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/