Introduction
Safe Levels of Mycotoxins
Available Mycotoxin Data
Mycotoxins and Animal Health
Effects of Mycotoxins on the Health and
Productivity of Specific Production
Animals
Prior to giving specific information, some general concepts regarding the effect of mycotoxins on animals must be understood. The determination as to whether or not a given concentration of mycotoxin is safe will depend on at least the factors which follow (and there may also be other factors).
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Table 1. A Partial List of Known Mycotoxins Aflatoxins Fusaric Acid Penicillic Acid Alternariol Fusariocin Penitrem Citreoviridin Fusarins Phomopsin Citrinin Islanditoxin Roridins Cyclopiazonic Acid Luteoskyrin Rubratoxin Deoxynivalenol Moniliformin Slaframine Diacetoxyscirpenol Monoacetoxyscirpenol Sporidesmin Dicoumarol Neosolaniol Stachbotryotoxins Ergotamine Ochratoxins Sterigmatocystin Ergo Toxins Oosporein T-2 Toxin Fumitremorgen Paspalitrems Tremorgens Fumonisins Patulin Zearalenone
Deoxynivalenol (DON), zearalenone, T-2 toxin, and fumonisin are all produced by molds of the genus Fusarium. Molds in this genus are found in virtually every lot of corn and collectively are capable of producing 70 different mycotoxins. Some strains of Fusarium may produce as many as 17 mycotoxins simultaneously. Thus Fusarium mycotoxins are the most frequently identified group of mycotoxins in grains and feeds.
Better control of mycotoxins will position producers for greater competitiveness and profitability. In addition, control of mycotoxins in animal diets would reduce the likelihood that mycotoxin residues would appear in animal products destined for human consumption.
Table 2. NCSU Mycotoxin Laboratory Analyses Obtained From Suspect North Carolina Feeds, Feed Ingredients, and Forages Collected From 1989 Through 1993.Click here to return to the Table of Contents.
Aflatoxin DON Fumonisin* n Av %P n Av %P n %P
MIXED FEEDS 1989-1993 342 116 11.4 572 1169 67.5 222 28.4 1989 38 46 34.2 61 2727 62.3 0 - 1990 40 358 22.5 107 802 73.8 0 - 1991 46 34 8.7 116 511 62.1 0 - 1992 77 24 2.6 94 643 48.9 85 23.5 1993 141 48 7.8 194 1443 77.8 137 31.4 TMR 28 48 17.8 44 1379 61.4 12 25.0 Forages 56 57 8.9 177 1671 66.1 54 26.4 Concentrates 257 138 11.3 350 903 69.1 156 29.5 Corn Grain 52 346 17.3 63 599 63.5 33 60.6 Soybean Meal 11 30 9.1 14 220 57.1 6 0 Cottonseed 39 135 5.1 52 2679 46.2 26 3.8 Corn Silage 36 66 11.1 106 1847 75.5 33 39.4 Grass Hay 4 - 0 26 1110 42.3 9 0 Small Grain & Grass Silage 13 - 0 36 1568 61.1 9 11.1
T-2 Toxin Zearalenone n Av %P n Av %P
MIXED FEEDS 1989-1993 430 364 4.2 538 397 18.0 1989 41 151 7.3 62 552 27.4 1990 47 2456 2.1 86 524 18.6 1991 62 - 0 104 375 2.9 1992 86 - 0 91 108 1.1 1993 194 132 7.2 195 325 30.8 TMR 36 - 0 43 237 30.2 Forages 118 290 2.5 169 379 24.8 Concentrates 275 379 5.5 325 464 12.9 Corn Grain 58 1603 3.4 57 294 5.3 Soybean Meal 12 87 16.7 13 113 46.1 Cottonseed 41 274 4.9 50 292 6.0 Corn Silage 69 60 2.9 93 445 32.3 Grass Hay 19 - 0 29 114 13.8 Small Grain & Grass Silage 26 750 3.8 36 283 19.4
NOTE: 586 samples were tested. 2104 individual mycotoxin tests were performed. 73.2% of samples were positive for at least one mycotoxin. 61% of samples were positive for aflatoxin and one other mycotoxin. 28.7% of samples were positive for all individual mycotoxin tested. n = Number of Assays. Av = Average concentration (ppb) in positive samples. %P = Percentage (of samples) Positive. Note: Percentages are based on the following levels--Aflatoxin >20 ppb, DON >40 ppb, Fumonisin >5,000 ppb, T-2 Toxin >50 ppb, Zearalenone >70 ppb. TMR = Total Mixed Ration for ruminants includes the concentrates and forages which make up the animals' total diet. *Concentration was not determined on Fumonisin samples.
Mycotoxins produce a wide range of harmful effects in animals. The economic impact of reduced animal productivity, increased incidence of disease due to immunosuppression, damage to vital organs, and interferences with reproductive capacity is many times greater than the impact caused by death due to mycotoxin poisoning. In comparison to other animals, poultry species tend to be resistant to the effects of fumonisin, deoxynivalenol, and zearalenone. However, the presence of these mycotoxins within poultry rations is an indication that mold activity has occurred in the ration or in the ingredients within the ration. Since mold activity can generate numerous other mycotoxins as well as reduce the nutritive value and palatability of feeds, the presence of fumonisin, deoxynivalenol, or zearalenone in poultry feeds is cause for concern.
While young animals are most susceptible to the effects of aflatoxin, all ages are affected; and clinical signs include gastrointestinal dysfunction, reduced productivity, decreased feed utilization and efficiency, anemia, and jaundice. Nursing animals may be affected by exposure to aflatoxin metabolites secreted in the milk. Aflatoxin causes a variety of symptoms depending on the animal species. However, in all animals, aflatoxin can cause liver damage, decreased reproductive performance, reduced milk or egg production, embryonic death, teratogenicity (birth defects), tumors, and suppressed immune system function, even when low levels are consumed.
Deoxynivalenol (DON) is, perhaps, the most commonly detected Fusarium mycotoxin. DON has been associated with reduced milk production in dairy cattle, vomiting by swine consuming contaminated feed or their refusal to eat feed containing the toxin, and inhibiting reproductive performance and immune function in several animal species. In addition, DON levels greater than 500 ppb have been associated with numerous other field problems.
Zearalenone mimics the effect of the female hormone estrogen and, at low doses, increases the size or early maturity of mammary glands and reproductive organs. At higher doses zearalenone interferes with conception, ovulation, implantation, fetal development, and the viability of newborn animals.
T-2 toxin and its chemical relatives cause irritation, hemorrhage, and necrosis throughout the digestive tract, depress the regenerative process in the bone marrow and spleen, impair immune system function, and cause changes in reproductive organs. Affected animals show signs of weight loss, poor feed utilization, lack of appetite, vomiting, bloody diarrhea, abortion, and (in severe cases) death.
Fumonisin is a mycotoxin which has only recently been discovered. Thus it has not been extensively studied. Nonetheless, it is known that in most animals fumonisin impairs immune function, causes liver and kidney damage, decreases weight gains, and increases mortality rates. Fumonisin also causes leukoencephalomalacia in horses and respiratory difficulties in swine. In some animals fumonisin can also cause tumors. Click here to return to the Table of Contents.
Aflatoxin B1 has been the most extensively studied. Twenty to 200 ppb will cause a decrease in feed intake and growth performance, which can be partially offset by increasing specific dietary nutrients such as lysine or methionine. In severe cases (1,000 to 5,000 ppb) of aflatoxicosis, one can expect acute effects including death. Aflatoxin M1 appears in milk of sows consuming aflatoxin-contaminated diets and may affect piglets nursing those sows.
Feed concentrations of deoxynivalenol (DON) of 300 to 500 ppb are often associated with feed refusal, decreased weight gain, and increased incidence of infectious diseases. DON levels greater than 1000 ppb, will cause feed refusal or decrease in feed intake resulting in severe weight loss. It appears that pigs will often consume a sufficient amount of contaminated feed to induce vomiting. In fact, DON is also called vomitoxin because of its association with swine vomiting.
T-2 toxin has detrimental effects on swine performance, but no effect levels have not been determined for commercial production environments. However, field observations indicated that T-2 and related compounds are associated with decreased productivity at feed concentrations of 200 ppb or less.
Zearalenone will significantly affect the reproductive performance of swine. Prepuberal gilts are the most sensitive to zearalenone. The symptoms commonly observed when feeding diets contaminated with zearalenone include a reddening and increased size of the vulva, and increased size of mammary tissue. Zearalenone will cause embryonic mortality at certain stages of gestation. Fertility problems are often associated with zearalenone concentrations of 100 to 200 ppb in sow feeds.
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Table 3. Maximum Mycotoxin Levels for Swine
Maximum Dietary Concentration
Deoxynivalenol Zearalenone Aflatoxin Swine Type ppb ppb ppb
Pigs <75 lb <300 200 20 Pigs 75 to 125 lb <300 200 50 Pigs 125 lb to market <300 200 100 Sow Herd <300 100 50 Breeding Males <300 100 50 These levels are based on extensive field observations. Heat stress, marginal nutrient plane, crowding, disease exposure, the presence of more than one mycotoxin, and drug interactions, as well other factors, increase animals' susceptibility to mycotoxins. Thus these recommendations must be tempered with knowledge of the animals involved.
Laying hens generally can tolerate higher levels than young birds, but levels should still be less than 50 ppb. Aflatoxin contamination can reduce the birds' ability to withstand stress by inhibiting the immune system. This malfunction can reduce egg size and possibly lower egg production. In addition, one must pay special attention to the use of contaminated corn in layer rations because eggs are promptly used as human food and aflatoxin metabolites have been found in egg yolks.
Mycotoxin levels found in most field situations tend to be low. Yet the combination of low levels of mycotoxins with the stresses associated with commercial production situations and/or exposure to disease organisms can produce effects in poultry which are subtle, indirect, and sometimes ill-defined. Since the effects of mycotoxins on poultry are dependant upon the age, physiological state, and nutritional status of the animals at the time of exposure, and since mold growth at various points within the feed production and distribution system can magnify mycotoxin problems, mycotoxicoses can be difficult to diagnose in field situations.
Mycotoxins produced by the mold genus Fusarium include: T-2 toxin and it's chemical relatives (trichothecenes), deoxynivalenol (DON), fumonisin, and zearalenone. Other animals tend to be more sensitive to the effects of fumonisin, deoxynivalenol, and zearalenone when compared to poultry. Nevertheless, detection of these mycotoxins within poultry rations indicates that the ration or the ingredients within the ration have been subjected to mold activity. Since numerous other mycotoxins, as well as reduced nutritive value and palatability of feeds, are generated by mold activity, the presence of fumonisin, deoxynivalenol, or zearalenone in poultry feeds is cause for concern.
T-2 toxin and trichothecenes can cause mouth and intestinal lesions as well as impair the birds' immune response, causing egg production declines, decreased feed consumption, weight loss, and altered feather patterns. While much is yet to be learned, T-2 toxin and related compounds are currently thought to be the most potent Fusarium mycotoxin for poultry.
DON alone has few effects in poultry. However, in field situations the DON level is sometimes associated with reduced feed consumption in layers and broiler breeders. This means that DON may be an indicator that T-2 or other unknown Fusarium mycotoxins are present. Click here to return to the Table of Contents.
Horses are herbivores with a simple stomach (nonruminant). The large intestine has an active microbial digestive ability to allow digestion of forages. However, in the horse the small intestine, which is the major site of absorption, occurs before the fermentative digestion. As a result, horses are more susceptible to mycotoxins than ruminants, since nutrient absorption occurs prior to fermentative digestion in the horse compared to ruminants in which absorption occurs after fermentative digestion.
Productive or working horses have a high energy requirement and require a higher concentrate intake, and thus would be most susceptible to problems with mycotoxin-contaminated grains. Working horses would include growing horses less than two years of age, brood mares in late gestation and early lactation, and horses at moderate or intense work levels.
Other horses, that are only lightly worked, would be more likely to be exposed to mycotoxin-contaminated hays or forages. Since moldy forages are generally less palatable than normal forage, horses fed moldy forages typically refuse feed before ingesting enough feed to cause severe intestinal tract damage. Mild colic is typically noted in such cases. Unfortunately, most molds associated with grains fed to horses do not readily affect palatability. Consequently, horses are most often exposed to the mycotoxins found in grains. Grain mycotoxins are readily absorbed and should be considered to be potentially lethal for horses.
If mycotoxin-contaminated feeds must be fed, follow these guidelines:
Additional research is needed to clarify the effects of mycotoxins on horses. Until such data exist, caution should be taken to select and feed mold-free grains and forages. Click here to return to the Table of Contents.
Table 4. Maximum Mycotoxin Levels for Mature, Nonbreeding Horses
MYCOTOXIN LEVEL
Aflatoxin 50 ppb T-2 Toxin 50 ppb DON 400 ppb Zearalenone 100 ppb Fumonisin 2,000 ppb Note: The above levels are based on field observations. Controlled scientific studies are needed to clarify specific mycotoxin tolerance and toxicity levels. Heat stress, marginal nutrient plane, crowding, disease exposure, the presence of more than one mycotoxin, and drug interactions, as well other factors, increase animals' susceptibility to mycotoxins. Thus these recommendations must be tempered with knowledge of the animals involved.
In dairy cattle DON is associated with reduced feed intake, lower milk production, elevated milk somatic cell counts, and reduced reproductive efficiency. Milk production loss appears to occur when diets contain more than 300 ppb DON. Although controlled research has shown no cause and effect relationship between DON levels and reduced milk production, field observations have shown that reductions in milk output of 25 pounds per cow were seen when DON was 500 ppb or more. This suggests that DON may serve as a marker for feed that was exposed to a situation conducive to mold growth and mycotoxin formation. The possible presence of other mycotoxins, or factors more toxic than DON, seems likely. Dietary levels of 300 to 500 ppb DON in dairy feeds indicate mycotoxin problems and warrant attention.
Zearalenone causes estrogenic responses in dairy cattle, and large doses of this toxin are associated with abortions. Other responses of dairy animals to zearalenone may include reduced feed intake, decreased milk production, vaginitis, vaginal secretions, poor reproductive performance, and mammary gland enlargement in virgin heifers. Establishment of a tolerable level of zearalenone for dairy cattle is difficult, and is at best only a guess based on a meager amount of data and field observations. As with DON, zearalenone may serve as a marker for toxic feed. It is suggested that zearalenone not exceed 250 ppb in the total diet.
In dairy cattle T-2 toxin has been associated with feed refusal, production losses, gastroenteritis, intestinal hemorrhages, and death. T-2 has also been associated with reduced immune response in calves. Data with dairy cattle are not sufficient to establish a tolerable level of T-2 in the diet. Therefore, a practical recommendation may be to avoid T-2 in excess of 100 ppb in the total diet for growing or lactating dairy animals.
Fumonisin is another commonly isolated mycotoxin. However, fumonisin has only recently been isolated and only enough data exist to know that levels in excess of 20,000 ppb are potentially toxic to ruminants. Click here to return to the Table of Contents.
Based on the feeds available, those contaminated with aflatoxin should be fed at the lowest level possible and for the shortest period of time practical. The effects of aflatoxin fed to cattle depend on the level of aflatoxin in the ration, the length of the feeding period, and the age of the animal. If aflatoxin-contaminated feeds must be fed to beef cattle, follow these guidelines (on a dry matter basis):
Other mycotoxins (DON, T-2, and zearalenone) present in grains, silages, and hays may cause problems with performance and immune status of beef cattle. However, little research is available on the levels of the individual toxins that may be tolerated by animals. In cases of disease outbreaks and reproductive problems, the feed should be tested for a full range of mycotoxins. Large producers should consider routinely screening feeds for mycotoxins.
Table 5. Allowable Aflatoxin in Grain for Beef Cattle
Percentage of Grain Aflatoxin Level in Total Diet in Diet 20 ppb 50 ppb 100 ppb
20% 100 ppb 250 ppb 500 ppb 40% 50 ppb 125 ppb 250 ppb 60% 33 ppb 83 ppb 167 ppb 80% 25 ppb 63 ppb 125 ppb This table assumes that aflatoxin is contained only in grains. This assumption is not always correct. Each dietary component should be tested for aflatoxin prior to use of any contaminated grains. Heat stress, marginal nutrient plane, crowding, disease exposure, the presence of more than one mycotoxin, and drug interactions, as well other factors, increase animals' susceptibility to mycotoxins. Thus these recommendations must be tempered with knowledge of the animals involved.
Until further information is available, the producer should limit dietary mycotoxins to the levels listed (Table 6).
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Table 6. Maximum Mycotoxin Levels for Beef Cattle
MYCOTOXIN LEVEL
DON 500 ppb T-2 100 ppb Zearalenone 250 ppb Fumonisin 50,000 ppb Heat stress, marginal nutrient plane, crowding, disease exposure, the presence of more than one mycotoxin, and drug interactions, as well other factors, increase animals' susceptibility to mycotoxins. Thus these recommendations must be tempered with knowledge of the animals involved.
Silo size should be matched to herd size to ensure daily removal of silage at a rate faster than deterioration. Feed bunks should be cleaned regularly. Care should be taken to ensure that high moisture grains are stored at proper moisture content and in a well-maintained structure. Click here to return to the Table of Contents.
It is commonly believed that the amount of moisture in grain is too small to permit mold growth except in rare and unusual circumstances. However, moisture is not evenly distributed in grain kernels. A batch of grain containing an average of 15.5 percent moisture may, for example, contain some kernels with 10 percent moisture and others with 20 percent moisture. The moisture content of individual grain kernels is directly related to the amount of mold growth that occurs: that is, kernels with higher moisture contents were more susceptible to mold growth. In addition to moisture, the amount of mold growth is about five times greater for broken kernels than for intact kernels. Thus the fraction of commercial grain, known as broken kernels and foreign matter, can be expected to have a higher mold and mycotoxin content than the portion composed of whole kernels.
The pelleting process involves mixing steam with the feed, pressing the mixture through a die, and then cooling the pellets to remove heat and moisture. Generally, heat and 3 to 5 percent moisture are added to the feed during the pelleting process in the form of steam. If the pelleting process is done correctly, this excess moisture is removed from the feed before shipment. If, however, this excess moisture is not removed when the pellets are cooled, mold growth will be encouraged. Since feeds containing moisture are warmer than normal, storing hot or warm pellets in a cool bin will cause moisture to condense on the inside of the bin.
Although pelleting of feed has been shown to reduce mold counts by a factor of 100 to 10,000, many mold spores remain in the feed after it has been pelleted. After pelleting, the remaining spores can grow if conditions are right. Thus the pelleting process delays, but does not prevent, the onset of mold growth and plays only a minor role in efforts to control molds. In addition, pelleted feeds may be more easily attacked by molds than nonpelleted feeds.
A fact about feed moisture often overlooked is that it changes in relation to the feed's environment. Since animals kept in confinement housing add moisture to their environment by respiration and defecation, the air in these houses can be very humid. Feed that was initially very low in moisture content will gain moisture when placed in a humid environment. The humidity in confinement housing should therefore be controlled by providing adequate ventilation. Click here to return to the Table of Contents.
It is equally important to manage the feed delivery system to ensure that feeds are uniform in freshness. Field surveys have shown that poultry farms producing birds with the poorest performance were those with the most feed in their feeder pans. On these farms, the feeds contained the greatest amount of moisture and had the highest number of molds. If the feeder system is allowed to keep the feed pans full at all times, the feed in the pans will be significantly older than that in the storage tank. The animals will tend to eat primarily the feed in the top layer, and the feed at the bottom of the pans will age, providing greater opportunities for molds to grow. The animals' performance may suffer as a result. To prevent this problem, the feeder system should be turned off weekly. The animals will then be forced to clean out all of the feed in the feeders before it becomes excessively old.
A similar principle applies to feed storage tanks. The feed next to the wall is last to exit the tank and therefore stays in the tank the longest. The feed in contact with the wall is also the only portion of the feed that changes appreciably due to temperature. These factors make feed in contact with the wall susceptible to moisture migration and mold growth. It is best to maintain two feed tanks so that one tank can be completely emptied and cleaned before it is refilled with new feed. Click here to return to the Table of Contents.
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The main types of mold inhibitors are (1) individual or combinations of organic acids (for example, propionic, sorbic, benzoic, and acetic acids), (2) salts of organic acids (for example, calcium propionate and potassium sorbate), and (3) copper sulfate. Solid or liquid forms work equally well if the inhibitor is evenly dispersed through the feed. Generally, the acid form of a mold inhibitor is more active than its corresponding salt.
The particle size of the carriers for mold-inhibiting chemicals should be small so that as many particles of feed as possible are contacted. In general, the smaller the inhibitor particles the greater the effectiveness. Some propionic acid inhibitors rely on the liberation of the chemical in the form of a gas or vapor from fairly large particle carriers. Presumably, the inhibitor then penetrates the air spaces between particles of feed to achieve even dispersion.
The possible use of inorganic binders (mineral clays) to bind mycotoxins, and prevent them from being absorbed by the animal's gut, has received a lot of research attention recently. These clay products (which include zeolites, bentonite, bleaching clays from refining of canola oil, and hydrated sodium calcium aluminosilicates [HSCAS]) have been shown to change the responses of rats to zearalenone and T-2 toxin. However, it should be clearly understood that binding of some mycotoxins may be weak or nonexistent and that clay products differ in their ability to bind mycotoxins. While one HSCAS product called NovaSil has been shown to bind aflatoxin protecting animals against aflatoxicosis, under FDA regulations these clay products cannot be sold as mycotoxin binders. Nonetheless, many clay products are GRAS (Generally Recognized As Safe) and are used as anticaking or free-flow additives for feeds. Click here to return to the Table of Contents.
For whole kernel grains, a properly taken composite sample of at least ten pounds is required for a reasonably accurate, mycotoxin analysis. Trucks can usually be sampled with a grain probe, but bins must often be sampled as grain is being withdrawn.
Analytical techniques for the detection of mycotoxins continue to improve. Several commercial laboratories now test for a variety of mycotoxins. Although analytical costs can be a constraint, these costs may be insignificant compared with the economic consequences of production and health losses associated with mycotoxin contamination.
Commercial antibody test kits for screening or quantitation are currently available for aflatoxins, zearalenone, deoxynivalenol (DON), T-2 toxin, ochratoxin A, and fumonisins. These antibody methods, while they are still being improved, are good if used properly. The mycotoxin test kits in Table 7 have been tested and found to perform in a wide variety of laboratories.
Screening of corn for possible aflatoxin contamination using a "black light" was a popular technique 15 to 20 years ago. In spite of the widespread use of black lighting to screen for aflatoxin and other mycotoxins, research has shown that the technique detects materials which are not mycotoxins, and is, therefore, inappropriate. The black light test should never be used for any kind of mycotoxin screening.
The minicolumn is a small column containing silica gel and Florisil (or other adsorbents) to which sample extracts are applied for detection of aflatoxin. Minicolumns were also very popular for aflatoxin screening until antibody-based test kits became widely available over the last few years. If properly used, the minicolumn test is capable of giving good results for aflatoxin under certain conditions. However, like the black light, it has often been mishandled and misused. The minicolumn is no longer recommended.
Better yet, because little is known about the above mycotoxins, and because many unidentified mycotoxins exist, cattle producers should avoid feeding moldy feeds if at all possible.
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Table 7. Some of the Commercially Available Mycotoxin Test Kits
MANUFACTURER MYCOTOXINS DETECTED TEST KIT NAME
Editek Aflatoxin EZ-Screen P. O. Box 908 Ochratoxin 1238 Anthony Rd. T-2 Toxin Burlington, NC 27215 Zearalenone Phone: (910) 226-6311 Fax: (910) 229-4471 International Diagnostic Aflatoxin(4 Kits) 1. Afla 20 Cup System Corp. 2. Afla 10 Cup 2620 S. Cleveland Ave. 3. Afla 5 Cup Suite 100 4. Afla B1, St. Joseph, MI 49085 ELISA Test Phone: (616) 428-8400 Fax: (616) 428-0093 Zearalenone (2 Kits) 1. One Step ELISA, Quantitative Test 2. I. D. Block, ELISA Antibody Neogen Corporation Aflatoxin AgriScreen 620 Lesher Place T-2 Toxin Veratox Lansing, MI 48912 Vomitoxin (DON) Phone: (517) 372-9200 Zearalenone 800) 234-5333 Fumonisin Fax: (517) 372-2006 Aflatoxin M1 Ochratoxin VICAM Aflatoxin Aflatest-P 313 Pleasant St Fumonisin Fumonitest Watertown, MA 02172 Ochratoxin Ochratest Phone: (800) 338-4381 Zearalenone Zearalatest (617) 926-7045 Fax: (617) 923-8055 NOTE: Absolute detection limits of mycotoxin test kits will vary and should be examined in relation to the needs of the user.
Anonymous. 1989. Mycotoxins economic and health risks. Council for Agricultural Science and Technology, 250 Memorial Union, Ames, IA 50011, Report No. 116, pp 91.
Bray, G. A. and D. H. Ryan, eds. 1991. Mycotoxins, cancer, and health. Pennington Center Nutrition Series, Vol. 1, Louisiana State University Press, Baton Rouge, LA, pp 331.
Coelho, M. B. 1990. Molds, mycotoxins and feed preservatives in the feed industry. BASF Corporation, 100 Cherry Hill Road, Parsippany, NJ 07054, pp 159.
Robens, J. F. ed. 1990. A perspective on aflatoxins in field crops and animal food products in the United States: A symposium. U.S. Department of Agriculture, Agricultural Research Service publication number ARS-83, pp 157.
Shimoda, W. 1979. Conference on mycotoxins in animal feeds and grains related to animal health. U.S. Department of Commerce. National Technical Information Service document number PB-300, pp 373.
Frank T. Jones, Editor, Extension Poultry Science Specialist
Mary Beth Genter, Extension Toxicology Specialist
Winston M. Hagler, Director of NCSU Mycotoxin Laboratory
Jeff A. Hansen, Extension Animal Science Specialist
Bob A. Mowrey, Extension Animal Science Specialist
Matt H. Poore, Extension Animal Science Specialist
Lon W. Whitlow, Extension Animal Science Specialist
This publication has been issued in print by the North
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This file is one in a series of electronically available
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