Spoiled Feeds, Molds, Mycotoxins and Animal Health

• Heating of feed and loss of energy and vitamins (A, D₃, E, K, thiamine)
• Reduced palatability due to dustiness
• Significant decreases in feed quality, often leading to thin cattle, weak calves, and abortions when rations aren’t properly supplemented
• Dusty mouldy feeds pose respiratory risks (e.g., Farmer’s Lung).

Spoilage (cm)	Spoilage (kg)	% of Bale Spoiled
5	72	11%
10	142	21%
15	207	31%
20	268	40%
25	324	48%

1. Mycotic infections – growth of molds in or on the animal
2. Mycotoxicosis – ingestion of toxins produced by molds
3. Allergic reactions – respiratory or systemic responses to inhaled spores

• Feed tests may detect mold but not mycotoxins
• Hundreds of mycotoxins exist; routine tests screen only a few
• Ruminant tolerance levels are poorly defined
• Not all mold growth results in toxin production

• Reduce kernel damage; harvest promptly.
• Dry grain quickly; store at <15% moisture.
• Use preservatives when appropriate.

• Mold can develop in the field or during storage, especially when feed moisture exceeds 15–16% and under warm temperatures.
• Moulds require air and carbohydrates to grow.
• Visible mold does not confirm mycotoxin presence.
• No definitive “safe” mold count exists, though counts above 1 million cfu/g are often considered high.

• Submit a representative sample of feed to a qualified laboratory for toxic mold analysis.
• Do not grind or roll grain samples prior to submission.
• Laboratory culturing requires 2–4 weeks to determine whether molds present have toxic potential.
• The presence of a toxic mold does not confirm mycotoxin production; consider additional testing for specific mycotoxins that may be produced.

• Many mold species produce multiple toxins, including some that cannot yet be detected through standard testing.
• Clinical signs depend on the specific mold and toxin involved.
• Cattle are generally more tolerant of mold toxins than swine or poultry, though young animals are more susceptible.

• Introduce moldy feeds gradually to avoid abrupt reductions in intake.
• Moldy hay is often unpalatable; many issues attributed to mold are actually the result of inadequate nutrition.
• Blend moldy feed with high‑quality ingredients. Feed value may decline by 10% or more when mold is present.

• Some molds, including Mucor and Aspergillus, are capable of causing mycotic abortions.
• Inhalation of high spore concentrations can lead to respiratory hypersensitivity, chronic lung disease, or death if exposure continues.
• Discontinue feeding moldy feed and seek professional support if health issues arise.

• Silage chopped at less than 50% moisture requires extra packing to eliminate air pockets.
• Removing oxygen is critical, particularly when plant sugars are low, cobs or grain are poorly developed, or mold is already present.
• Proper ensiling prevents further mold growth but does not reduce toxins already produced.

• Some producers apply anhydrous ammonia (approx. 2% of dry forage weight) to reduce oxygen and slow mold development.
• Effectiveness decreases when forage moisture falls below 30%.
• Ammonia increases crude protein, but does not increase energy.

• Use caution with silage that was improperly packed, too dry, overly mature, opened before 50 days, or shows aerobic spoilage.
• Maintain a proper silage face by removing 10–12 inches at each feeding, either daily or every second day.

• Caused by fungal infection of the placenta
• Abortion typically at 6–8 months
• Requires submission of fetus and entire placenta for diagnosis

• Caused by Listeria monocytogenes
• Linked to poorly fermented silage or areas of aerobic spoilage
• Causes abortion and/or encephalitis

• Associated with spoiled silage or grain
• Placental lesions resemble mycotic infections

• Fungal conversion of coumarol to dicoumarol leads to fatal bleeding disorders
• Causes abortions, weak calves, and hemorrhage

• Spoilage accelerates vitamin loss in stored forages
• Leads to abortions, weak or blind calves, and fertility issues

• Sporadic cases linked to moldy barley straw and suspected mycotoxin exposure

• Heavy spore inhalation may result in respiratory distress and subsequent abortion or even death if exposure to moldy feeds is continued.

• More severe in monogastrics; ruminants can detoxify some toxins.
• Symptoms: reduced gain, poor feed intake, infertility, abortions, lowered immunity.
• Zearalenone (Fusarium): major reproductive problems in pigs.

• Common Fusarium toxin; indicator of spoilage
• Ruminants show variable response but young and pregnant cattle are more vulnerable

• Causes infertility, prolapse, and feminization; more severe in pigs than cattle
• feminine characteristics in males, premature sexual development of young females, infertility in adults, abortion, stillbirth and the birth of deformed offspring.
• Cattle may have swollen vulvas and nipples while vaginal and rectal prolapse may occur.
• Also seen is a decrease in feed intake and perhaps feed refusal. The effect is most clearly seen in pigs.

• Fungus that infects the seed heads of rye, wheat, barley, oats and some grasses
• Causes gangrene, convulsions, abortions, and poor performance

• Caused by sporidesmin; grows on dead pasture litter
• results in liver damage and photosensitization

• Rare in Manitoba but highly toxic, grows on corn and cereal grains
• Cause abortions, deformed calves, poor immunity, and chronic performance losses

• Occasionally present in stored feeds; ruminants typically detoxify them unless young or high‑producing
• Can cause kidney and liver damage

• Mycotoxins are uncommon but possible in Manitoba.
• Many herd issues blamed on mycotoxins are more often due to:
• Poor-quality rations
• Vitamin deficiencies
• Infectious diseases
• Water issues

• Avoid for young, pregnant, or lactating animals.
• Introduce gradually and monitor a test group.
• Dilute mouldy feed with clean feed.
• Balance ration; supplement vitamin E.
• Test samples for mould identification.
• Feed moldy hay outside to reduce the effects of dust and spores

• A thorough herd history
• Proper feed testing for molds and mycotoxins
• Submission of affected tissues, especially placentas