Interpretation
Livestock responses to mycotoxin exposure vary depending on:
-
-
-
Species
-
Physiological status (pregnant, lactating, etc.)
-
The combination of mycotoxins present
-
Exposure to other stressors
The table below summarizes concern and potentially harmful thresholds in total ration dry matter from various sources.
-
-
Safe thresholds for individual feeds depend on the proportion of the diet a feed represents and the mycotoxin contribution from other feeds.
Aflatoxin
Major crops affected
Corn, corn silage, milo, sorghums, peanuts, and cottonseed
Associated mold
Aspergillus sp. (primarily Aspergillus flavus, A. nomius, and A. parasiticus)
Conditions favoring production
Heat and drought stress pre-harvest. Heat and humidity post-harvest
Symptoms
Primary target is the liver, resulting in abnormal blood clotting, jaundice, hemorrhaging, and reduced immune response. Affects rumen function in vitro and in vivo by decreasing cellulose digestion, volatile fatty acid formation, and proteolysis.
Acute: Inappetance, lethargy, ataxia, rough hair coat, and pale/enlarged fatty livers.
Chronic: Reduced feed efficiency and milk production, jaundice, decreased appetite, and reduced immune function.
FDA Action Levels
| For | Level (ppb) | Commodities |
| All animal species | 20 | All feed (exceptions below) |
| Breeding cattle, breeding swine, and mature poultry | 100 | Corn and peanuts |
| Finishing swine (>100 lbs.) | 200 | Corn and peanut products |
| Finishing beef cattle | 300 | Corn and peanut products |
| Beef cattle, swine, or poultry | 300 | Cottonseed meal |
| Immature animals | 20 | Animal feeds and ingredients, excluding cottonseed meal |
| Dairy animals, animals not listed above, or unknown use | 20 | Animal feeds and ingredients |
| Milk | <0.5 |
Vomitoxin (DON)
Major crops affected
Cereal grains and their corresponding silages
Associated mold
Fusarium sp.
Conditions favoring production
Wet, rainy and humid weather from flowering to harvest in corn and small grains. The results are Gibberella ear rot in corn or head blight in sorghum, barley, wheat, oats, and rye. Low temperatures following infection may increase DON production. DON can proliferate in stored grain with high moisture contents.
Symptoms
Digestive disorders (vomiting, diarrhea, reduced feed intake, & feed refusal); reduced feed efficiency, reduced weight gain or slowed growth; anorexia (DON increases the secretion of satiety hormones in the gastrointestinal tract, subsequently disturbing the levels of serotonin in the brain, & therefore leads to changes in appetite. Also, DON induces the up-regulation of pro-inflammatory cytokines, and with an increased concentration of cytokines in the brain leads to reduced feed intake.); depression; hemorrhages (stomach, heart, intestine, lung, bladder, & kidney); edema (inflammation); oral lesions; dermatitis; blood disorders (anemia & leukopenia); infertility & abortions; immunosuppression; and even mortality.
FDA Guidance Levels
| Class of animal | Feed & portion of the diet | DON levels in feed ingredients (ppm) | DON levels in total ration (ppm) |
| Ruminating beef and feedlot cattle older than 4 months | Grain and grain byproducts | 10 | 10 |
| Ruminating beef and feedlot cattle older than 4 months | Distillers grains, brewers grains, gluten meals, and gluten feeds derived from grains not to exceed 33% of total ration | 30 | 10 |
| Ruminating dairy cattle older than 4 months | Grain and grain byproducts not to exceed 50% of the diet | 10 | 5 |
| Ruminating dairy cattle older than 4 months | Distillers grains, brewers grains, gluten meals, and gluten feeds derived from grains not to exceed 17% of total ration | 30 ppm | 5 ppm |
| Chickens | Grain and grain byproducts not to exceed 50% of the diet | 10 | 5 |
| Swine | Grain and grain byproducts not to exceed 20% of the diet | 5 | 1 |
| All other animals | Grain and grain byproducts not to exceed 40% of the diet | 5 | 2 |
Zearalenone
Major crops affected
Cereal grains and their corresponding silages, corn (most frequently affected), and grains/silages that are late harvested and/or late maturing.
Associated mold
Fusarium sp.
Conditions favoring production
Cool and wet. After infestation of Fusarium mold, warm conditions promote more mold growth, while cool conditions promote more Zearalenone toxin formation. ZEA growth occurs more often in storage than in the field, in particular on high moisture grains that are questionable for storage.
Symptoms
Estrogenic effects - Irregular heats, low conception rates, ovarian cysts, atrophy of ovaries, pseudo pregnancy, malformation of fetus, embryonic loss, abortions, infertility, vulva edema, vaginitis, vaginal secretions, prolapses, enlarged &/or twisted uterus, reproductive tract infections, abnormal return to estrus, hyperestrogenism, stillbirths, fetal mummification, udder edema, teat enlargement, udder secretions, shrunken udder/agalactia, reduced feed intake, decreased milk production, milk contamination, reduced testicular size, delayed sexual maturity (male), low sperm production, tail necrosis (swine), splay-leg of piglets, and decreased litter size (swine).
T-2/HT-2
Major crops affected
Cereal grains and their corresponding silages
Associated mold
Fusarium sp.
Conditions favoring production
Cool and wet weather
Symptoms
Irritation, gastroenteritis, hemorrhages, and necrosis throughout the digestive tract; dermatitis, weight loss, poor feed utilization, lack of appetite, feed refusal, vomiting, bloody diarrhea, abortion, ulcers, decreased bone marrow production, immune suppression, and death (severe cases).
Fumonisin
Major crops affected
Corn
Associated mold
Fusarium sverticillioides (F.moniliforme), and Fusarium proliferatum
Conditions favoring production
Period of drought during the growing season followed by cool and moist conditions during pollination and kernel formation
Symptoms
Equine: Equine leukoencephalomalacia (ELEM –characterized by facial paralysis, nervousness, lameness, ataxia, and inability to eat or drink), depression, aimless wandering, incoordination, weakness, blindness, head-pressing, coma, death from brain necrosis.
Swine: Porcine pulmonary edema (PPE) – Dyspnea, cyanosis of mucous membranes, weakness, recumbency, liver damage (pale & fatty liver), pancreatic necrosis, kidney damage, icterus, increased water consumption, fever, immunosuppression, decreased performance, and death.
Cattle & Sheep: Inappetance, weight loss, mild liver damage (increase in liver enzymes), immunosuppression, and decreased milk production.
Poultry: Inappetance, weight loss, decreased performance, skeletal abnormalities, fatty liver, immunosuppression, inhomogeneous flocks, impaired feathering, and impaired intestinal health.
FDA Action Levels
| Class of animals | Corn and corn by-products (ppm) | Total ration (ppm) |
| Equids and rabbits | 5 | 1 |
| Swine and catfish | 20 | 10 |
| Breeding ruminants, breeding poultry, and breeding mink* | 30 | 15 |
| Ruminants > 3 months old being raised for slaughter, mink being raised for pelt production | 60 | 30 |
| Poultry being raised for slaughter | 100 | 50 |
| All other species or classes of livestock and pet animals | 10 | 5 |
| Includes lactating dairy cattle and hens laying eggs for human consumption | ||
Ochratoxin A
Major crops affected
Corn, barley, wheat, rye, and their associated silages.
Associated mold
Penicillium sp. and Aspergillus sp.
Conditions favoring production
Penicillium is a major silage mold and may be a greater silage problem because it can grow at lower pH than other molds. Considered to be more prevalent from a storage mold situation, rather than a field/growing condition mold situation.
Symptoms
Impaired kidney function/damage, liver damage (fatty liver), enteritis, necrosis of lymph nodes, and possibly blood in urine. Reduced feed intakes and performance. Inhibition of protein synthesis. Carcinogenic effects.
Fusaric acid
Major crops affected
Cereal grains and their corresponding silages.
Associated mold
Fusarium sp.
Conditions favoring production
Wet, rainy, and humid weather from flowering to harvest in corn and small grains.
Symptoms
Inhibits growth of rumen bacteria (anti-microbial), decreased microbial protein synthesis, lowers blood pressure, anemia, lower limb swelling/lameness, lethargy, reduced feed efficiency, feed refusal, udder edema, as well as many synergistic effects like vomiting and diarrhea, among other digestive disorders.
Trichothecene
(DAS, 3-Acetyl DON, 15-Acetyl DON, Nivalenol, and Fusarenon X)
Major crops affected
Cereal grains and their corresponding silages
Associated mold
Fusarium sp.
Conditions favoring production
Cool and wet weather
Symptoms
Digestive disorders (vomiting, diarrhea, gastroenteritis, hemorrhages, necrosis, ulcers, reduced feed intake, & feed refusal); reduced feed efficiency, reduced weight gain or slowed growth; anorexia, dermatitis, weight loss, depression, edema, blood disorders, oral lesions/irritations, infertility, immunosuppression, and even death (severe cases).
Citrinin
Major crops affected
Cereal grains and their associated forages.
Associated mold
Penicillium sp. and Aspergillus sp.
Conditions favoring production
Penicillium is a major silage mold and may be a greater silage problem because it can grow at lower pH than other molds.
Symptoms
Like Ochratoxin-A, Citrinin targets the kidneys. The primary toxic effect is the inhibition of protein synthesis. It has been shown to be a parasympathomimetic agent, causing necrosis of tubular epithelial cells in the kidney, and in some cases, hepatotoxicity, a chemically-driven liver damage condition. CTN is also known to have an antibacterial antibiotic effect. Teratogenic and carcinogenic.
Patulin
Major crops affected
Corn, barley, wheat, rye, their associated silages, and fruits.
Associated mold
Penicillium sp., Aspergillus sp., and Byssochlamys sp.
Conditions favoring production
Penicillium is a major silage mold and may be a greater silage problem because it can grow at lower pH than other molds.
Symptoms
Patulin is an antibiotic against gram-positive bacteria. In ruminants, Patulin has been shown to reduce VFA production, fiber digestion, and bacterial yield. Also, nephrotoxic (kidney) and immunotoxic effects. Gastrointestinal symptoms like gastric ulcers, intestinal hemorrhages, lesions in the duodenum, and alteration of intestinal barrier function.
Ergot
Major crops affected
Small grains, fescue, and other grasses
Associated mold
Claviceps
Conditions favoring production
Wet, cool, and cloudy during flowering.
Symptoms
The range of ergot contamination that can cause poisoning symptoms in cattle is between 0.1 and 0.3 percent (Ergot, 2012). Acute poisoning, which results from eating a large amount of ergot at one time, causes muscular trembling, lack of coordination, convulsions, and painful contraction of the muscles. In fatal cases, the animal becomes delirious. The gangrenous type of poisoning, which follows continued feeding on smaller amounts of ergot, causes the animal to become dull and depressed and to develop gangrene of the tail, feet, ears, or teats. Gangrene may vary from rather simple sores around the coronary band or top of the hoof, in the space between the claws, or on the teats, to a loosening of the hoof or the sloughing of a larger part of a limb or of the tail, ears, or teats. (Ergot, 2013)
FDA Levels
No action, advisory, or guidance levels have been established. Wheat or durum is graded as “ergoty” when it contains more than 0.05 percent by weight of ergot sclerotia; barley, oat, and triticale when they contain more than 0.1 percent by weight, and rye when it contains more than 0.3 percent. (University of Nebraska)
Prussic acid
Major crops affected
Sorghums, johnsongrass, white clover, vetch seed, chokecherry, and leaves of cherry trees. Plants have more potential for producing prussic acid if the soil is high in Nitrogen and deficient in phosphate and potassium.
Conditions favoring production
Plant cell damage caused by wilting, frosting, heat, drought, cool and cloudy weather, or herbicides can result in elevated levels of Prussic acid.
Symptoms
Prussic Acid is very potent and fast-acting. By interfering with oxygen use at a cellular level, it can cause asphyxiation and death in just a few minutes. Clinical signs occur rapidly and include excitement and muscle tremors, difficulty breathing, and convulsions. The characteristic sign of Prussic Acid toxicity is bright red color of the blood which can persist for several hours after death.
Treatment of Prussic Acid poisoning is possible if done very quickly. Consult a veterinarian for diagnosis and drug treatment because Prussic Acid poisoning is often confused with nitrate poisoning and other toxins of plant origin.
Sampling
To take a good sample for prussic acid testing:
-
Obtain fresh samples during the late morning or early afternoon. Glycoside levels typically increase in the morning and decrease in the afternoon and evening.
-
Collect random samples of several locations in a pasture or cores from several bales.
-
Seal in a plastic bag and store the sample in a dark and cold but not frozen container.
-
Deliver to the laboratory as soon as possible. Do not ship samples that will take multiple days to reach the lab.
Toxicity
The level of prussic acid required to cause toxicity varies depending on the rate of intake and individual animal tolerance. Generally, any forage with more than 200 ppm HCN on an as-fed basis is considered dangerous.
