Molds/Mycotoxins in Drought Stressed Crops

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Molds/Mycotoxins in Drought Stressed Crops

• Lee Milligan, St. Croix County
• UW-Extension Agriculture Agent

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Potential Concerns for 2006

• Variability of ear maturity
• Variability of plant maturity
• Premature death of plants
• Extreme moisture variation in field
• Packing of silage in storage
• Poor fermentation
• Result
• Potential growth of molds, mycotoxins, yeast
• Poor bunk stability

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Common Mycotoxins

• Cool, wet weather
• Fusarium Toxins
• Deoxynivalenol (DON or Vomitoxin)
• Considered a marker
• T-2 toxin (T-2)
• Zearalenone (F-2)
• Fumonisin
• Hot, humid weather
• Aflatoxin

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Mold/Mycotoxin Concepts

• Critical factors for mold development.
• Temperatures above freezing
• Moisture above 20
• Oxygen
• Most molds do not produce mycotoxins.
• No relationship between mold spore count and
  mycotoxin development.
• Presence of mold does not indicate presence of
  mycotoxin.

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• Mycotoxins may be present with no visual
  indicator of mold.
• Freezing temperatures will not stop development
  of some mycotoxins.
• Drying/ensiling will not detoxify mycotoxins.
• No test will identify molds/mycotoxins as cause
  of herd health problem.
• Proper sampling for mold/mycotoxin tests
  critical.
• Over 400 identified mycotoxins.

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Effects of Molds/Mycotoxins

• Molds - Decrease digestability (5)
  - Decrease production (5-10)
• Mycotoxins Impact on milk production, weight
  gain greater than molds
• Mimic other herd health problems
• Depressed immune system
• Off-feed
• Diarrhea
• Hemorrhaging
• Abortions
• Reproduction issues
• D As, etc.

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When to Test for Molds/Mycotoxins

• All other possible causes of symptoms eliminated.
• Moldy feeds are fed.
• Significant changes in production/health occurred
  to large number of animals.

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Interpreting Mold Spore Counts

• Mold Spore Count per Gram
• Air-dried
• Under 500,000
• ½ to 1 million
• 1 to 2 million
• 2 to 3 million
• 3 to 5 million
• Over 5 million

• Feeding Cautions
• -
• Relatively low count
• Relatively safe
• Discount energy (x.95)
• Feed with caution
• Closely observe animals and performance
• Discount energy (x.95)
• Dilute with other feeds
• Discount energy (x .95)
• Observe Closely
• Discontinue feeding

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Types of Tests for Mycotoxins

• Quick Test (Qualitative)
• Immunoassays (Elisa tests)
• Thin Layer Chromatography (TLC)
• Use (Detect Specific Mycotoxin)
• Confirmatory Tests (Quantitative)
• High Pressure Liquid Chromatography(HPLC)
• Use Determine level of mycotoxins
• Detect several mycotoxins

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Adjust Energy Content of Moldy Feeds

• Test Wt.Lb/bu Non Moldy Moldy
• 54 1.000 0.950
• 50 0.987 0.937
• 45 0.971 0.921

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Managing Moldy/Mycotoxin Problems

• Ensure adequate levels of vitamins (A,E,B-1) and
  minerals (Se,Cu,Zn,Mn).
• Include aluminosilicate or bentonite in ration
• Dilution is the solution.
• Reduce intake of contaminated feeds.
• Eliminate highly contaminated feeds.
• Remove moldy layers of feed before feeding.

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• Harvest drought damaged forages at recommended
• Moisture (65-70)
• Theoretical Length of cut
• 3/4 inch with processor
• 3/8 inch without processor
• lt60 moisture
• 1/2 inch with processor
• 1/4 inch without processor

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• Pack silage well.
• Cover silage ASAP
• Consider use of innoculants/L.buchneri/ propionic
  acids on corn silage or high moisture corn
• Remove adequate amounts of forage daily
• Piles, bunkers 6 inches minimum
• Silos 2-4 inches

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Summary

• Potential exists for mold/mycotoxin problems
  exists in 2006.
• Most molds do not produce mycotoxins.
• Drying/ensiling does not detoxify mycotoxins.
• Diagnosing mold/mycotoxin problems requires
  review of total herd management.
• Sampling procedures critical to accurate analysis.