MYCOTOXINS
Dale M. Forsyth
Dept of Animal Sciences
Purdue University
MYCOTOXINS
Toxins produced by fungi
Metabolic 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 edible
Mushrooms are fungi
Moldy 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
Rat
Autoclaved
Diplodia
Autoclaved
Diplodia
Autoclaved
Diplodia
31.8
30.3
2.27a
1.87b
7.19a
4.43b
12.0a
11.0b
28.2a
25.7b
12.0
11.6
3.70
4.88
26.3
27.3
Autoclaved
Diplodia
203.4b
286.5a
5.16
4.76
6.82b
4.60a
Mouse
Hamster
Guinea
pig
Wkly
gain, g
Feed, % F/G
of BW
Effect of fungus Damage on
Digestibility of Corn by Rats
Item
Sound Diplodia Sound Fusarium
zeae
Moniliforme
Energy studies
Dig. Energy,%
90.7
89.4
91.0
89.5
Body Wt gain
100
95
100
81
83.6
81.2
81.9
75.0
Protein studies
Dig. Nitrogen,%
(Corn essentially 100% Fungus damaged)
Mitchel & Beadles, 1940
Feeds Most Susceptible to
Fungi-producing Mycotoxins
Corn
Wheat
Oats
Barley
Recently
Sorghum
Cottonseed
Peanut 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
Decrease
Decrease
Decrease
milling quality
seed germination
dry matter
feeding value (sometimes)
Mycotoxins can cause:
Death
Poor performance from low FI, ADG
Respiratory problems
Reproductive problems
Liver, kidney or other organ damage
Cancer
Mycotoxins
Factors causing variation in effects
Species, breed
Age
Sex
Nutritional status
Other diseases
Other mycotoxins
Extent 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) Fusarium
ZEARALENONE
(Gibberella)
AFLATOXIN - Aspergillus flavus
FUMONISON - Fusarium moniliforme
ERGOT (ergotamine, dihydroergosine)
Claviceps
Trichothecene Mycotoxins
Nivalenol
Deoxynivalenol
T-2 toxin
HT-2 toxin
Diacetoxyscirpenol
Triacetoxyscirpendiol
Fusarenone X
Verrucarin A, B, J
Roridin A, D, E, H
Many 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 time
Slow drying weather at harvest
Varieties 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 animals
Canada: 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 possible
Lengthened or absent estrous cycle
Little or no effect on growth
Little effect of Z on growth
ZEN
GAIN
FEED
INTAKE
F/G
0
10
20
40
10.3
10.7
11.0
12.2
.75
.75
.81
.82
.49
.51
.49
.53
Initial wt 10 kg, fed 4 wk. James & Smith (1982)
Organisims - 2
Aspergillus spp. - Especially A. flavus
Also A. parasiticus and Penicillium
puberulum.
Soil organism (A. flavus), so quite
common, especially in peanuts.
CAN produce AFLATOXIN
AFLATOXIN 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 synthesis
Poor gain
Liver damage
Susceptibility to Infection
Residues / carcinogenicity
Reproduction in swine not primarily
affected
Aflatoxin on Performance
Growing Swine (53 Kg initial)
PPB Final Wt,
Kg
20
104
385
97
750
91
1480
80
ADG
(Kg)
.77a
.67b
.57b
.41c
F/G
3.74a
3.78a
3.71a
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 seeds
Chromatography
Including rapid minicolumn in-field tests
Dealing with AFLATOXIN
FDA ACTION level is 20 ppb
Small amount may contaminate huge
quantities
Strategies to decontaminate must have
FDA approval in USA.
Some methods, however, can lower
aflatoxin levels.
DECONTAMINATION
Cleaning, separation, sorting
AMMONIATION
Binding Agents
Sodium aluminosilicate and hydrated sodium
calcium aluminosislicate
NOT GRAS for binding mycotoxins.
MUCH BETTER TO PREVENT FORMATION
Preventing Mycotoxins
Use “clean” procedures.
Prevent contamination
Inhibit mold growth
Drying
Refrigeration
Mold inhibitors
Additional Mycotoxins
FUMONISON
Deadly to horses
equine leukoencephalomalacia
Swine - pulmonary oedema
Renal 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 Horses
10 ppm for swine
50 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/ECONO
MICS/ESN/mycoto/papers/