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By Mary-Howell Martens, Lakeview Organic Grain
Added November 20, 2012. Mycotoxins are toxic chemicals produced by certain types of fungi that grow on plant material, both in the field or in storage. Mycotoxins are a common problem worldwide, indeed, it is estimated that globally, over 25% of field crops are affected annually with mycotoxins. In Europe, Napoleon’s defeat in Russia may not have been due as much to cold or military skill but rather to mycotoxin-contaminated grain fed to their animals which resulted in a catastrophic loss in horses.
Here in the northeast, we often are not conscious of mycotoxin-related issues, although a recent study from Vermont estimates that over a 10 year period, nearly all dairy farms in that state will experience mycotoxin-related issues, even though most will not connect symptoms to actual cause. Recent erratic weather that has caused significant crop stress has made it difficult for many of American farmers to not notice mycotoxins - serious animal health problems, poor quality forage and rejected grain has brought the issue front-and-center for many people. The severe drought in the Midwest this year has resulted in significant mycotoxin-contaminated grain that is now moving ‘through the system’ and requires dairy farmers to be ever more alert to this issue.
Many types of feedstuffs can develop fungal toxins, or mycotoxins, including grains, haylege, baleage, silage, dry hay, and high moisture corn. Infection is most common on plants grown under stress, especially when damaged by insects, birds, mites, hail, early frost, heat and drought stress, windstorms, and other unfavorable weather. Mycotoxins can also form or increase when grains and forages are harvested and stored at undesirably high moisture levels, when grains are put into storage dirty, if plastic ag bags get torn or damaged, or if storage facilities leak.
Experts estimate there are over 300 fungal toxins can contaminate crops, but several are distressingly common and damaging. In the Northeast, the common soil fungus, Fusarium, causes ear-rot in corn and scab or head blight in wheat, barley, oats, and rye and produces several mycotoxins, including vomitoxin (DON), fuminosin, and zearalenone. Fusarium can also infect ensiled/bagged forage and silage. The risk increases when corn/forage is harvested late (especially after frost), gets moldy or lodged in the field, is rained on or sours in the windrow, or is not adequately packed to exclude oxygen. Silage corn cut after a frost or late in the season is often too dry to pack well, impairing normal fermentation and allowing Fusarium, already present on the corn, to proliferate. Several species of the Aspergillus fungus produce aflatoxin, which is most commonly seen in hotter, dryer areas of the South and southern Midwest. Greenish-colored Penicillium is most commonly seen in silage and can produce several different toxins. Ergot toxins (from the mushroom fungus Claviceps) have also caused problems mostly on rye (St. Anthony’s Fire). Byproducts can also contain mycotoxins, with products containing peanuts being notorious for alfatoxin problems.
How do you know whether your grain/forage contains mycotoxins? If feed is visibly moldy, that is a pretty good clue –just as you wouldn’t eat moldy food, neither should your animals. However, it usually isn’t that simple. Not all molds you can see produce toxins, and not all grain/forage containing toxins looks moldy. For that reason, although we rarely see moldy grain, we do often test often for mycotoxins. There are accurate lab tests available – Dairy One does a nice 6 mycotoxin scan for $65, but this are expensive and slow, and tests are only as accurate and representative as the sample was, so they are usually not done unless there is good reason to suspect a problem.
What makes us suspicious? We generally test grain that is light test weight, poorly matured, off-color, musty, dusty, harvested excessively late, has many broken or damaged kernels, or just doesn’t look/smell/feel right. We also randomly test other samples of each grain during the season to get a baseline and to check our assumptions. A slight pink coloration to the grain can indicate the presence of Fusarium. We usually recommend testing all on-farm feed supplies if a farmer complains of ‘typical’ mycotoxin symptoms in their animals. We also recommend that, if you must feed forages that are moldy, slimy, off-smelling, or otherwise not quite right, you test them first. Traditionally, aflatoxins have been detected by placing grain under a ‘black light’, but that is not a reliable test for the Fusarium toxins.
At high levels, mycotoxins can cause liver damage, internal hemorrhaging, cancer, abortion, and reproductive failure in animals, but even a fairly low levels, they can strongly suppress an animal’s immune system, resulting in other opportunistic infections, such a salmonella, clostridia, and E coli to ‘break through’, causing diarrhea, mastitis, and other production/health problems. Some mycotoxins are estrogen-like, interfering with cycling, conception and fetal development.
Often before clinical symptoms are seen, feed with mycotoxins can result in reduced feed intake, impaired rumen functioning, elevated SCC, poor vaccine take, reduced milk yield and butterfat, reduced weight gain, and impaired reproductive function in both females and males. The problem here, of course, is that other factors can cause similar low-grade symptoms, which is why farmers may not connect symptoms to cause. But, if you see such symptoms, mycotoxins in feed are one of the first things to address. Animals under stress for other reasons tolerate lower levels of mycotoxins than healthy animals.
There are ‘threshold’ levels of concern for different mycotoxins depending on the animal species being fed. According Dairy One, ruminants can tolerate a total toxin level of around 5 parts per million (ppm) of vomatoxin while other experts caution not to exceed 1-2 ppm. Pigs and chickens are much more sensitive. The acceptable threshold for organic human food grains is essentially zero. Other mycotoxins are of concern at a much lower tolerance level. New York State has just issued an official warning regarding aflatoxin levels in feed, stating that, according to FDA law, feeding dairy animals grain testing over 20 parts per billion is technically illegal. One reason for this lower tolerance level is that alfatoxin can be present in the milk of a cow fed contaminated feed. For more information on New York’s recent communication on mycotoxins, please see:
It is important for livestock farmers to recognize that as far as the animal is concerned, it is the total cumulative intake level of all mycotoxin-infected feed that counts. Even if each individual feed/forage item tests ‘below threshold levels’ (including baleage, silage, grain, ground feed, high moisture corn etc), if eaten together by one animal, the overall level may exceed the threshold and adverse effects will be seen. Also, frequently contaminated feed/forage contains more than one toxin, further complicating the decision of whether you have reached a level for concern.
While there are products available to ‘bind’ or adsorb toxins, none are 100% reliable, so it is best to avoid feeding suspect feed whenever possible. If you need to use a toxin binder, try to match the correct binder to the toxin present. In the feed industry, mycotoxin binders are often termed ‘flow or anti-caking agents’ to avoid making actual efficacy claims.
Those allowed under organic standards fall into 2 primary categories - the clay (or silicate/montmorillonite)-based products (Desert Dynamin, Redmond Conditioner, bentonite etc) which are most effective against aflatoxins; and the newer lower-inclusion rate oligosaccharide/beta-glucan yeast cell-wall products (Check M, Immunowall, FloMatrix, Fuse 207, Mycotex, BioMos etc) which are much more effective against the Fusarium toxins. If you suspect a mycotoxin problem and can’t avoid using the feed/forage, the best approach would probably be to use a ‘combination’ type product (i.e. FloMatrix) or use a couple of products with different efficacy (i.e Fuse 207 + Mycotex) .
Steps to minimize mycotoxin levels in grain and feed
For more information, contact Mary-Howell Martens at firstname.lastname@example.org.
Posted: to Organic Production on Tue, Nov 20, 2012
Updated: Tue, Nov 20, 2012