Feeding Fusarium Contaminated Grain to Livestock

Overview

Fusarium Head Blight (FHB) affects wheat, barley, oats, rye, and some forage grasses. Under specific environmental conditions, the fungus can produce the mycotoxin deoxynivalenol (DON). DON is considered a mild toxin, but it may still reduce feed intake, performance, and immune function.

Different livestock species metabolize DON differently, resulting in varying tolerance levels.

Species Tolerance and Guidelines (Complete Ration, DM Basis)

Based on Agriculture & Agri-Food Canada (AAFC) guidelines

Dairy Cattle — 1 ppm

Research shows dairy cattle may tolerate higher DON levels than originally thought.
Trials indicate 6–8 ppm DON resulted in no reduction in milk yield or intake.

Growing Beef Cattle & Sheep — 5 ppm

Growing/finishing animals tolerate higher levels.
Studies show cattle and lambs fed 9–18 ppm DON showed no performance issues.

Pregnant Cows & Ewes

Research indicates no negative effects on reproduction at tested DON levels.
Trials feeding 7–12 ppm DON during gestation showed normal birth weights and survival.

Horses — 1 ppm

Limited data.
A study feeding ~6 ppm DON for 40 days showed no health or performance effects.

Swine — 1 ppm

Most sensitive species.
Expected effects:

1–2 ppm: ~5% feed refusal
4 ppm: ~25% refusal
10–20 ppm: complete refusal possible

Vomiting is rare but reported at high levels.
Avoid DON‑contaminated grain for weanlings and breeding stock.

Poultry — 5 ppm

Most tolerant species.
Some studies show 20–50 ppm DON without production losses.

Interpreting DON Risk

Animal response can be influenced by:

Stress (production, health, nutrition, overcrowding)
Presence of other mycotoxins (synergistic effects)
Variability of DON distribution within fields and grain lots

Stressed animals may show toxicity symptoms at lower DON levels.

DON in Straw

DON resides almost entirely in fusarium‑damaged kernels, not stems.
Straw is typically low risk unless grain or chaff is present.
Avoid feeding contaminated straw to horses or using it as hog bedding.
The quick test - ELISA tests for straw are unreliable; Gas Chromatography – Mass Spectrophotometer - GC‑MS testing is recommended.

DON in Greenfeed & Silage

DON peaks 2–3 weeks before grain maturity.
Greenfeed/silage can have higher DON in seed heads, but stem and leaf tissues dilute levels.
Proper ensiling prevents further mold growth but does not destroy DON already present.
Silos must remain airtight.

DON in High‑Moisture Grain

Harvested before maturity, so DON levels may be elevated.
Unlike silage, there is no dilution effect from stems/leaves.

Sampling & Testing Procedures

To obtain representative samples:

Unharvested crop: combine a typical swath.
Harvested grain: collect 15–20 sub‑samples from various bin locations or during loading/unloading.
Mix thoroughly, then submit a composite sample.

Keep in mind:

DON distribution is highly variable, leading to fluctuating test results.

Practical Feeding Considerations

Test suspect grain before feeding.
Monitor livestock for:

Feed refusal
Decline in intake
Performance issues

Adjust rations immediately if symptoms appear.

Feed and mycotoxin results are guidelines, not guarantees—animal observation remains essential.