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Mycotoxins

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Mycotoxins

  1. 1. MYCOTOXINS <ul><li>Dale M. Forsyth </li></ul><ul><li>Dept of Animal Sciences </li></ul><ul><li>Purdue University </li></ul>
  2. 2. MYCOTOXINS <ul><li>Toxins produced by fungi </li></ul><ul><li>Metabolic products or by-products of fungi (molds) </li></ul>
  3. 3. Why Great Concern? <ul><li>Some mycotoxins are DEADLY at very small dosages. </li></ul><ul><li>Some mycotoxins are carcinogenic. </li></ul><ul><li>Some mycotoxins cause huge losses in productivity in animals. </li></ul>
  4. 4. Most fungi do not produce Mycotoxins <ul><li>Many fungi are edible </li></ul><ul><li>Mushrooms are fungi </li></ul><ul><li>Moldy feeds may be degraded without presence of mycotoxin, or may be unaffected in value. </li></ul><ul><li>some material courtesy of Mark Diekman </li></ul>
  5. 5. DIPLODIA Infested Corn
  6. 6. Effect of fungus Damage on Digestibility of Corn by Rats (Corn essentially 100% Fungus damaged) Mitchel & Beadles, 1940
  7. 7. Feeds Most Susceptible to Fungi-producing Mycotoxins <ul><li>Corn </li></ul><ul><li>Wheat </li></ul><ul><li>Oats </li></ul><ul><li>Barley </li></ul><ul><li>Recently Sorghum </li></ul><ul><li>Cottonseed </li></ul><ul><li>Peanut meal </li></ul><ul><li>Rye </li></ul>
  8. 8. Moldy grain is usually nontoxic <ul><li>Competition between toxic and nontoxic molds. </li></ul><ul><li>Entire mold population is not producing mycotoxin </li></ul><ul><li>Conditions for growth are different for mold growth vs mycotoxin production </li></ul>
  9. 9. Molds that attack grain can: <ul><li>Decrease grade </li></ul><ul><ul><li>Kernel damage </li></ul></ul><ul><ul><li>odor </li></ul></ul><ul><li>Decrease milling quality </li></ul><ul><li>Decrease seed germination </li></ul><ul><li>Decrease dry matter </li></ul><ul><li>Decrease feeding value (sometimes) </li></ul>
  10. 10. Mycotoxins can cause: <ul><li>Death </li></ul><ul><li>Poor performance from low FI, ADG </li></ul><ul><li>Respiratory problems </li></ul><ul><li>Reproductive problems </li></ul><ul><li>Liver, kidney or other organ damage </li></ul><ul><li>Cancer </li></ul>
  11. 11. Mycotoxins Factors causing variation in effects <ul><li>Species, breed </li></ul><ul><li>Age </li></ul><ul><li>Sex </li></ul><ul><li>Nutritional status </li></ul><ul><li>Other diseases </li></ul><ul><li>Other mycotoxins </li></ul><ul><li>Extent of exposure </li></ul>
  12. 12. Some mycotoxins are formed in the field, some in storage <ul><li>Storage conditions that favor production of mycotoxins: </li></ul><ul><ul><li>Temperature (40 - 90 o F ; 4 - 32 o C) </li></ul></ul><ul><ul><li>Relative Humidity (> 70%) </li></ul></ul><ul><ul><li>Moisture (22-23% in grain) </li></ul></ul><ul><ul><li>Oxygen (1-2%) </li></ul></ul>
  13. 13. MOST COMMON MYCOTOXINS in the USA <ul><li>DEOXYNIVALENOL (vomitoxin) Fusarium </li></ul><ul><li>ZEARALENONE (Gibberella) </li></ul><ul><li>AFLATOXIN - Aspergillus flavus </li></ul><ul><li>FUMONISON - Fusarium moniliforme </li></ul><ul><li>ERGOT (ergotamine, dihydroergosine) </li></ul><ul><li>Claviceps </li></ul>
  14. 14. Trichothecene Mycotoxins <ul><li>Nivalenol </li></ul><ul><li>Deoxynivalenol </li></ul><ul><li>T-2 toxin </li></ul><ul><li>HT-2 toxin </li></ul><ul><li>Diacetoxyscirpenol </li></ul><ul><li>Triacetoxyscirpendiol </li></ul><ul><li>Fusarenone X </li></ul><ul><li>Verrucarin A, B, J </li></ul><ul><li>Roridin A, D, E, H </li></ul><ul><li>Many Others (29+) </li></ul><ul><li>These are “field” toxins, not “storage” toxins </li></ul>
  15. 15. Other Mycotoxins of Growing Interest <ul><li>Ochratoxins </li></ul><ul><ul><li>Produced by Penicillium verrucosum and several spp. Of Asperfillus. </li></ul></ul><ul><ul><li>Potently nephrotoxic and carcinogenic, teratogenic and immunotoxic. </li></ul></ul><ul><ul><li>Public health problem, but little evidence of problematic instances in swine. </li></ul></ul>
  16. 16. Other Common Molds <ul><li>Penicillium </li></ul><ul><ul><li>Common blue mold </li></ul></ul><ul><ul><li>Capable of producing mycotoxin, usually does not. </li></ul></ul><ul><li>Diplodia </li></ul><ul><ul><li>Affected cattle and sheep in Africa </li></ul></ul>
  17. 17. Organisms - 1 <ul><li>Fusarium </li></ul><ul><ul><li>Taxonomy is quite confusing </li></ul></ul><ul><ul><li>Has had classification changed various times </li></ul></ul><ul><ul><li>Fusarium roseum , Fusarium graminearum and Gibberella zeae are all terms applied to the same thing. </li></ul></ul><ul><ul><li>Gibberella zeae is the “perfect” (reproductive) stage </li></ul></ul><ul><ul><li>Nickname “GIB” corn. </li></ul></ul>
  18. 18. Fusarium toxins <ul><li>Deoxynivalenol </li></ul><ul><ul><li>Feed refusal </li></ul></ul><ul><ul><li>Emesis (so nicknamed “vomitoxin”) </li></ul></ul><ul><li>Zearalenone </li></ul><ul><ul><li>Estrogenic effects </li></ul></ul>
  19. 19. Deoxynivalenol <ul><li>Feed refusal factor for pigs. </li></ul><ul><li>Emetic (vomiting) </li></ul><ul><ul><li>but seldom see pigs vomiting, refuse feed </li></ul></ul>
  20. 20. Deoxynivalenol - Feed Refusal <ul><li>Nearly complete refusal at low dosages (~5 ppm) by swine . </li></ul><ul><li>Reduced intake and poor performance at very low dosages (~1 ppm or less) </li></ul><ul><li>Other animals much much less affected! </li></ul><ul><li>DON doesn’t account for all the refusal, other metabolites are involved (though seldom tested for). </li></ul>
  21. 21. DON Does Not affect Reproduction
  22. 22. Field conditions that favor Gib fungus <ul><li>Cool, wet weather at silking time </li></ul><ul><li>Slow drying weather at harvest </li></ul><ul><li>Varieties with tight husks </li></ul>
  23. 23. Recovery of DON-infected CORN <ul><li>DON is very stable! </li></ul><ul><ul><li>Heat, chemicals, etc. have no effect. </li></ul></ul><ul><li>DON is water soluble! </li></ul><ul><ul><li>So, can be leached out and washed away. </li></ul></ul><ul><ul><li>Not too practical, so </li></ul></ul><ul><li>Advice: feed to other animals instead. </li></ul>
  24. 24. Guidelines on Levels <ul><li>FDA guidelines on DON in feeds </li></ul><ul><ul><li>10 ppm in grains, by-products for chickens & cattle (5 ppm total ration) </li></ul></ul><ul><ul><li>5 ppm in ingredients for swine max inclusion rate 20% (1 ppm total ration) </li></ul></ul><ul><ul><li>5 ppm ingredients max inclusion 40% (2 ppm) all other animals </li></ul></ul><ul><li>Canada: 1 ppm pigs, calves, lambs, lactation. </li></ul><ul><ul><li>5 ppm adult cattle, sheep, poultry </li></ul></ul>
  25. 25. Zearalenone <ul><li>Prepuberal gilts show enlarged, swollen vulva as if in estrus </li></ul><ul><li>Interrupted reproductive cycles in female swine </li></ul><ul><li>Prolapse of the vulva possible </li></ul><ul><li>Lengthened or absent estrous cycle </li></ul><ul><li>Little or no effect on growth </li></ul>
  26. 26. Little effect of Z on growth Initial wt 10 kg, fed 4 wk. James & Smith (1982)
  27. 27. Organisims - 2 <ul><li>Aspergillus spp. - Especially A. flavus </li></ul><ul><li>Also A. parasiticus and Penicillium puberulum. </li></ul><ul><li>Soil organism ( A. flavus ), so quite common, especially in peanuts. </li></ul><ul><li>CAN produce AFLATOXIN </li></ul><ul><li>AFLATOXIN is probably the worst common mycotoxin we deal with. </li></ul>
  28. 28. AFLATOXIN <ul><li>Most references to “mycotoxin”, unspecified, refer to Aflatoxin. </li></ul><ul><ul><li>There is NO reason to assume similarities with other mycotoxins, in any regard. </li></ul></ul><ul><li>Can be deadly at low dosages </li></ul><ul><ul><li>In 1st outbreaks (~1960) 100,000 turkeys died + many ducks. </li></ul></ul><ul><ul><li>Associated with “groundnut” (peanut) meal </li></ul></ul>
  29. 29. Aflatoxin (cont) <ul><li>Occurs in corn and other grains also. </li></ul><ul><li>Temperature > 12 C (54 F) and high humidity (83% at 30 C). </li></ul><ul><ul><li>Therefore usually a bigger problem in USA in South and Southeast. </li></ul></ul><ul><li>Hepatic toxin - zonation, biliary proliferation, degeneration. </li></ul><ul><li>Carcinogenic in chronic situations. </li></ul>
  30. 30. AFLATOXIN EFFECTS <ul><li>Inhibits protein synthesis </li></ul><ul><li>Poor gain </li></ul><ul><li>Liver damage </li></ul><ul><li>Susceptibility to Infection </li></ul><ul><li>Residues / carcinogenicity </li></ul><ul><li>Reproduction in swine not primarily affected </li></ul>
  31. 31. Aflatoxin on Performance
  32. 32. Aflatoxin (cont)
  33. 33. A few of many Aflatoxins
  34. 34. Aflatoxin Detection <ul><li>Black Light test - BYG fluorescence </li></ul><ul><ul><li>Abused. Use very carefully by trained people </li></ul></ul><ul><ul><li>Presumptive test for organism, not aflatoxin </li></ul></ul><ul><ul><li>Many other things fluoresce, including broken soybean seeds </li></ul></ul><ul><li>Chromatography </li></ul><ul><ul><li>Including rapid minicolumn in-field tests </li></ul></ul>
  35. 35. Dealing with AFLATOXIN <ul><li>FDA ACTION level is 20 ppb </li></ul><ul><li>Small amount may contaminate huge quantities </li></ul><ul><li>Strategies to decontaminate must have FDA approval in USA. </li></ul><ul><li>Some methods, however, can lower aflatoxin levels. </li></ul>
  36. 36. DECONTAMINATION <ul><li>Cleaning, separation, sorting </li></ul><ul><li>AMMONIATION </li></ul><ul><li>Binding Agents </li></ul><ul><ul><li>Sodium aluminosilicate and hydrated sodium calcium aluminosislicate </li></ul></ul><ul><ul><li>NOT GRAS for binding mycotoxins. </li></ul></ul><ul><li>MUCH BETTER TO PREVENT FORMATION </li></ul>
  37. 37. Preventing Mycotoxins <ul><li>Use “clean” procedures. </li></ul><ul><li>Prevent contamination </li></ul><ul><li>Inhibit mold growth </li></ul><ul><ul><li>Drying </li></ul></ul><ul><ul><li>Refrigeration </li></ul></ul><ul><ul><li>Mold inhibitors </li></ul></ul>
  38. 38. Additional Mycotoxins
  39. 39. FUMONISON <ul><li>Deadly to horses </li></ul><ul><ul><li>equine leukoencephalomalacia </li></ul></ul><ul><li>Swine - pulmonary oedema </li></ul><ul><li>Renal toxicity and hepatotoxic </li></ul>
  40. 40. FUMONISON <ul><li>Actually 8 analogs known, only B1, B2 & B3 often found. </li></ul><ul><li>ORGANISM is Fusarium moniliforme [=F. verticillioides (Sacc.) Nirenberg] or F. proliferatum </li></ul><ul><li>Fusarium moniliforme is VERY COMMON but seldom produces mycotoxin. </li></ul>
  41. 41. Fumonison - Levels <ul><li>< 5 ppm for Horses </li></ul><ul><li>10 ppm for swine </li></ul><ul><li>50 ppm for cattle </li></ul>
  42. 42. ERGOT <ul><li>Traditionally, this is a disease of RYE and other small grains. </li></ul><ul><li>New threat in Grain Sorghum (milo) to Western Hemisphere. </li></ul><ul><ul><li>Has been prevalent in Africa for decades (claviceps africana) </li></ul></ul><ul><ul><li>Has very rapidly spread in last 2 years, now in USA. </li></ul></ul>
  43. 43. Sorghum Ergot <ul><li>Pathogen causes ovary to exude a sticky liquid. </li></ul><ul><li>Dihydroergosine at .6 ppm decreases FI & ADG. </li></ul><ul><li>Effect appears to be from poor feed intake </li></ul><ul><ul><li>Dean et al, 1999 </li></ul></ul>
  44. 44. Traditional Ergot <ul><li>Claviceps purpurea produces ergotamine and other alkaloids. </li></ul><ul><ul><li>Psychoactive - convulsions, hallucinations, abortions </li></ul></ul><ul><ul><li>Paralysis, GI disturbance, gangrene of extremities, death. </li></ul></ul>
  45. 45. ADVICE <ul><li>Avoidance of Mycotoxin formation is best in every case </li></ul><ul><li>Some procedures for decontamination exist (ammonia, HSCAS), but are different for different mycotoxins, may be ineffective and may not be legal. </li></ul>
  46. 46. Advice- continued <ul><li>I would : </li></ul><ul><ul><li>Feed NO moldy feeds to reproducing animals. </li></ul></ul><ul><ul><li>Feed a small test amount to growers but DO NOT encourage consumption. </li></ul></ul><ul><ul><li>If no ill effect is observed in test, then dilute the suspect feed and incorporate small amount into normal diet. </li></ul></ul>
  47. 47. WWW References to References <ul><li>Australian Mycotoxin Newsletter </li></ul><ul><ul><li>http://www.aciar.gov.au/aciarptp/myconews.htm </li></ul></ul><ul><li>Third Joint FAO/WHO UNEP International Conference on Mycotoxins, Mar 1999 </li></ul><ul><ul><li>http://www.fao.org/WAICENT/FAOINFO/ECONOMICS/ESN/mycoto/papers/ </li></ul></ul>

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