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Molds/Mycotoxins in Drought Stressed Crops

Molds/Mycotoxins in Drought Stressed Crops. Lee Milligan, St. Croix County UW-Extension Agriculture Agent. 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

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Molds/Mycotoxins in Drought Stressed Crops

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  1. Molds/Mycotoxins in Drought Stressed Crops • Lee Milligan, St. Croix County UW-Extension Agriculture Agent

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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 A’s, etc.

  7. 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.

  8. 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 Interpreting Mold Spore Counts

  9. 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

  10. Adjust Energy Content of Moldy Feeds Test Wt.Lb/buNon MoldyMoldy 54 1.000 0.950 50 0.987 0.937 45 0.971 0.921

  11. 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.

  12. Harvest drought damaged forages at recommended: • Moisture (65%-70%) • Theoretical Length of cut • 3/4 inch with processor • 3/8 inch without processor <60% moisture • 1/2 inch with processor • 1/4 inch without processor

  13. 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

  14. 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.

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