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Fungi and molds that grow in grains or forage can produce poisonous compounds (or toxins). These compounds are collectively called “mycotoxins” and may affect the health of both humans and livestock. More than four hundred mycotoxins have been identified, but only a small number are of concern to livestock.
¶ A. What are “T‐2”, “HT‐2”, and “DAS”?
Mycotoxins produced by metabolism of Fusarium molds
Class of compounds called “Type‐A trichothecenes”
DAS = “diacetoxyscipernol”
T‐2 toxin produced by Fusarium sporotrichioides
Also produces HT‐2 and DAS toxins
DAS is least common
Are potential problem in cereal crop grains
Mainly found in unharvested grains
Corn, wheat, rice, barley, oats, rye, etc.
May also be found in finished feeds
U.S. Food and Drug Administration (FDA) has not set action, advisory, or guidance levels Concern level
Level indicating possible favorable conditions for mycotoxin development
Additional testing of feed ingredients or rations may be prudent
Limit amounts fed to livestock if moderate performance effects are observed
Discontinue use (at least temporarily) if pronounced chronic symptoms or acute clinical symptoms are observed
Potentially harmful level
Indicates probable involvement of zearalenone in reduced performance, chronic symptoms, or acute clinical symptoms
Discontinue feeding ‐ at least temporarily ‐ if either chronic or acute symptoms are noted
Observe animals closely if symptoms are absent
Continue testing feedstuffs or rations
Toxin production greatest with conditions that promote mold growth
High humidity and temperatures from 40° to 75°F (6° to 24°C)
Cold, wet weather during flowering
Maximum T‐2/HT‐2 toxin production at temperatures below 60°F
Drying grain quickly before storage is strategy to minimize fungal growth and mycotoxin production
Safe moisture thresholds:
Wheat, barley, oats: 14% to 15%
Corn: 14%
Rice: 13% to 14%
Minimize insect damage
Mycotoxin Name Concern Level Potentially Harmful
Cattle Swine Poultry
----- mg/kg or ppm* -----
T-2 0.25 0.7 to 1.5 0.7 to 1.5 1.0 to 3.5
HT-2 0.25 1.5 to 3.0 1.5 to 3.0 0.7
DAS 0.25 0.7 to 1.5 0.4 to 1.0 ----
*multiply mg/kg or ppm by 1000 to determine μg/kg or ppb
1. Trichothecenes inhibit protein synthesis; disrupt DNA/RNA synthesis
Target cells with rapid division
Gastrointestinal tract linings
Precursor cells forming red and white blood cells
Decreases antibody levels
Sperm precursor cells
Swine are more susceptible than other animals
May be synergy between T‐2 toxin and aflatoxin Swine
Skin lesions
Digestive tract inflammation, hemorrhage
Vomiting, feed refusal
Possible infertility
Reduced milk at 1.0 to 2.0 mg/kg (1000 to 2000 µg/kg)
Cattle
Feed refusal, reduced consumption
Pronounced milk reduction
Ketosis
Sometimes diarrhea
Hemorrhage at 1.0 to 2.0 mg/kg (1000 to 2000 µg/kg)
Swine
Weight loss
Hemorrhage
Diarrhea
Possible infertility at 2.0 to 4.0 mg/kg (2000 to 4000 µg/kg) or lower
Cattle
Feed refusal, reduced consumption
Pronounced milk reduction
Ketosis
Sometimes diarrhea
Hemorrhage at 2.0 to 4.0 mg/kg (2000 to 4000 µg/kg)
Swine
Estrogenic effects, infertility
Poor gains
Oral and gastroenteric necrosis and hemorrhage at 0.5 to 1.0 mg/kg (500 to 1000 µg/kg)
Cattle
Feed refusal, reduced consumption
Pronounced milk reduction
Ketosis
Sometimes diarrhea
Hemorrhage at 1.0 to 2.0 mg/kg (1000 to 2000 µg/kg)
Adams, R.S. et.al. Mold and mycotoxin problems in livestock feeding. DAS 93‐21. Pennsylvania State Univ. Coop. Ext. Svc. 17 pg. http://www.das.psu.edu/research‐extension/dairy/nutrition/pdf/mold.pdf/view?searchterm=mycotoxin
Jacobsen, et.al. 2007. Stored Grain: Trichothecene Mycotoxins, T‐2, HT‐2, Diacetoxyscirpenol (DAS). Bugwood wiki, Center for Invasive Species and Ecosystem Health at the University of Georgia. https://wiki.bugwood.org/uploads/TrichotheceneMycotoxinsDiacetoxyscir penol‐StoredGrain.pdf accessed 18Sep2017
Romer Labs. 2004. Knowledge Library, “What is T‐2/HT‐2?” https://www.romerlabs.com/en/knowledge‐center/knowledgelibrary/articles/news/what‐is‐t‐2ht‐2/ accessed 18Sep2017
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