Feeding Ethanol Co-Product Dried Distillers' Grains with Solubles (DDGS) to Livestock: Implications for Animal Health, Crop Production, Soil, Water, and Air Quality.

In response to high oil prices, climate change, and government bio-energy initiatives, ethanol production, as well as the availability of dried distillers’ grain with (or without) solubles (DDGS), has increased in North America. Successful marketing of DDGS is critical to the economic viability of the ethanol industry. Following removal of starch during ethanol production, the nitrogen, fiber, fat and mineral contents in DDGS are higher than in unprocessed grain. DDGS has been incorporated successfully into diets for beef cattle, dairy cows, hogs, poultry, and horses. More DDGS has been used in diets for cattle (at up to 60% of dry matter) than for other livestock because ruminants have the ability to utilize fiber more efficiently. Performance and meat quality were generally unchanged or improved with diets that contained moderate levels of DDGS. However, DDGS may cause unforeseen alteration in the microbial ecology of the digestive tract. There is evidence that including DDGS in the diet may promote cattle shedding the human pathogen, E. coli O157. There is also evidence that the higher fat levels in some forms of DDGS may lower the amount of methane emitted by ruminants. Including DDGS often results in the diet exceeding the N and P requirements of cattle, thereby increasing N and P content in manure. Although this can be beneficial if the rate at which manure is applied do not exceed the requirements of the crop, higher N levels in manure will likely also increase the release of ammonia during manure storage and land application. Increased P levels in manure also means a larger land base would be required to avoid its accumulation in soil and the risk of water pollution. Thus, manure management practices should be adjusted to account for compositional changes in manure so as to minimize any negative impact that the feeding of DDGS to livestock may have on the environment.