High levels of deoxynivalenol (DON), a mycotoxin commonly known as vomitoxin, are being found in grain across the Corn Belt, including eastern Iowa. Contaminated corn is an issue especially in dried distillers grains and solubles (DDGS), according to Erin Bowers, mycotoxin sampling and analysis specialist with Iowa State University.
DDGS, commonly used in livestock feed, is a by-product of ethanol production. Mycotoxins tend to concentrate in this by-product at three times the levels found in the original grain.
“This is problematic because we have a huge swine industry in Iowa, and swine are very sensitive to DON,” says Bowers. “When you feed DDGS that is contaminated at even 3 parts-per-million to swine in addition with other contaminated grains, you’re going to start seeing health and productivity issues.”
This compound is called vomitoxin because it can cause vomiting in swine, especially young pigs. The main negative effect of vomitoxin is feed refusal and reduced feed intake. Levels of DON acceptable in animal feeds vary by animal type, but generally beef cattle and poultry can tolerate higher levels than swine. Wet weather that favored mold development on corn ears in some areas of the Corn Belt prior to harvest last fall is the cause of the vomitoxin problem.
Feeding levels for livestock
DON is produced by molds of the genus Fusarium, most commonly Fusarium graminearum. According to the Food and Drug Administration, advisory levels for livestock consumption of DON are as follows (parts per million):
- 5 ppm DON on grains and grain by-products destined for swine with a recommendation that these ingredients not exceed 20% of the diet.
- For chickens, 10 ppm DON on grains and grain by-products with recommendation that these ingredients not exceed 50% of the diet.
- 10 ppm DON on grains and grain by-products (on an 88% dry matter basis) destined for ruminating beef and feedlot cattle older than 4 months and 5 ppm DON for ruminating dairy cattle older than four months.
- 5 ppm DON on grains and grain by-products destined for all other animals with the added recommendation that these ingredients not exceed 40% of the diet.
“In the eastern Corn Belt right now, we are seeing base corn levels around 1 part-per-million,” says Bowers. “As soon as you make DDGS out of that corn, you start pushing the boundaries of some feeding limits. Grain receiving locations should be testing for these levels or at least be aware that we are seeing higher levels this year. Having a good strategy for managing their grain supply and marketing it appropriately can increase its safe use.”
Using contaminated corn
There are solutions to using DON contaminated grain. Beef cattle are much more tolerant of this mycotoxin, and can be fed higher levels of contamination without seeing negative health or productivity effects. DON also can be blended, but steps should be taken to carefully and representatively test blended grain.
The Iowa Grain Quality Initiative has developed a set of online learning modules to help producers learn about mycotoxin sampling and handling. The Iowa Grain Quality Mycotoxin Development Module (CROP 3083F) and Iowa Grain Quality Best Practices in Handling and Testing Module (CROP 3083G) were produced in cooperation with the Iowa Grain Quality Initiative and Crop Advisor Institute.
Other available modules address grain storage economics, food safety and animal nutrition, supply chain analysis and processing. The modules are free and can be accessed on the Extension Store.
Source: Iowa State University