Mycotoxins in Grain and Feed Industries

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I. Mycotoxin Development

Erin Bowers, Iowa State University, Agricultural Engineering

Charles Hurburgh, Iowa State University, Agricultural Engineering

Alison Robertson, Iowa State University, Plant Pathology

Learning Objectives

This learning module will focus on the development of fungi in the field and the production of mycotoxins under specific environmental conditions

Module Objectives• Understand the relationship of fungi and the environment

to mycotoxin production• Recognize harmful levels and effects of certain

mycotoxins on humans and animals

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Basics about Mycotoxins

• Chemical compounds produced by some fungi

• Contaminate grains, food, and feed worldwide

• Aflatoxins were the first mycotoxins discovered• Hundreds now known worldwide • 30 are significant health hazards

• 5 principle mycotoxins affect cereal grains (corn, wheat, rye, barley, oats)• aflatoxins, fumonisins, ochratoxin A,

deoxynivalenol (vomitoxin), and zearalenone

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Gibberella ear rot caused by Fusarium graminearum (Gibberella zeae )Source: Pioneer Hi-Bred, Intl

Fusarium head blighthttp://www.ars.usda.gov/Main/docs.htm?docid=9765

Fungal Disease Cycle

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Developing Fungus is Dependent on the Environmental Conditions During Pollination and Early Grain Development

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Mycotoxin(s) FungiFavorable Conditions

Primary Grains

AflatoxinsAspergillus flavus Aspergillus parasiticus

Hot and dry, drought

Corn, Durum (in EU)

Deoxynivalenol (Vomitoxin) Zearalenone

Fusarium graminearumFusarium culmorum

Cool, wet, humid at grain fill.

Corn, Wheat, Oats, Rye, Barley, Durum

FumonisinsFusarium verticillioidesFusarium proliferatum

Warm to hot, dry at and after flowering Corn

Ochratoxin APenicillium verrucosum Harvest conditions

determine Corn

Mycotoxins in Grain and Feed

• Significant food/feed safety hazard• Unavoidable contaminants

• Stable and persistent• Once present, they are hard to get out

• Remain intact after cooking, drying, freezing or storage conditions.

• Low levels (ppm or ppb) cause serious health problems for humans and animals

• There is usually no treatment for mycotoxin poisoning (mycotoxicosis)

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ppm: parts per millionppb: parts per billion

Economic Impact of Mycotoxins

• Worldwide, ~25% of crops are affected by mycotoxins• Annual economic burden of mycotoxins

to U.S. agricultural estimated at $1.4 billion• Product recalls (pet food is especially sensitive)

• 2005 dog food• 2008–2009 dog food• 2012 dog food and other feed

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Poisonous Ingredients in Food

Federal Food, Drug, and Cosmetic Act §402 [21 U.S.C. 342]

A food shall be deemed adulterated—(a)(1) If it bears or contains any poisonous of deleterious substance which may render it injurious to health; but in case the substance is not an added

substance such food shall not be considered adulterated under this clause if the quantity of such substance does not ordinarily

render it injurious to health.

Action Levels, Advisory Levels,and Guidance Levels

• Action Level: A level above which poisonous substances are believed to be harmful to humans or animals. FDA is prepared to intervene at these levels if necessary.

• Advisory Level: A level below which adverse health effects are not expected. FDA may intervene but often will not.

• Guidance Level: A level that prudent practice should not exceed; there is insufficient scientific data to establish an action or advisory level.

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Scientific strengthof evidence

Aspergillus Ear Rot-Aflatoxins

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Aspergillus ear rotSource: photo © Gary Munkvold

Aspergillus Ear Rot Disease Cycle and Symptoms

• Aspergillus flavus fungal spores survive between growing seasons in soil and crop residue

• Spores are carried by air movement and insects • Infects corn at pollination and during grain development

• Initial infection favored by heat and drought

• Late season and post-harvest growth (after grain maturity) and mycotoxin production favored by • Heat (80°F – 100°F)

• High humidity (≥ 85%)

• FDA has established action levels for aflatoxin.

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Action Level and Recommended Limits for Total Aflatoxins in Livestock Feed

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Class of Animals Feed Aflatoxin level

Finishing beef cattle Corn and peanut products 300 ppb

Beef cattle, swine or poultry Cottonseed meal 300 ppb

Finishing swine over 100 lb. Corn and peanut products 200 ppb

Breeding cattle and swine, mature poultry

Corn and peanut products 100 ppb

Immature animalsAnimal feeds and ingredients (excluding cottonseed meal)

20 ppb

Dairy animals, animals not listed elsewhere, or unknown

use (general market)Animal feeds and ingredients 20 ppb

Impact of Aflatoxins on Animals

• Aflatoxins are potent liver toxins and potent carcinogens• Negative effects seen in animals include:

• Dairy Cattle: Decreased breeding efficiency, lower birth weights, respiratory disorders, kidney damage

Toxin passes to milk

• Swine: Decreased growth rate, liver and kidney damage, system hemorrhages

• Poultry: Decreased egg production, embryo loss,decreased weight gain

• Horses: Lack of muscular control, lethargy, rapid weight loss

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Impact of Aflatoxins on the Grain Industry• Aflatoxin is a food/feed adulterant• Grain >20 ppb cannot be deliberately blended• FDA blending dispensations have been allowed in rare

instances when a large portion of the U.S. corn supply is affected• State by state basis• Resultant grain used only for specific livestock feed• >500 ppb aflatoxin grain has never been allowed to be blended

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Gibberella Ear Rot/Fusarium Head Blight-Deoxynivalenol

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Fusarium head blighthttp://www.ars.usda.gov/Main/docs.htm?docid=9765

Gibberella ear rotSource: Photo Courtesy of A. Robertson

Gibberella Ear Rot/Fusarium Head Blight Disease Cycle and Symptoms

• Overwinters on crop residue • Predominantly occur in the northern Corn Belt• Optimal conditions for colonization are

• Cool with high humidity • Frequent precipitation during early grain fill

• Typically infects through the silk (corn) or head (wheat) two to six days after emergence

• Fungal infection preceeds mycotoxin production• Deoxynivalenol (also known as DON or vomitoxin) • Zearalenone

• FDA has established advisory levels for deoxynivalenol

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Advisory Levels for Deoxynivalenol in Livestock Feed

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Class of AnimalsFeed Ingredients & portion of the

diet

DON level in ingredients and (finished feed)

Ruminating beef and feedlot cattle older than 4 months

10 ppm (10 ppm)

Ruminating dairy cattle older than 4 months

Grain and grain by-products not to exceed 50% of the diet

10 ppm (5 ppm)

ChickensGrain and grain by-products not to

exceed 50% of the diet10 ppm (5 ppm)

SwineGrain and grain by-products not to

exceed 20% of the diet5 ppm (1 ppm)

All other animalsGrain and grain by-products not to

exceed 40% of the diet5 ppm (2 ppm)

Deoxynivalenol (DON, Vomitoxin)

• Most commonly encountered mycotoxin in food and feed.

• Swine are particularly sensitive, compared to other livestock.

• Negative effects on swine and young animals:• Feed suppression• Feed refusal• Reduced weight gain• Impaired organ function

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Mycotoxin deoxynivalenol may induce vomiting in swine.

Zearalenone is often found in association with Deoxynivalenol

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Zearalenone

• Estrogenic activity in swine and dairy that manifests as reproductive effects

• Negative effects on cattle:• Infertility• Reduced milk production• Hyper-estrogenism

• Negative effects on swine:• Enlarge mammae• Swelling of uterus and vulva• Atrophy of the ovaries• Withered testes

• There are no FDA action, advisory, or guidance levels

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Fusarium Ear Rot-Fumonisins

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Scattered or groups of infected kernels are typical of Fusarium ear rotSource: Pioneer Hi-Bred Intl, Inc.

Fusarium ear rot Source: ©Gary Munkvold

Fusarium Ear Rot Disease Cycle and Symptoms

• Most common corn ear disease in the Midwest • Fusarium verticillioides usually overwinters in crop residue• Favored by warm-hot, dry weather during grain fill• Also favoring infection are:

• Optimum growth temperature ~86°F • Drought stress before and after silking • Damage to kernels by insects, birds, hail

*Prevention of insect feeding results in lower

levels of fumonisins (e.g. Bt corn)

• The FDA has provided guidance levels

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Fusarium ear rot Source: Gary Munkvold

Guidance Levels for Total Fumonisins in Livestock Feed

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Class of Animal Feed Ingredients & portion of the diet

Fumonisin level in ingredients and (finished feed)

Equids and rabbits Corn and corn by-products not to exceed 20% of the diet 5 ppm (1 ppm)

Swine and catfish Corn and corn by-products not to exceed 50% of the diet 20 ppm (10 ppm)

Ruminants, Poultry, and mink (all breeding)

Corn and corn by-products not to exceed 50% of the diet 30 ppm (15 ppm)

Ruminants ≥3 months old being raised for slaughter and

mink for pelt production

Corn and corn by-products not to exceed 50% of the diet 60 ppm (30 ppm)

Poultry being raised for slaughter

Corn and corn by-products not to exceed 50% of the diet 100 ppm (50 ppm)

All other species or classes of livestock and pet animals

Corn and corn by-products not to exceed 50% of the diet 10 ppm (5 ppm)

Fumonisin Symptoms of Exposure

• Adverse effects in animals• Horses: Leukoencephalomalacia• Swine: Liver damage, pulmonary

edema • Cattle and Sheep: Mild liver damage,

moderate feed refusal

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Infected kernels scattered or clustered are typical of Fusarium ear rotSource: Photo Courtesy of Pioneer HiBred Intl, Inc.

Penicillium Ear Rot-Ochratoxin A

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Penicillium ear rot and affected kernelsSource: Photo Courtesy of Don White, University of Illinois

Penicillium species produce ochratoxin ASource: Photo Courtesy of Don White, University of Illinois

Penicillium Ear Rot Disease Cycle and Symptoms• Primarily caused by Penicillium verrucosum • Fungus invades at maturity, not during grain

development• Optimal growth conditions for fungus:

• Temperatures between 68-77°F • Grain moisture content ≥ 16%

Harvested corn stored at moisture levels >18% can increase disease severity

• Humidity > 80% during and after maturity

• Most commonly found in fields infested with stalk boring insects

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Ochratoxin A Symptoms of Exposure

• Ochratoxin A is primarily a kidney toxin

• Swine and poultry are the primary livestock affected

• Adverse effects in swine and poultry• Reduced feed intake, dehydration• Growth retardation• Kidney dysfunction• Diarrhea and excessive urine production• Reduced egg production (poults)• Vomiting (swine)

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Cladosporium

Many fungi in one place!

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FusariumGibberella

Penicillium Trichoderma

Sac County, Iowa August 9, 2009

Fusarium

Summary

• Mycotoxins are:• Chemical compounds• Produced by specific fungi• Contaminants of crops and other commodities worldwide

• 5 mycotoxins monitored under FDA surveillance programs• Aflatoxins• Deoxynivalenol (Vomitoxin)• Zearalenone• Fumonisins• Ochratoxin A

• Toxic to humans and animals at very low levels• Mycotoxin-producing fungi survive in soil/on crop residue

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Summary

• The FDA has established • Action levels for aflatoxin• Advisory levels for deoxynivalenol• Guidance levels for fumonisins

• Growing-region climate and weather determine type and severity of mycotoxin risk• Especially conditions during pollination, grain fill, anthesis (flowering)

• Climate and weather monitoring can be used as tools to

1) predict mycotoxin risk

2) direct testing efforts appropriately

3) protect the industry from large-scale contamination

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This training was a joint effort of

*Funding for this Grain and Feed Mill Operations course was made possible, in part, by the Food and Drug Administration through grant (1U54FD004333-01), views expressed in written materials or publications and by speakers and moderators do not necessarily reflect the official policies of the Department of Health and Human Services; nor does any mention of trade names, commercial practices, or organization imply endorsement by the United States Government.*