Posts tagged ‘mycotoxin’

Precautions for Handling Moldy Grain

Poor quality and mycotoxin infested grain is common this year with some growers reporting very low levels to very high levels.  Purdue University recently published a short article on grain safety handling:

Breathing grain dust is never healthy, and grain handlers should always wear protective masks when they work in grain bins, and when conducting operations that generate dust. Grain damaged by ear rots will have higher levels of dust and fines present, compared to good quality grain. Fungal spores produced by the ear rot fungi will also be in the grain dust. Fortunately, the fungus that causes Gibberella ear rot does not produce a lot of spores. However, there will certainly be spores of other molds in the grain dust. These spores can lead to allergic reactions, which may include flu-like symptoms, if workers do not take precautionary measures to protect themselves from exposure.

Simple safety procedures can be implemented to minimize exposure to grain dust and mold spores. When working with moldy grain, wear appropriate clothing such as long sleeves, pants, and gloves. A dust mask or respirator should also be worn to minimize inhalation risks. People who have a compromised immune system or respiratory ailments should avoid handling or working with moldy grain.

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February 17, 2010 at 8:12 am

More Questions and Answers on Moldy Grain, Mycotoxins

Q. Why is there such a within load variation for vomitoxin ppm? For example, a load can test zero ppm at one elevator and 10 ppm at another elevator.

Response: Variability stems from the fact that there is variation in the number of ears infected within a field and, on any given ear, there is variation in the number of kernels infected, and even more, kernels with similar appearance in terms of moldiness on the surface, may have different levels of internal fungal colonization and consequently variation in mycotoxin contamination. In addition, healthy-looking kernels may also be contaminated with vomitoxin.  Variability is a major issue!!  Because of this variability, sampling needs to be done correctly in order to adequately determine the level of contamination. There are always “hot spots” within the grain lot and if you sample only once or a few time and end up doing so in those “hot spots” then you’ll overestimate how contaminated the grain lot really is. Conversely,  if you totally miss the hot spots then you’ll underestimate contamination. That’s the reason why we always recommend that multiple samples be taken from multiple locations within the lot, then bulk, mix and grind the grain before analysis.

We (OSU) have not used all of the testing equipments that are out there, but most of the highly recommend ones are fairly reliable and consistent. The kits that give you quantitative estimates (1,2,3,15,38 ppm) are generally better that the semi quantitative (more than 5 ppm) or qualitative (yes/no response) kits… but it all depends on what you are using the kit for. In general, the ELISA kits (most of the kits that are out there are ELISA-based) are calibrated against the more sophisticated quantitative lab equipment, and if used correctly (incorrect  use is another potential source of variation) should provide consistent results across elevators. However, test results from one elevator to another are also subject to variation in how the samples were drawn from one elevator to another. Unless the sampling is done correctly and in the same or a similar manner among elevators, it will be impossible to tell whether the differences (0 at one elevator and 10 at another) are due to differences among the testing equipments or to poor and inconsistent sampling protocols among elevators. In fact, the best way (but probably not the most practical) to compare elevators it to send subsamples from the same bulk sample for testing at the different elevators.

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Q. For on-farm separation of mycotoxin infested corn from clean corn, would a gravity table work satisfactorily?

Response: Very moldy kernels are usually lighter than healthy, plump kernels, however, like I in the paragraph above, plump-looking kernels may also be contaminated with vomitoxin. Any method that can be used to remove moldy kernels will help to reduce the overall level of contamination of the lot… moldy kernels are always more contaminated that the most contaminated of the healthy-looking kernels.

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Q. Is there a possibility of the probe itself being a cause for some of the variability in readings? Can the mycotoxin be transferred to clean corn from a probe?

Response: Although the probe can more the mycotoxin-producing fungus around, the probe is generally not a means by with the mycotoxin itself moves from contaminated to clean corn. If the corn is indeed clean (with little or no fungus) and stored correctly, then the small amount of fungal mycelium or spore carried on the probe should not be sufficient to cause major contamination of the healthy lot.  However, on the subject of cross contamination, it is never a bad practice to clean the probe before moving between lots or loads.

Part I of mycotoxin issues can be read at http://wp.me/peijs-p9

Full podcast here:

December 31, 2009 at 7:30 am

Questions and Answers on Moldy Grain and Mycotoxins

The following article appeared in the Ohio State University Extension December 22, 2009 CORN Newsletter and was written by Pierce Paul, Katelyn Willyerd and Peter Thomison:

The 2009 corn crop is providing some challenge to grain users due to various levels of mycotoxins that are being found in individual lots of grain. According to some livestock operations and ethanol plants, levels of deoxynivalenol (vomitoxin) and zearalenone in 2009 crop are unprecedented. Grain deliveries have been rejected because of excessively high mycotoxin levels. Some ethanol plants are starting to discount grain at 3 ppm (vomitoxin), with rejection above 7 ppm. Although we’ve experienced localized problems with ear rots in Ohio in past years, the incidence and severity of ear rots and associated mycotoxins this year is more severe and widespread.

Q1. How bad was the mold and mycotoxin problem in 2009?

Abnormally cool and wet weather during and after silking provided optimal conditions for the development of Gibberalla ear rot that resulted in high levels of mycotoxins contamination of harvested grain.

The fungus Gibberella zeae causes ear rot of corn and head scab of wheat. The fungus produces mycotoxins, most notably vomitoxin (deoxynivalenol, DON) as it colonizes. In general, high levels of disease severity and moldy grain indicate high levels of toxin in susceptible varieties/hybrids. Once the crop has dried down (<20% moisture), fungal growth and vomitoxin production are reduced substantially. In harvested grain, vomitoxin is heat stable and water soluble and will survive many processing, baking and distilling procedures.

Q2. What is the impact of these ear rot mycotoxins?

The Gibberella ear rot fungus produces mycotoxins that are harmful to both humans and animals. These include deoxynivalenol (Vomitoxin) and zearalenone and T-2 toxin, all of which may cause health problems. Therefore, suspect grain should be tested for these mycotoxins by chemical analysis before being fed to animals. As a general rule do not feed any grain with 5% or more Gibberella moldy kernels. Hogs and young animals are particularly sensitive to these mycotoxins.

Sampling and testing of grain are necessary to determine that vomitoxin (deoxynivalenol or DON) is below advisory levels in products. The FDA has set the advisory levels to insure the safety of the food and feed supply. For bran, flour, and germ intended for human consumption at 1 ppm. For grain and grain by-products destined for ruminating beef and feedlot cattle older than four months and for chickens with the added recommendation that these ingredients not exceed 50% of the diet of cattle or chicken at 10 ppm. For grains and grain by-products destined for swine, and all others animals with the added recommendation that these ingredients not exceed 20% of the diet for swine and 40% of the diet for other animals set at 5 ppm.

Mycotoxins in corn are concentrated about three fold in dry distillers grains, i.e. during ethanol production, removing the starch from corn (the content of which can average about 60 percent) concentrates levels of these mycotoxins.

If growers were not aware of the moldy corn/mycotoxin problem at harvest more than likely the corn could have gone into the bin in poor conditions. If proper storage conditions were not maintained, the corn will come out of the bin in very bad, perhaps unmarketable, condition surprising the grower and affecting his bottom line significantly.

Q3. Procedures to sample grain lots for Vomitoxin.

Before pulling samples for toxin analysis, grain handlers should first protect themselves from dust and toxin exposure by wearing a mask, goggles and gloves. Careful attention to sampling, extraction and testing protocol should be followed to accurately measure vomitoxin accumulation in grain. Guidelines have been written based on research done with wheat and barley and are available at the United States Department of Agriculture Grain Inspection, Packers and Stockyards website athttp://www.gipsa.usda.gov/GIPSA/documents/GIPSA_Documents/don.pdf.

To collect a representative sample from the bin or truckload of grain, 5-10 subsamples should be randomly collected from multiple locations. Samples taken only from the central or outer portions of the load or from the beginning and end of the grain stream will not provide an accurate estimate of toxin contamination. For end-gate sampling, sample from the entire width and depth of the stream. For probe sampling, use hand or mechanical probes to sample from the entire bin, in an “X”-shaped pattern, for example. The use of suction or air probes is not recommended when sampling grain for mycotoxins. Once subsamples are obtained, bulked, and cleaned, the grain must be ground uniformly, in a clean grinding apparatus, to resemble flour. Finer particle size increases surface area of the grain and allows for more efficient extraction of vomitoxin.

Q4. How and where to test for mycotoxins?

The most common test for vomitoxin is an ELISA test, which is based on the ability of toxin in the grain to bind to specific antibodies coating the specially-designed sample cups provided with the ELISA kit. These kits are very specific for the toxin being tested (vomitoxin in this case) and will not provide estimates of other toxins in the sample. There are separate kits for each toxin. ELISA-based tests are generally qualitative, providing a yes/no answer for the presence of DON, or semi-quantitative, giving an estimate of DON above certain levels or within a given range. However, quantitative estimates can also be obtained using some ELISA-based test. A color-change will be indicative of vomitoxin presence in the sample. To quantify toxin concentration an additional step of assessing color quality through a well reader or spectrophotometer is required. There is a relationship between the intensity of color in the sample cup and vomitoxin, as determined by a standard curve included in the kit. ELISA’s are easy, quick and affordable, but must be performed carefully to ensure quantifiable and accurate results. Due to the test’s specificity, you must use an ELISA kit specifically designed to detect vomitoxin. In addition, the ELISA kit must be approved for the substrate to be tested (corn, DDGs, wheat, etc).

Individuals who to know what the status of grain lots they have in storage maybe can work with grain handlers with the test or if they want to do there own analysis they can obtain ELISA kits . GIPSA has approved several different types of test kits that use either fluorescence or enzyme linked immunosorbent assay (ELISA) technology. The commercial testmethods approved by GIPSA for official testing of barley, malted barley, corn, oats, and wheat for DON are:

Biopharm – RidaScreen Fast SC for registered users only
Charm Science – Rosa Don P/N http://www.charm.com/content/view/81/274/lang,en/
Diachemix -DON FPA http://www.diachemix.com/
Diagnostix – EZ- Quant, EZ- Tox http://www.diagnostix.ca/
Neogen- 5/5, Agriscreen, Veratox http://www.neogen.com/
Romer – Accutox, Fluoroquant http://www.romerlabs.net/
Strategic Diagnostic Inc – Myco, http://ww.sdix.com/
Vicam – Don FQ http://www.vicam.com

A listing of Laboratories who will test for deoxynivalenol or DON, T-2 which are all terms for the group of toxin of concern can be found at: http://www.oardc.ohio-state.edu/ohiofieldcropdisease/wheat/mycotoxin%20text2.htm

December 24, 2009 at 8:30 am

Mycotoxin Management in Corn

The following article was written by Bruce Clevenger and Chris Zoller, OSU Extension Educators, for the December issue of the Ohio Ag Manager:

Many corn growers across Ohio are dealing with corn that is still high in moisture and some elevators are rejecting corn because of mycotoxin levels that are not safe to feed to livestock. The most common mycotoxin being detected above critical use levels is Deoxynivalenol (vomitoxin, DON). Some farmers are reporting variations across fields and within the same fields. A combination of late planting, cool temperatures and varieties are contributing to the mold and poor grain quality.

Go to http://www.ag.purdue.edu/Documents/AgAnswers/2009_Harvest.pdf to view recommendations published by Purdue University Extension for harvesting, storing, drying, feeding and marketing wet corn. If you have additional questions, consult with your OSU Extension Educator, nutritionist, veterinarian, or crop consultant.

Internet based video presentations have been developed from Purdue University and the University of Illinois. They have been archived and can be viewed at the following addresses:

Purdue University: Managing the 2009 Harvest

http://extension.entm.purdue.edu/grainlab/index.php?page=news/home.php

University of Illinois : Wet Corn Strategies and Alternatives (feeding recommendations)

http://events.idtg.illinois.edu/wet_corn/category/wet-corn/

Full podcast here:

December 16, 2009 at 8:35 am


Notice

This blog is no longer being maintained. Information on this blog may still be relevant, but for the latest agronomic information and farm management information please visit http://corn.osu.edu and http://ohioagmanager.osu.edu, respectively.

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