Monitor the mycotoxins in your fields this harvest

2012-09-26T16:04:00Z Monitor the mycotoxins in your fields this harvest Farm and Ranch Guide
September 26, 2012 4:04 pm

Plagued as the most severe and extensive drought in 25 years by the United States Department of Agriculture, this year's weather and climate conditions have wreaked havoc on more than 62 percent of the nation's farms.

Declared drought disasters by the USDA, these areas of the U.S. may see crop yields reduced by 60 to 100 percent. Even in areas where loss may not be as staggering, farmers will still be watching out for increased nitrate and mold levels.

According to Dr. Swamy Haladi, global technical manager of the Alltech Mycotoxin Management Team, drought not only causes obvious losses in crop yield but brings more mycotoxins to the farm as plants become stressed and more susceptible to diseases.

"It is not just excess rain that brings with it the increased mycotoxin challenge but historically the worst mycotoxin years are also drought years," Haladi said.

Mycotoxins are harmful compounds produced by molds (fungi) that are found in soil and can grow on vegetable matter including grain, forages and silages. Mycotoxins can be formed in the field preharvest and may continue to be formed under suboptimal storage conditions postharvest.

Temperature is an important factor influencing mold growth and mycotoxin production and plants stressed by drought and high temperatures are commonly invaded by mold spores which can produce mycotoxins.

Insect challenge in the field is directly proportional to temperature and such damage reduces the plant protection against molds. The fact that some of the crop producers are not spraying fungicides to keep the cost down is not helping the cause.

"The global climate change has resulted in climatic extremes which are increasing the frequency of mycotoxin contamination we are seeing in our cereal grains, forages and silages," Haladi said.

No matter what the cause, all the elements associated with drought are precursors for Aspergillus and some of the Fusarium molds such as Fusarium verticilloides and Fusarium moniliforme. Aspergillius molds produce Aflatoxin B1, the notorious carcinogen mycotoxin regulated by the FDA.

Haladi recommends producers take field checks to look for grayish, yellow green mold near the tips of or all over the ears. Producers should check in several areas of the field and not just one.

While the Midwest may be used to seeing incidences of vomitoxin (DON) and zearalenone, Haladi warns that this year may be worse due to the dry conditions and insect damage. Such conditions allow some Fusarium molds to produce another group of mycotoxins called fumonisins. These toxins can compromise immune and gut systems at lower concentrations but cause pulmonary edema (fluid accumulation in lungs) at higher concentrations.

According to Dr. Elizabeth Santin in The Mycotoxin Blue Book, Fusarium species can survive in corn residue, which is probably the most important source of inoculums for kernel infection. These fungi can be associated with every part of the corn plant and 50 to 100 percent incidence of kernel infection is not uncommon, with the majority of kernels showing no visible damage.

This year's corn harvest may also suffer from additional setbacks. Many experts have recommended that farmers let the corn plants grow more and not chop too early to aid in nitrates. However, farmers should still monitor moisture levels.

"Silage that is too dry, less than 65 percent moisture, will not pack well," Haladi said. "This situation can increase the chances of Penicillum molds from making an appearance in our silage. Unlike other mycotoxins, these silage mycotoxins can act as antibiotics and kill beneficial microbes in the rumen. The net result is lowered productivity."

Haladi also warns if producers are cutting the silage lower to increase tonnage, they may also be increasing the amount of soil contamination and thus further increasing the amount of mold spores.

"Producers should positively identify any situations that may arise with this year's corn crop and not assume it is only Aspergillius," Haladi said.

In order to indentify more of the risks associated with mycotoxins, Alltech recently launched its 37+ Program. The mass spectrometry technique LC-MS2 can investigate 38 different mycotoxins quantitatively, and more than 50 others qualitatively in less than 15 minutes per sample analyzed, with limits of detection in the parts per trillion range.

"This approach allows us to have a broader analytical approach compared to the other commercial methods that can only see a "snapshot' of contamination," Haladi said.

Once mycotoxins have made their way into the feed, there are still a few options available to the producer. They either should not feed the contaminated feed or should use an effective mycotoxin adsorbent.

There are two types of adsorbents: silica-based polymers and carbon-based organic polymers. Silica-type materials, such as clays, are readily available and many have shown to be effective against aflatoxins, but ineffective against other types.

Haladi recommends an organic mycotoxin sequestering agent that can be used at practical levels of inclusion for all species of mycotoxins, including DON.

"Our livestock remains the best indicator of a mycotoxin presence," Haladi said. "If an animal is not performing to its fullest or unexplained symptoms persist; consider the role that a mycotoxin may be playing."

Copyright 2015 Farm and Ranch Guide. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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