MYCOTOXINS - Animal Sciences
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Transcript MYCOTOXINS - Animal Sciences
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/