Presentation on theme: "MYCOTOXINS zDale M. Forsyth zDept of Animal Sciences zPurdue University."— Presentation transcript:
MYCOTOXINS zDale M. Forsyth zDept of Animal Sciences zPurdue University
MYCOTOXINS zToxins produced by fungi zMetabolic products or by-products of fungi (molds)
Why Great Concern? zSome mycotoxins are DEADLY at very small dosages. zSome mycotoxins are carcinogenic. zSome mycotoxins cause huge losses in productivity in animals.
Most fungi do not produce Mycotoxins zMany fungi are edible zMushrooms are fungi zMoldy feeds may be degraded without presence of mycotoxin, or may be unaffected in value. zsome material courtesy of Mark Diekman
DIPLODIA Infested Corn
Effect of fungus Damage on Digestibility of Corn by Rats (Corn essentially 100% Fungus damaged) Mitchel & Beadles, 1940
Feeds Most Susceptible to Fungi-producing Mycotoxins zCorn zWheat zOats zBarley zRecently Sorghum zCottonseed zPeanut meal zRye
Moldy grain is usually nontoxic zCompetition between toxic and nontoxic molds. zEntire mold population is not producing mycotoxin zConditions for growth are different for mold growth vs mycotoxin production
Mycotoxins can cause: zDeath zPoor performance from low FI, ADG zRespiratory problems zReproductive problems zLiver, kidney or other organ damage zCancer
Mycotoxins Factors causing variation in effects zSpecies, breed zAge zSex zNutritional status zOther diseases zOther mycotoxins zExtent of exposure
Some mycotoxins are formed in the field, some in storage zStorage conditions that favor production of mycotoxins: yTemperature ( o F ; o C) yRelative Humidity (> 70%) yMoisture (22-23% in grain) yOxygen (1-2%)
MOST COMMON MYCOTOXINS in the USA zDEOXYNIVALENOL (vomitoxin) Fusarium zZEARALENONE (Gibberella) zAFLATOXIN - Aspergillus flavus zFUMONISON - Fusarium moniliforme zERGOT (ergotamine, dihydroergosine) Claviceps
Trichothecene Mycotoxins zNivalenol zDeoxynivalenol zT-2 toxin zHT-2 toxin zDiacetoxyscirpenol zTriacetoxyscirpendiol zFusarenone X zVerrucarin A, B, J zRoridin A, D, E, H zMany Others (29+) zThese are “field” toxins, not “storage” toxins
Other Mycotoxins of Growing Interest zOchratoxins yProduced by Penicillium verrucosum and several spp. Of Asperfillus. yPotently nephrotoxic and carcinogenic, teratogenic and immunotoxic. yPublic health problem, but little evidence of problematic instances in swine.
Other Common Molds zPenicillium yCommon blue mold yCapable of producing mycotoxin, usually does not. zDiplodia yAffected cattle and sheep in Africa
Organisms - 1 zFusarium yTaxonomy is quite confusing yHas had classification changed various times yFusarium roseum, Fusarium graminearum and Gibberella zeae are all terms applied to the same thing. yGibberella zeae is the “perfect” (reproductive) stage yNickname “GIB” corn.
Deoxynivalenol zFeed refusal factor for pigs. zEmetic (vomiting) ybut seldom see pigs vomiting, refuse feed
Deoxynivalenol - Feed Refusal zNearly complete refusal at low dosages (~5 ppm) by swine. zReduced intake and poor performance at very low dosages (~1 ppm or less) zOther animals much much less affected! zDON doesn’t account for all the refusal, other metabolites are involved (though seldom tested for).
DON Does Not affect Reproduction
Field conditions that favor Gib fungus zCool, wet weather at silking time zSlow drying weather at harvest zVarieties with tight husks
Recovery of DON-infected CORN zDON is very stable! yHeat, chemicals, etc. have no effect. zDON is water soluble! ySo, can be leached out and washed away. yNot too practical, so zAdvice: feed to other animals instead.
Guidelines on Levels zFDA guidelines on DON in feeds y10 ppm in grains, by-products for chickens & cattle (5 ppm total ration) y5 ppm in ingredients for swine max inclusion rate 20% (1 ppm total ration) y5 ppm ingredients max inclusion 40% (2 ppm) all other animals zCanada: 1 ppm pigs, calves, lambs, lactation. y5 ppm adult cattle, sheep, poultry
Zearalenone zPrepuberal gilts show enlarged, swollen vulva as if in estrus zInterrupted reproductive cycles in female swine zProlapse of the vulva possible zLengthened or absent estrous cycle zLittle or no effect on growth
Little effect of Z on growth Initial wt 10 kg, fed 4 wk. James & Smith (1982)
Organisims - 2 zAspergillus spp. - Especially A. flavus zAlso A. parasiticus and Penicillium puberulum. zSoil organism (A. flavus), so quite common, especially in peanuts. zCAN produce AFLATOXIN zAFLATOXIN is probably the worst common mycotoxin we deal with.
AFLATOXIN zMost references to “mycotoxin”, unspecified, refer to Aflatoxin. yThere is NO reason to assume similarities with other mycotoxins, in any regard. zCan be deadly at low dosages yIn 1st outbreaks (~1960) 100,000 turkeys died + many ducks. yAssociated with “groundnut” (peanut) meal
Aflatoxin (cont) zOccurs in corn and other grains also. zTemperature > 12 C (54 F) and high humidity (83% at 30 C). yTherefore usually a bigger problem in USA in South and Southeast. zHepatic toxin - zonation, biliary proliferation, degeneration. zCarcinogenic in chronic situations.
AFLATOXIN EFFECTS zInhibits protein synthesis zPoor gain zLiver damage zSusceptibility to Infection zResidues / carcinogenicity zReproduction in swine not primarily affected
Aflatoxin on Performance
A few of many Aflatoxins
Aflatoxin Detection zBlack Light test - BYG fluorescence yAbused. Use very carefully by trained people yPresumptive test for organism, not aflatoxin yMany other things fluoresce, including broken soybean seeds zChromatography yIncluding rapid minicolumn in-field tests
Dealing with AFLATOXIN zFDA ACTION level is 20 ppb zSmall amount may contaminate huge quantities zStrategies to decontaminate must have FDA approval in USA. zSome methods, however, can lower aflatoxin levels.
DECONTAMINATION zCleaning, separation, sorting zAMMONIATION zBinding Agents ySodium aluminosilicate and hydrated sodium calcium aluminosislicate yNOT GRAS for binding mycotoxins. zMUCH BETTER TO PREVENT FORMATION
FUMONISON zDeadly to horses yequine leukoencephalomalacia zSwine - pulmonary oedema zRenal toxicity and hepatotoxic
FUMONISON zActually 8 analogs known, only B1, B2 & B3 often found. zORGANISM is Fusarium moniliforme [=F. verticillioides (Sacc.) Nirenberg] or F. proliferatum zFusarium moniliforme is VERY COMMON but seldom produces mycotoxin.
Fumonison - Levels z< 5 ppm for Horses z10 ppm for swine z50 ppm for cattle
ERGOT zTraditionally, this is a disease of RYE and other small grains. zNew threat in Grain Sorghum (milo) to Western Hemisphere. yHas been prevalent in Africa for decades (claviceps africana) yHas very rapidly spread in last 2 years, now in USA.
Sorghum Ergot zPathogen causes ovary to exude a sticky liquid. zDihydroergosine at.6 ppm decreases FI & ADG. zEffect appears to be from poor feed intake yDean et al, 1999
Traditional Ergot zClaviceps purpurea produces ergotamine and other alkaloids. yPsychoactive - convulsions, hallucinations, abortions yParalysis, GI disturbance, gangrene of extremities, death.
ADVICE zAvoidance of Mycotoxin formation is best in every case zSome procedures for decontamination exist (ammonia, HSCAS), but are different for different mycotoxins, may be ineffective and may not be legal.
Advice- continued zI would: yFeed NO moldy feeds to reproducing animals. yFeed a small test amount to growers but DO NOT encourage consumption. yIf no ill effect is observed in test, then dilute the suspect feed and incorporate small amount into normal diet.
WWW References to References zAustralian Mycotoxin Newsletter yhttp://www.aciar.gov.au/aciarptp/myconews.ht m zThird Joint FAO/WHO UNEP International Conference on Mycotoxins, Mar 1999 yhttp://www.fao.org/WAICENT/FAOINFO/ECONO MICS/ESN/mycoto/papers/