AMES, Iowa -- Cattle producers who notice mold on bales of cornstalks should get them tested for toxins before using them for feed, an Iowa State University (ISU) Extension beef field specialist said today.
Heavy rains in October have affected the quality of cornstalks, which many producers use to lessen their winter feed costs. The extra moisture, however, has increased the chance for mold and mycotoxins, or toxins produced by fungi, to develop.
Beth Doran, ISU Extension beef field specialist, said she recommends cattle producers have a mycotoxin test conducted on cornstalks that show any noticeable signs of mold before using them as feed.
"Now if they don't see any visible mold, then chances are it's not going to be a problem," she said of mycotoxins.
Cattle are more tolerant than other animals, such as horses, to the most common mycotoxins associated with wet cornstalks -- fumonisins and vomitoxins, said Doran, who works with the Iowa Beef Center. However, she said she doesn't recommend providing any questionable feeds to animals that are more sensitive, such as breeding animals, young stock or stock that is more fragile due to health or age.
Consuming these mycotoxins should not result in major health issues for cattle, said Dr. Gary Osweiler, veterinary toxicologist at the Veterinary Diagnostic Laboratory at Iowa State.
Feed refusal is the only well-documented effect on cattle that consume vomitoxins, Osweiler said, and cattle are less likely to show effects from consuming fumonisins. Fumonisins are more toxic than vomitoxins, but cattle are fairly resistant to them in comparison to hogs and horses, he said.
"Even in bad years for fumonisins, we have never had an outbreak of fumonisin poisoning in cattle," Osweiler said.
Cattle can tolerate up to 100 ppm of fumonisins without any demonstrable problems, while long-term consumption of just 5-10 ppm is considered dangerous to horses, Osweiler said. Fumonisins in horses can cause a fatal disease called equine leukoencephalomalacia (ELEM), which destroys the animalÕs brain cells. And, even at low levels, fumonisins can cause liver disease, he said.
Therefore, Doran said horse owners should definitely have a mycotoxin test performed before using any questionable cornstalks for feed or bedding.
"With horses, I just wouldn't take the chance," she said. "Testing is a must."
To test for mycotoxins, Doran said the Veterinary Diagnostic Laboratory at Iowa State offers a qualitative test for $30 and a quantitative test for $35.
"I know that's $65, but that's pretty minor compared to reduced performance or the worst-cased scenario - a dead animal," Doran said.
Using affected cornstalks for bedding for cattle should be okay, Doran said. Producers should simply move the cornstalk bales in the pens after the cattle have been fed, so they will be less likely to consume the stalks, she said.
The Iowa Beef Center at Iowa State University was formed in 1996 by a legislative mandate. Its goal is to support the growth and vitality of the beef cattle industry in the state. As part of Iowa State University Extension, the Beef Center also serves as a central access point for all ISU programs and research related to the beef industry.
For more information about the Iowa Beef Center, visit www.iowabeefcenter.org.
Gary Osweiler, College of Veterinary Medicine, Iowa State University, (515) 294-1950,
Beth Doran, beef field specialist, Iowa State University Extension, (712) 737-4230,