Harvest and Storage Tips to Limit Mycotoxins Growth in Corn
Certain parts of the Corn Belt experienced extreme weather and temperature conditions, leading to damaging levels of ear rot. If you’re one of those farmers be sure to test corn for Mycotoxins and, if you have them, keep them below threshold.
It starts at harvest.
“Adjust combine settings to minimize damage to grain. High dew points are limiting storage aeration and mycotoxin levels can increase rapidly in high moisture corn,” according to a recent publication by Charles Hurburgh and Alison Robertson with Iowa State University Extension. “One research study reported a 77% increase in fumonisin levels in 25% moisture corn over seven days.”
- Damaged kernels are infected faster than whole kernels. Cracks and splits serve as entry points for the fungus. In some cases, corn that shows high levels of Mycotoxins can be reduced by filtering out those broken and chipped kernels in storage.
- If you harvest high-moisture corn to salvage yield be prepared to dry it down quickly to avoid spreading toxins further.
- Storage time for poor quality or damaged grain needs to be reduced by half, according to ISU. Because mold and Mycotoxin issues are worse in broken grain consider using core bins (without spreader) to remove the majority of broken kernels and fines to improve airflow.
- Getting grain to an appropriate moisture and temperature can slow or stop the spread of Mycotoxins and other molds, but it’s not curative. The mold will stay on the grain regardless of what you do, so it might be valuable to blend infected grain with uninfected grain to reduce the toxin levels to an acceptable level.
(Chart Credit: Iowa State University)
Experts at Philbro Animal Health Corporation encourage farmers and livestock owners to look at corn Mycotoxins from “A to Z.”
- Aflatoxin (AF), produced by an Aspergillus mold, can occur due to drought stress and is more common in high-temperature areas. The main concern with AF is an illegal milk residue (> 0.5 ppb) that can occur if the TMR contains greater than 20 ppb AF. The primary target of toxicity is the liver.
- Aspergillus ear rot is associated with aflatoxin.
- Deoxynivalenol (DON) is a marker for feeds naturally contaminated with mycotoxins and has been associated with poor feed intake, digestive upsets, intestinal damage, diarrhea, increased incidence of disease and lower milk production in dairy cows. Effects of mycotoxin-contaminated feeds are generally chronic, resulting from prolonged intake of low levels of multiple mycotoxins.
- Fumonisin is toxic to cattle only at very high concentrations; however, when co-occurring with other mycotoxins, it can reduce feed intake and increase liver damage.
- Fusarium or "pink ear rot" is white or pinkish and is associated with fumonisin.
- Gibberella or "red ear rot" is associated with the mycotoxins deoxynivalenol (DON) and zearalenone (ZEA). A small percentage may be Fusarium sporotrichioides producing T-2 toxin.
- Other mycotoxins may contaminate fungal damaged corn. There are hundreds of mycotoxins produced from a variety of molds. When one mold infects the corn crop, many others are often present, which can produce multiple mycotoxins and increase the possibility of toxicity.
- T-2 toxin is a Fusarium-produced mycotoxin that has been seen most often with late-harvested or over-wintered corn. T-2 toxin is very irritating to epithelial tissues. It is associated with reduced feed intake, lower production and intestinal distress. T-2 toxin has been found in feeds associated with a hemorrhagic bowel syndrome different from that associated with Aspergillus.
- ZEA causes estrogenic effects in cattle. ZEA can increase estrogenic activity, including edema, swollen reddened vulva and fluid accumulation in the udders of virgin heifers. Pregnancy and conception rates may be reduced, and there may also be an increase in early embryonic deaths, irregular estrus periods and cystic cows.
