findings on mycotoxin contamination in silages and key … · 2017. 10. 16. · mycotoxins...

International Dairy Topics — Volume 14 Number 4 21

by Karin Nährer, MycotoxinProduct Manager andAnnamaria Boczonadi, TechnicalProduct Manager, Biomin.

Amajor component of rumi-nant feed rations are silages.Mycotoxins – fungal metabo-

lites toxic to animals and humansproduced by common moulds foundin almost all types of grains – canand often do contaminate silages,impairing animal performance andproductivity.

Furthermore, some mycotoxinscan be carried over from ingestedfeed into animals’ milk, such as thecase with aflatoxin. More than 90%of mycotoxins found in feed arealready produced in the field, so thefirst step to avoid mycotoxin conta-mination in silages should be to min-imise the risk at the site of cropproduction. In part because mycotoxins aredifficult to destroy and despite theuse of preventative methods in thefield during harvest and storage,

mycotoxin contaminations still posea challenge to dairy cows. Anoverview on the most importantfungal species focusing on the genusFusarium, Aspergillus and Penicilliumfound in silages is shown in Table 1.Mycotoxin contamination is notaccurately detected by sight. Theabsence of visible mould in silagedoes not necessarily mean that it isfree of mycotoxins. The conversealso holds true: heavily infested, visi-bly mouldy silage does not necessar-ily contain severe levels of

mycotoxins. Therefore, monitoringfor mycotoxins regularly and apply-ing a mycotoxin risk managementsolution is extremely important.

Proper testing methods

Mycotoxin tests should be con-ducted on the feedstuffs and feedprior to feeding. An essential step indetermining the mycotoxin contami-nation level in silages and the foun-dation for a high quality mycotoxintesting is proper sampling. Mycotoxin levels within the silovary considerably due to the inhomogeneous distribution of thesetoxins, so a suitable sampling proce-dure should be followed. It is rec-ommended to use the guidelinesaccording to European CommissionRegulation (EC) No 401/2006 in‘laying down the methods of sam-pling and analysis for the official con-trol of the levels of mycotoxins infoodstuffs’. In general, the numberof incremental samples depends onthe lot type (solid feed orroughages) and on the lot size.

Contamination in numbers

The latest Biomin Mycotoxin Surveycovers 6,844 agricultural commoditysamples from 64 countries to iden-tify the presence and potential riskposed to livestock animal produc-tion by mycotoxins worldwide. About 300 corn silage sampleswere investigated to get an insight

Table 1. Classification of mycotoxin-producing fungi in silages.

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Findings on mycotoxincontamination in silagesand key prevention tips

Fungi Mycotoxin Possible effects Colour

Aspergillusfumigatus

Gliotoxin,Tryptoquivaline,Trypacidin

Liver and kidney damage, immune suppression,incidental abortion

Creamy yellow-(dark) green

Aspergillusflavus

Aflatoxins

Liver diseases; carcinogenic effects; haemorrhages(intestinal tract, kidneys); reduced growth rate;diminution of performance; immune suppression,transferred into the milk

Dull yellow,brownishdark green

Cyclopiazonic acidNecrotic effects (liver, gastrointestinal tissue, kidneys,skeletal muscles); carcinogenic; neurotoxic

Aspergillusochraceus

OchratoxinsNephrotoxic; carcinogenic; mild liver damage; enteritis;teratogenic effects; poor feed conversion; reducedgrowth rate; immune suppression

Yellow-pink

Fusariumspp

Trichothecenes(e.g. deoxynivalenoland T-2 toxin)

Digestive disorders (vomiting, diarrhoea, feed refusal);reduced weight gain; haemorrhages (stomach, heart,intestine, lung, bladder, kidney); oedema; oral lesions;dermatitis; blood disorders; infertility; degeneration ofbone marrow; slow growth; immune suppression Yellowish, red,

brownish-red topink or colourless

ZearalenoneOestrogenic effects; oedema of vulva; enlargement ofuterus; atrophy of testicles; atrophy of ovaries;enlargement of mammary glands; infertility; abortion

FumonisinsPulmonary oedema; nephro- and hepatotoxic; immunesuppression

Penicilliumspp

OchratoxinsNephrotoxic; carcinogenic; mild liver damage; enteritis;teratogenic effects; poor feed conversion; reducedgrowth rate; immune suppression (Dark) green-

blue to greyPatulin Mutagenic; genotoxic; neurotoxic; immune suppression

Citrinin Nephrotoxic; teratogenic; hepatotoxic

Penicilliumroqueforti

PR toxin Intestinal irritation, abortion, reduced fertilityGreen – blue green

Fusarium culmorum.

22 International Dairy Topics — Volume 14 Number 4

into the occurrence of aflatoxins(Afla), zearalenone (ZEN), deoxyni-valenol (DON), T-2 toxin (T-2),fumonisins (FUM) and ochratoxin A(OTA).The results of this study (Table 2)show that mycotoxins constitute awidespread challenge that occurunder different environmental condi-tions across the globe. Silages areafflicted by a wide variety of myco-toxin types, and in over half of allsamples, two or more mycotoxinswere identified. This multiple mycotoxin presencecan be dangerous because somemycotoxins are known to have addi-tive or synergistic negative effects onanimal health.

A three-pronged solution

Because groups of mycotoxins differstructurally from one another, sev-eral strategies are needed tocounter the wide range of mycotox-ins found in the field.The three strategies to counteractdifferent mycotoxins are biotrans-formation, adsorption and biopro-tection.Biotransformation is the most sci-entifically advanced and effectivemethod available to counteractmycotoxins. It works by transform-ing their chemical structure, trans-

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forming them into non-toxic andenvironmentally-safe substances thatpass through the animal withoutcausing harm. The key advantages ofbiotransformation is that it is specific

(targeting mycotoxins) and irre-versible (cannot be undone). Thismode of action targets fumonisins,trichothecenes, zearalenone andochratoxin A.

Adsorption, or binding, is the mostwidespread and longstandingmethod to counteract certainadsorbable mycotoxins such as afla-toxins and ergot alkaloids. Bioprotection relies on an innova-tive mix of natural ingredients toprovide immune support andcounter the toxic side effects causedby mycotoxins.

Conclusion

A number of common moulds foundin the field produce harmful myco-toxins that impair dairy cow healthand performance. The latest surveydata shows that mycotoxins arequite common. Good silage management is essen-tial to avoid further growth ofmoulds and thereby prevent furthermycotoxin production. Robust mycotoxin risk manage-ment includes regular testing of feedand feedstuffs along with a multi-pronged approach to combatingmycotoxins and their negativeeffects.A well designed mycotoxin riskmanagement solution program iscrucial to avoid economic losses dueto mycotoxins in dairy cows. n

References are available from the author on request

Penicillium carneum.Aspergillus sp.

Table 2. Biomin Mycotoxin Survey results for silage samples sourcedworldwide in 2014. Fusarium toxins, such as ZEN, DON and FUMwere found to be the most prevalent ones.

Afla ZEN DON T-2 FUM OTA

Number samples tested 137 223 275 110 143 127

% of contamination 4% 68% 71% 4% 45% 6%

Average of positive (ppb) 6 290 2543 16 319 2

Maximum value found (ppb) 15 3055 13920 47.78 3939 5