Mycotoxins
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Transcript of Mycotoxins
MYCOTOXINS
Dale M. Forsyth
Dept of Animal SciencesPurdue University
MYCOTOXINS
Toxins produced by fungiMetabolic products or by-products of
fungi (molds)
Why Great Concern?
Some mycotoxins are DEADLY at very small dosages.
Some mycotoxins are carcinogenic.Some mycotoxins cause huge losses
in productivity in animals.
Most fungi do not produce Mycotoxins
Many fungi are edibleMushrooms are fungiMoldy feeds may be
degraded without presence of mycotoxin, or may be unaffected in value.
some material courtesy of Mark
Diekman
DIPLODIA Infested Corn
Specie Diet Wklygain, g
Feed, %of BW
F/G
Rat AutoclavedDiplodia
31.830.3
12.0a
11.0b3.704.88
Mouse AutoclavedDiplodia
2.27a
1.87b28.2a
25.7b26.327.3
Hamster AutoclavedDiplodia
7.19a
4.43b12.011.6
Guineapig
AutoclavedDiplodia
203.4b
286.5a5.164.76
6.82b
4.60a
Effect of fungus Damage on Digestibility of Corn by Rats
Item Sound Diplodiazeae
Sound FusariumMoniliforme
Energy studies Dig. Energy,% 90.7 89.4 91.0 89.5
Body Wt gain 100 95 100 81
Protein studies
Dig. Nitrogen,% 83.6 81.2 81.9 75.0
(Corn essentially 100% Fungus damaged)
Mitchel & Beadles, 1940
Feeds Most Susceptible to Fungi-producing Mycotoxins
CornWheatOatsBarleyRecently
Sorghum
CottonseedPeanut meal
Rye
Moldy grain is usually nontoxic
Competition between toxic and nontoxic molds.
Entire mold population is not producing mycotoxin
Conditions for growth are different for mold growth vs mycotoxin production
Molds that attack grain can:
Decrease grade Kernel damage odor
Decrease milling qualityDecrease seed germinationDecrease dry matterDecrease feeding value (sometimes)
Mycotoxins can cause:
DeathPoor performance from low FI, ADGRespiratory problemsReproductive problemsLiver, kidney or other organ damageCancer
MycotoxinsFactors causing variation in effects
Species, breedAgeSexNutritional statusOther diseasesOther mycotoxinsExtent of exposure
Some mycotoxins are formed in the field, some in storage
Storage conditions that favor production of mycotoxins: Temperature (40 - 90o F ; 4 - 32o C) Relative Humidity (> 70%) Moisture (22-23% in grain) Oxygen (1-2%)
MOST COMMON MYCOTOXINS in the USA
DEOXYNIVALENOL (vomitoxin) FusariumZEARALENONE (Gibberella)AFLATOXIN - Aspergillus flavus FUMONISON - Fusarium moniliformeERGOT (ergotamine, dihydroergosine) Claviceps
Trichothecene Mycotoxins
NivalenolDeoxynivalenolT-2 toxinHT-2 toxinDiacetoxyscirpenolTriacetoxyscirpendi
olFusarenone X
Verrucarin A, B, JRoridin A, D, E, HMany Others (29+)
These are “field” toxins, not “storage” toxins
Other Mycotoxins of Growing Interest
Ochratoxins Produced by Penicillium verrucosum
and several spp. Of Asperfillus. Potently nephrotoxic and carcinogenic,
teratogenic and immunotoxic. Public health problem, but little
evidence of problematic instances in swine.
Other Common Molds
Penicillium Common blue mold Capable of producing mycotoxin,
usually does not.Diplodia
Affected cattle and sheep in Africa
Organisms - 1
Fusarium Taxonomy is quite confusing Has had classification changed various
times Fusarium roseum, Fusarium graminearum
and Gibberella zeae are all terms applied to the same thing.
Gibberella zeae is the “perfect” (reproductive) stage
Nickname “GIB” corn.
Fusarium toxins
Deoxynivalenol Feed refusal Emesis (so nicknamed “vomitoxin”)
Zearalenone Estrogenic effects
Deoxynivalenol
Feed refusal factor for pigs.
Emetic (vomiting) but seldom see pigs
vomiting, refuse feed
Deoxynivalenol - Feed Refusal
Nearly complete refusal at low dosages (~5 ppm) by swine.
Reduced intake and poor performance at very low dosages (~1 ppm or less)
Other animals much much less affected!
DON doesn’t account for all the refusal, other metabolites are involved (though seldom tested for).
DON Does Not affect Reproduction
Purified Deoxynivalenol
DON, ppm CL's Fetuses
0 13.2 10.0
2 14.2 11.7
4 13.0 9.2
8 13.7 11.0
Field conditions that favor Gib fungus
Cool, wet weather at silking timeSlow drying weather at harvestVarieties with tight husks
Recovery of DON-infected CORN
DON is very stable! Heat, chemicals, etc.
have no effect.
DON is water soluble! So, can be leached out
and washed away. Not too practical, so
Advice: feed to other animals instead.
Guidelines on Levels
FDA guidelines on DON in feeds 10 ppm in grains, by-products for
chickens & cattle (5 ppm total ration) 5 ppm in ingredients for swine max
inclusion rate 20% (1 ppm total ration) 5 ppm ingredients max inclusion 40% (2
ppm) all other animalsCanada: 1 ppm pigs, calves, lambs,
lactation. 5 ppm adult cattle, sheep, poultry
Zearalenone
Prepuberal gilts show enlarged, swollen vulva as if in estrus
Interrupted reproductive cycles in female swine
Prolapse of the vulva possibleLengthened or absent estrous cycleLittle or no effect on growth
Little effect of Z on growth
ZEN GAIN FEEDINTAKE
F/G
0 10.3 .75 .4910 10.7 .75 .5120 11.0 .81 .4940 12.2 .82 .53
Initial wt 10 kg, fed 4 wk. James & Smith (1982)
Organisims - 2
Aspergillus spp. - Especially A. flavusAlso A. parasiticus and Penicillium
puberulum.Soil organism (A. flavus), so quite
common, especially in peanuts.CAN produce AFLATOXINAFLATOXIN is probably the worst
common mycotoxin we deal with.
AFLATOXIN
Most references to “mycotoxin”, unspecified, refer to Aflatoxin. There is NO reason to assume similarities
with other mycotoxins, in any regard.Can be deadly at low dosages
In 1st outbreaks (~1960) 100,000 turkeys died + many ducks.
Associated with “groundnut” (peanut) meal
Aflatoxin (cont)
Occurs in corn and other grains also.Temperature > 12 C (54 F) and high
humidity (83% at 30 C). Therefore usually a bigger problem in
USA in South and Southeast.Hepatic toxin - zonation, biliary
proliferation, degeneration.Carcinogenic in chronic situations.
AFLATOXIN EFFECTS
Inhibits protein synthesisPoor gainLiver damageSusceptibility to InfectionResidues / carcinogenicityReproduction in swine not primarily
affected
Aflatoxin on Performance
Growing Swine (53 Kg initial)
PPB Final Wt,Kg
ADG(Kg)
F/G
20 104 .77a 3.74a385 97 .67b 3.78a750 91 .57b 3.71a1480 80 .41c 3.97
Aflatoxin (cont)
A few of many Aflatoxins
Aflatoxin Detection
Black Light test - BYG fluorescence Abused. Use very carefully by trained
people Presumptive test for organism, not
aflatoxin Many other things fluoresce, including
broken soybean seedsChromatography
Including rapid minicolumn in-field tests
Dealing with AFLATOXIN
FDA ACTION level is 20 ppbSmall amount may contaminate
huge quantitiesStrategies to decontaminate must
have FDA approval in USA.Some methods, however, can lower
aflatoxin levels.
DECONTAMINATION
Cleaning, separation, sortingAMMONIATIONBinding Agents
Sodium aluminosilicate and hydrated sodium calcium aluminosislicate
NOT GRAS for binding mycotoxins.
MUCH BETTER TO PREVENT FORMATION
Preventing Mycotoxins
Use “clean” procedures.Prevent contaminationInhibit mold growth
Drying Refrigeration Mold inhibitors
Additional Mycotoxins
FUMONISON
Deadly to horses equine leukoencephalomalacia
Swine - pulmonary oedemaRenal toxicity and hepatotoxic
FUMONISON
Actually 8 analogs known, only B1, B2 & B3 often found.
ORGANISM is Fusarium moniliforme [=F. verticillioides (Sacc.) Nirenberg] or F. proliferatum
Fusarium moniliforme is VERY COMMON but seldom produces mycotoxin.
Fumonison - Levels
< 5 ppm for Horses10 ppm for swine50 ppm for cattle
ERGOT
Traditionally, this is a disease of RYE and other small grains.
New threat in Grain Sorghum (milo) to Western Hemisphere. Has been prevalent in Africa for decades
(claviceps africana) Has very rapidly spread in last 2 years,
now in USA.
Sorghum Ergot
Pathogen causes ovary to exude a sticky liquid.
Dihydroergosine at .6 ppm decreases FI & ADG.
Effect appears to be from poor feed intake Dean et al, 1999
Traditional Ergot
Claviceps purpurea produces ergotamine and other alkaloids. Psychoactive - convulsions,
hallucinations, abortions Paralysis, GI disturbance, gangrene of
extremities, death.
ADVICE
Avoidance of Mycotoxin formation is best in every case
Some procedures for decontamination exist (ammonia, HSCAS), but are different for different mycotoxins, may be ineffective and may not be legal.
Advice- continued
I would: Feed NO moldy feeds to reproducing
animals. Feed a small test amount to growers but
DO NOT encourage consumption. If no ill effect is observed in test, then
dilute the suspect feed and incorporate small amount into normal diet.
WWW References to References
Australian Mycotoxin Newsletter http://www.aciar.gov.au/aciarptp/
myconews.htm
Third Joint FAO/WHO UNEP International Conference on Mycotoxins, Mar 1999 http://www.fao.org/WAICENT/FAOINFO/
ECONOMICS/ESN/mycoto/papers/