extent of the amount of product to be released on the market was evident, I was contracted to teach Japanese and Latin American nutritionists how to formulate with DDG and DDGS. To illustrate the variability in drying, I called seven feed mills providing supplements for clients and requested a sample of the DDG or DDGS used by each plant.
Below is a photo of the samples.
Clearly the two yellow samples on the left were dried properly. The samples in the middle could have been either overheated or contain large amounts of solubles. The sample on the far right, however, was without question overheated.
What is strange is that animals often prefer overheated feeds. If used primarily to increase the palatability of feeds, the product on the far right would be an appropriate choice. Indeed, the feed mill using the far right sample manufactured free-choice minerals for a number of clients running bison; with excellent consumption and results.
In short, DDG and DDGS are superb feed ingredients. They are, however, byproducts rather than commodities and therefore there are no standard nutrient profiles. One therefore cannot negotiate solely on price, but must obtain guarantees from each supplier before an intelligent price can be offered or accepted.