Processed feed

Distillers Grains: The Antibiotic Connection

Distillers grains, also known as “distillers dried grains with solubles” is a common ingredient in processed feeds. As the name implies, it is a byproduct of the distillation process, which until now I had safely assumed was nothing more than the “leftovers” of beer and spirit distilleries.

But a story on April 10, 2012 in Wired Science (followed two days later by an article in the Washington Post) brought the reality of distillers dried grains to my full attention…

Distiller's Grain

Distiller’s Grain


Distillers grains are a by-product of ethanol manufacturing. The massive amounts of GMO corn in the US are grown in part to support ethanol production. Making ethanol is a lot like brewing beer: you take a starchy carbohydrate (corn) wet it down to make a mash, warm it up, add yeast. Unfortunately it is common for the mash to become contaminated with bacteria such as Lactobacillus, which compete with the yeast for the sugars in the mash, but instead of producing alcohol, these bacteria leave behind lactic acid. This lowers the ethanol yield, so ethanol producers solve this problem by inoculating the mash with antibiotics.

Antibiotics Used:

The most common antibiotics used in the mash are penicillin, virginiamycin, erthromycin, tylosin and tetracycline.

After the Ethanol Yield:

The leftover mash is conveniently sold for animal feed (equine, swine, cattle, and chickens). In fact distillers grains have proven to be an economic boom to the ethanol producers.

Testing for Antibiotic Residue:

In 2008 the FDA tested 60 Dried Distiller Grain samples; of the 45 tested, 24 came back positive. Fifteen of the samples (33%) contained residues of virginiamycin,; 12 samples (27%) contained residues of Erthromycin, and five samples (11%) contained Tylosin. According to the FDA, “some were detected at levels considered significant, including residue levels exceeding 0.5ppm.”

Another study, (2011) not yet published, was conducted by the University of Minnesota; in that study, samples of dried distillers grains were collected from various ethanol plants. The samples, collected quarterly for a year were analyzed for antibiotic residue. All 117 samples contained antibiotic residue.

Distillers Grains: The Antibiotic Connection

Distiller’s Feed


Antibiotic Overuse:

Most of the news and uproar lately has been about antibiotic overuse as it relates to humans. The FDA released a statement/request on April 11, 2012 calling on drug companies to help limit the use of antibiotics in farm animals that scientist say has contributed to a surge in drug-resistant bacteria. Under the new FDA Guidelines, antibiotics for animals are to be used “judiciously” or only when necessary. An estimated 80% of all antibiotics sold in the US end up on animal farms.

The World Health Organization and the Institute of Medicine among others have called the waning effectiveness of antibiotics to be a global health concern.

However, the National Pork Producers Council recent response to the FDA’s request to drug companies to voluntarily limit the use of antibiotics was that “the FDA did not provide compelling evidence that antibiotic use in livestock is unsafe.”

I mention this quote from the National Pork Producers to highlight the challenges with factory farming: too many animals in confined spaces, increasing the health risks of those animals, and the increase in disease. The use of antibiotics on factory farms is immense. Factory farms want to continue with “business as usual”, despite requests from the FDA to reduce antibiotic use.

Antibiotic Residues in the Equine Diet:

To date there have been no studies on levels of antibiotic residue in horses from distillers dried grains or solubles. At this point we don’t even know how active or passive these residues are. In fact we know little about how antibiotic residue over time can affect our horses. The FDA has stated that it is concerned that antibiotic residues in distillers grains could be transferred to animal tissue upon ingestion.


Some ethanol plants have begun to use extracts from hops (yes, the same herb used to make beer), while other ethanol producers have started to use stabilized chlorine dioxide (Dupont) to combat the bacteria; thus eliminating the use of antibiotics all together.

Feed and Supplements:

By reading an equine feed label, or supplement label there is no way to know if the distillers dried grains are antibiotic-free or not. And no company at present has come forward to announce that they are “anti biotic free”. Maybe they all are antibiotic free, maybe some of them are, maybe none of them are. In September 2011, one ethanol producer who markets distillers grains under the label Dakota Gold, announced all it’s distillers grains were now antibiotic free. This particular company’s announcement was published in a cattle feed industry publication.

Dakota Gold Distiller's Grain

Dakota Gold Distiller’s Grain


From a Consumer’s Point of View:

We are not powerless against these suspect ingredients in equine feed and supplements. We can vote with our pocketbooks. We can demand from the feed companies we buy from, that they provide documentation of antibiotic free distillers grains. We can demand the same from supplement companies that use distillers grains. Or we can just stop buying any feed or supplement that contains distillers grains that are not labeled antibiotic free.

Keep in mind that these distillers dried grains and solubles are fed to chickens, swine, and cattle too. Which means if you are a meat-eater, buying conventional meat at the grocery store that is not organic, or not labeled antibiotic free, the residue antibiotics are most likely going to be in the meat you and your family eats. Increasing the possibility and likelihood of antibiotic resistance.

Antibiotics are important in the ongoing fight against harmful and deadly bacteria. To my mind, they need not to be in food.


Print Friendly, PDF & Email