Use Caution When Grazing Cornstalks, Feeding Baled Cornstalks
Generally, cattle are more tolerant of mycotoxins than other livestock; however, this fall more caution may be warranted.
The unusually wet fall and late harvest have resulted in mold and fungi in corn and cornstalks. Producers have asked about feeding the moldy corn grain, baled cornstalks and grazing cornstalks to cattle. The answer is not simple because mold does not always result in mycotoxins, and not all mycotoxins are harmful to cattle, according to Amy Radunz, University of Wisconsin-Extension beef specialist.
Generally, cattle are more tolerant of mycotoxins than other livestock; however, this fall more caution may be warranted, Radunz noted.
"The more dangerous molds of Fusarium and Gibberella have been reported in Wisconsin. Other molds of Diplodia or Penicillum are also present, but have lower risk of mycotoxin contamination," she added.
There have not been reports of high incidence of Aspergillus mold, which produces aflatoxins. This mold requires a very warm growing season to flourish, which Wisconsin did not have in 2009, but it could be a problem in some areas.
Fusarium mold will typically be white or pink in color and produce common mycotoxins of DON (vomitoxin), T-2, zeralenone, and fumonisins. Ruminants can break down some of the Fusarium mycotoxins in the rumen and exhibit few clinical problems; however, toxic levels of the mycotoxins can have negative effects on the animal.
Radunz said some clinical symptoms of high levels of mycotoxins include reduced feed intake, weight loss, skin or muzzle irritations/ulcers, diarrhea, poor response to antibiotic treatment and bloody diarrhea. In pregnant females, high levels of exposure to zeralenone can also result in abortions. Therefore, producers should avoid feeding moldy feeds to more susceptible animals, such as recently weaned calves and pregnant females. Molds or fungi can also release mold spores that can cause lung irritation. Pregnant cows fed and/or bedded on moldy vegetation potentially are susceptible to mold infections that can result in mycotic abortions.
If mold is evident, beef cattle producers should closely monitor cattle for these clinical signs and unusual behavior. Producers may want to avoid a field or parts of fields for grazing or baling if extremely high levels of molds are present on the stalks. If producers observe any of the clinical signs, they should quit feeding the stalks or grazing the field and provide another non-moldy feed. Supplementing the moldy feed with hay, grain, or other byproducts could dilute the mycotoxin's effects in the animal. Moldy baled cornstalks could be used as bedding, but it is recommended bedding the animals shortly after cattle are fed to prevent cattle from eating the bedding. It may also be a good preventative measure to unroll bales outside so the wind can blow the spores away, or make sure there is plenty of ventilation or air movement when bedding to help reduce mold spore content of the air that the cattle have to breathe.
Feed can be tested for mycotoxins, especially those mycotoxins that could negatively affect animal health. Mold within a field of corn can vary, with certain locations having higher concentrations of mold than other another location; therefore, a representative feed sample should be taken. A directory of additional resources, including laboratories that test for mycotoxins, can be found at http://fyi.uwex.edu/grain/.
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