Feed Testing for Mycotoxins in Livestock Feed

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Mycotoxins are toxic secondary metabolites produced by molds (Aspergillus, Fusarium, Penicillium genera) that contaminate livestock feed, causing reduced performance, immune suppression, reproductive issues, and mortality; they are often undetectable by sight or smell.
• Proactive testing is recommended for stressed crops, new feed sources, stored feed exceeding three months, and during weather conditions favoring mold growth; reactive testing is indicated by visible mold, unexplained performance drops, or disease incidence.
• Accurate sampling is paramount, requiring collection of multiple subsamples (10-20 for grain, multiple cores for forage) from various locations and depths, combined into a composite sample, to mitigate the heterogeneous distribution of mycotoxins.
• On-farm ELISA kits offer rapid screening, while laboratory methods like HPLC and LC-MS/MS provide higher accuracy and quantification for confirmatory analysis, with LC-MS/MS being the most comprehensive for detecting multiple toxins.
• Management strategies for contaminated feed include dilution with clean feed, use of binding agents (e.g., HSCAS for aflatoxins), physical sorting, and in severe cases, discarding the feed, with prevention through proper field management and storage being the most effective approach.
• Recordkeeping of test results, feed sources, and animal health observations is crucial for identifying trends, problem suppliers, and informing decisions on feed utilization, alongside consulting veterinarians for acute poisoning and extension agents for interpretation and management planning.

Mycotoxins are toxic compounds produced by certain molds that can contaminate livestock feed at any point from field to feed bunk. These toxins cause reduced performance, immune suppression, reproductive problems, and in severe cases, death. This guide explains how to test feed for mycotoxins, interpret results, and protect your herd or flock. It is written for livestock producers, farm managers, and feed handlers who need practical, actionable information on detecting and managing mycotoxin contamination.

At a Glance

• Test feed when you see visible mold, when animals show unexplained performance drops, or when weather conditions favor mold growth.
• Sample correctly. A poor sample gives misleading results no matter how good the laboratory is.
• Use ELISA test kits for quick on-farm screening and HPLC or LC-MS/MS for accurate laboratory confirmation.
• Test for the mycotoxins most relevant to your species. Cattle handle some toxins better than pigs or poultry.
• Store feed properly to prevent mold growth after testing. Testing only tells you what is in the feed at the time of sampling.
• Keep records of all test results, feed sources, and animal health observations.
• Call your veterinarian if animals show signs of acute mycotoxin poisoning. Call your extension agent for help interpreting results and planning next steps.

Understanding Mycotoxins in Livestock Feed

Mycotoxins are secondary metabolites produced by filamentous fungi, commonly called molds. These compounds are not essential for the mold's growth, but they serve as chemical defenses against competing organisms. The problem for livestock producers is that many of these compounds are toxic to animals at very low concentrations.

Molds that produce mycotoxins belong primarily to three genera: Aspergillus, Fusarium, and Penicillium. Each genus produces characteristic toxins under specific environmental conditions. Understanding which molds grow where helps you predict which mycotoxins might be present in your feed.

Aspergillus species produce aflatoxins, most notably aflatoxin B1. These molds thrive in warm, humid conditions and are common in corn, peanuts, cottonseed, and other oilseed crops. Aflatoxin B1 is among the most potent naturally occurring carcinogens known. It primarily affects the liver and suppresses the immune system. Dairy cattle excrete aflatoxin metabolites in milk, which creates a public health concern.

Fusarium species produce several important toxin groups including deoxynivalenol (DON, also called vomitoxin), zearalenone (ZEN), T-2 toxin, and fumonisins. These molds are common in temperate regions and infect crops in the field before harvest. Fusarium toxins are particularly problematic in corn, wheat, barley, and other small grains. Cool, wet weather during flowering and grain fill favors Fusarium infection.

Penicillium species produce ochratoxin A and citrinin. These molds typically contaminate stored grain and forages. They grow when feed is stored too wet, too warm, or for too long. Ochratoxin A primarily damages the kidneys and is most problematic in pigs.

The practical reality is that most contaminated feed contains multiple mycotoxins simultaneously. Molds do not grow alone, and different species often colonize the same feedstuff. The combined effect of multiple toxins can be additive or even synergistic, meaning the mixture is more toxic than the sum of its parts. This complicates risk assessment and makes testing for a single toxin insufficient.

Why Mycotoxin Testing Matters

Mycotoxin contamination is invisible in most cases. Moldy feed may look normal, smell normal, and taste normal to animals. The molds that produce toxins can be present without visible growth, and visible mold does not always mean toxins are present. You cannot reliably detect mycotoxins by sight, smell, or animal response alone.

The economic impact of mycotoxins goes far beyond acute poisoning events. Chronic low-level contamination causes:

• Reduced feed intake and weight gain
• Lower milk production
• Poor feed conversion efficiency
• Immune suppression leading to increased disease incidence
• Reduced reproductive performance
• Liver and kidney damage
• Increased veterinary and medication costs

These subclinical effects are often mistaken for other problems such as poor genetics, inadequate nutrition, or infectious disease. Testing is the only way to confirm whether mycotoxins are contributing to herd or flock problems.

Regulatory and market pressures also drive testing. Grain buyers, feed mills, and dairy processors increasingly require mycotoxin testing documentation. Export markets have strict limits on aflatoxin contamination. If you sell grain or feed, you need test results to prove compliance. If you feed your own livestock, testing helps you make informed decisions about whether to use, dilute, or discard contaminated feed.

When to Test Feed for Mycotoxins

You should test feed proactively and reactively. Proactive testing prevents problems before they occur. Reactive testing helps diagnose problems that are already affecting your animals.

Test proactively in these situations:

• When you harvest grain or forage from fields that experienced stress. Drought, excessive rainfall, insect damage, and hail all increase mold risk.
• When you purchase feed ingredients from new suppliers. Establish a baseline for the feeds you buy regularly.
• When you store feed for more than three months. Mycotoxins can develop during storage, especially in warm, humid conditions.
• When you change feed formulations or introduce new ingredients.
• When weather conditions during flowering, grain fill, or harvest favor mold development.

Test reactively when you see these signs:

• Visible mold in feed bunks, storage bins, or bales
• Unexplained drops in feed intake
• Reduced milk production or weight gain without other explanation
• Increased incidence of disease or poor response to treatment
• Reproductive problems such as poor conception rates or increased abortions
• Signs of acute poisoning such as vomiting, diarrhea, or neurological symptoms

The key is to test before you see problems in severe cases. By the time animals show clinical signs, you have already lost production and potentially animals. Routine testing of high-risk feeds is a management investment, not an expense.

Types of Mycotoxins to Test For

Different mycotoxins affect different species differently. Your testing program should target the toxins most relevant to your livestock.

Aflatoxins

Aflatoxins are produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin B1 is the most common and most toxic form. These toxins are hepatotoxic and carcinogenic. They also suppress immunity and reduce growth.

Species sensitivity varies. Pigs and young animals are highly sensitive. Cattle are more tolerant but excrete aflatoxin metabolites in milk. The FDA action level for aflatoxin in dairy feed is 20 parts per billion (ppb). Feed for breeding cattle can contain up to 100 ppb. Feed for finishing cattle can contain up to 300 ppb.

Aflatoxins are most common in corn, peanuts, cottonseed, and other warm-climate crops. Drought stress during grain development increases contamination risk.

Deoxynivalenol (DON or Vomitoxin)

DON is produced by Fusarium graminearum and related species. It is one of the most common mycotoxins in North American grain. DON inhibits protein synthesis and causes feed refusal and vomiting in pigs.

Pigs are the most sensitive species, with adverse effects seen at levels above 1 part per million (ppm). Cattle and poultry tolerate higher levels, but production can still suffer at levels above 5 ppm in cattle and 10 ppm in poultry.

DON is common in corn, wheat, barley, and other small grains. Cool, wet weather during flowering promotes infection.

Zearalenone (ZEN)

ZEN is also produced by Fusarium species. It has estrogenic activity that causes reproductive problems, especially in pigs. Clinical signs include swollen vulvas in gilts, reduced conception rates, and increased embryonic death.

Pigs are most sensitive, with effects seen at levels above 1 ppm. Cattle and poultry are less sensitive but can still experience reproductive issues at higher levels.

Fumonisins

Fumonisins are produced by Fusarium verticillioides and Fusarium proliferatum. These toxins are common in corn and corn-based feeds. Fumonisin B1 is the most important form.

Fumonisins cause pulmonary edema in pigs and leukoencephalomalacia in horses. In cattle, they cause liver and kidney damage at higher levels. The FDA guidance levels range from 5 ppm for horses and rabbits to 100 ppm for poultry.

T-2 Toxin

T-2 toxin is produced by Fusarium sporotrichioides and related species. It is highly toxic and causes severe gastrointestinal lesions, feed refusal, and immune suppression. Poultry and pigs are most sensitive. T-2 toxin is less common than DON but more toxic per unit of feed.

Ochratoxin A

Ochratoxin A is produced by Penicillium verrucosum and Aspergillus ochraceus. It primarily damages the kidneys. Pigs are the most sensitive species. This toxin is more common in stored grain and is associated with poor storage conditions.

Ergot Alkaloids

Ergot alkaloids are produced by Claviceps species that infect grasses and small grains. These toxins cause vasoconstriction that leads to reduced blood flow to extremities. Clinical signs include lameness, reduced weight gain, and in dairy cattle, reduced milk production and heat stress-like symptoms.

Ergot contamination is a growing concern in pastures and small grain production. Testing for ergot alkaloids requires specialized laboratory analysis.

Sampling Methods for Accurate Mycotoxin Testing

The accuracy of your test results depends almost entirely on the quality of your sample. Mycotoxins are not distributed evenly through feed. A single kernel of corn can contain high levels of toxin while the surrounding kernels are clean. This means you must collect a representative sample that reflects the average contamination level of the entire batch.

Sampling Grain and Ground Feed

For grain and ground feed, collect multiple subsamples from different locations in the batch. The goal is to collect at least 10 to 20 subsamples and combine them into one composite sample.

Follow these steps for whole grain:

1. Use a grain probe or sampling spear to collect samples from multiple depths and locations in the bin, truck, or railcar.
2. Sample from the top, middle, and bottom of the storage container.
3. Collect samples from the center and edges of the container.
4. Combine all subsamples in a clean bucket and mix thoroughly.
5. Use the quartering method to reduce the sample to a manageable size. Spread the mixed grain on a clean surface, divide it into four equal quadrants, and combine two opposite quadrants. Repeat until you have about 2 to 5 pounds of grain.
6. Place the final sample in a clean, labeled plastic bag or container.

For ground feed and complete rations, collect samples directly from the mixer, feed bunk, or delivery line. Take samples at regular intervals during mixing or unloading. Combine and mix these subsamples before taking your final sample.

Sampling Forages and Silage

Forage sampling presents additional challenges because mycotoxin contamination is often concentrated in specific areas. Moldy spots may be visible or hidden within the bale or silo.

For baled hay:

1. Use a hay probe to collect cores from multiple bales.
2. Sample at least 10 to 20 bales from the same lot.
3. Take cores from the ends and sides of each bale.
4. Combine cores and mix thoroughly.
5. Reduce the sample using the quartering method.

For silage:

1. Sample from the face of the silo or the pile after removing loose material.
2. Collect samples from multiple locations across the face.
3. Sample from top to bottom and side to side.
4. Avoid sampling spoiled surface material unless you want to test that specific material.
5. Combine samples and mix well.

Handling and Shipping Samples

Proper sample handling prevents mold growth during shipping, which would give you false results. Place samples in clean, airtight containers or heavy-duty plastic bags. Remove as much air as possible before sealing. Do not add preservatives unless the laboratory specifically requests them.

Label each sample clearly with:

• Your name and contact information
• Farm name and location
• Sample identification number
• Feed type and source
• Date of sampling
• Reason for testing

Ship samples to the laboratory as quickly as possible. Use overnight shipping for perishable samples like silage and high-moisture feeds. Keep samples cool but do not freeze them unless the laboratory instructs you to do so.

Laboratory Testing Methods

Several analytical methods are available for mycotoxin testing. Each has advantages and limitations. Your choice depends on your purpose, budget, and need for accuracy.

ELISA Test Kits

Enzyme-linked immunosorbent assay (ELISA) kits are the most common on-farm and on-site testing method. These kits use antibodies that bind specifically to target mycotoxins. They are available for all major mycotoxins and can detect multiple toxins in a single sample.

Advantages of ELISA kits:

• Quick results, typically within 15 to 30 minutes
• Relatively inexpensive per test
• Portable and usable on-farm
• No specialized laboratory equipment required
• Suitable for screening large numbers of samples

Disadvantages of ELISA kits:

• Lower accuracy than laboratory methods
• Results are semi-quantitative
• Cross-reactivity with related compounds can cause false positives
• Sensitivity varies by kit manufacturer
• Requires careful technique for reliable results

ELISA kits are best used for screening. If a screening test shows contamination near or above action levels, send a confirmatory sample to a laboratory for more accurate analysis.

High-Performance Liquid Chromatography (HPLC)

HPLC is a laboratory method that separates and quantifies individual mycotoxins. It is more accurate and precise than ELISA but requires specialized equipment and trained personnel.

Advantages of HPLC:

• High accuracy and precision
• Can quantify individual toxins
• Lower detection limits than ELISA
• Results are definitive and defensible

Disadvantages of HPLC:

• Expensive per sample
• Requires laboratory submission and shipping time
• Results take several days
• May require separate methods for different mycotoxin groups

Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS)

LC-MS/MS is the most advanced and comprehensive mycotoxin testing method. It can detect and quantify dozens of mycotoxins simultaneously in a single analysis. This is the preferred method for comprehensive mycotoxin panels.

Advantages of LC-MS/MS:

• Detects multiple mycotoxins in one run
• Very high accuracy and sensitivity
• Can detect emerging and modified mycotoxins that other methods miss
• Results are highly defensible

Disadvantages of LC-MS/MS:

• Most expensive option
• Requires specialized laboratory equipment
• Longer turnaround time
• May not be available at all laboratories

Near-Infrared Spectroscopy (NIR)

NIR is a rapid, non-destructive method that uses light absorption patterns to estimate mycotoxin levels. It is commonly used by grain elevators and feed mills for rapid screening of incoming ingredients.

Advantages of NIR:

• Very fast, results in seconds
• No sample preparation required
• Can test whole grain directly
• Low cost per sample

Disadvantages of NIR:

• Less accurate than chemical methods
• Requires calibration for each grain type and toxin
• May miss low-level contamination
• Best used as a sorting tool, not a definitive test

Choosing a Testing Strategy

For most livestock operations, a practical approach combines on-farm ELISA screening with laboratory confirmation. Use ELISA kits to screen incoming feed and to investigate suspected problems. When screening indicates contamination near action levels, send samples to a laboratory for HPLC or LC-MS/MS confirmation.

For routine monitoring of high-risk feeds, consider a comprehensive LC-MS/MS panel that covers all major mycotoxins. This gives you a complete picture of contamination and helps you identify mixed contamination that single-toxin tests would miss.

Interpreting Mycotoxin Test Results

Understanding test results requires knowing the regulatory guidance levels and the biological effects at different concentrations. The table below summarizes FDA advisory levels for major mycotoxins in different species.

Aflatoxin Guidance Levels

Deoxynivalenol (DON) Guidance Levels

Fumonisin Guidance Levels

These levels are guidance, not absolute safety thresholds. Animals vary in their sensitivity based on age, health status, and other stressors. Young animals, pregnant animals, and animals under stress are more susceptible to mycotoxin effects.

Action Thresholds for Decision Making

Use these general thresholds to guide your decisions:

For aflatoxins in dairy feed, any detection above 20 ppb requires immediate action. Do not feed contaminated feed to lactating dairy cows. The toxin passes into milk and creates a public health risk.

For aflatoxins in other livestock, contamination below 100 ppb may be acceptable for breeding stock with careful monitoring. Levels above 100 ppb require dilution or discard.

For DON in swine feed, levels above 1 ppm can cause feed refusal. Levels above 5 ppm cause vomiting and require immediate action.

For zearalenone in breeding swine, levels above 1 ppm can cause reproductive problems. Levels above 3 ppm cause severe reproductive issues.

For fumonisins in horses, any level above 5 ppm is dangerous and can cause fatal brain disease.

These thresholds are starting points. Work with your veterinarian or extension specialist to interpret results for your specific situation.

Common Mistakes in Mycotoxin Testing

Many producers make errors that compromise the value of their testing program. Avoid these common mistakes.

Mistake 1: Testing a Poor Sample

The most common mistake is submitting a sample that does not represent the feed batch. A single handful of grain or a single core from a hay bale tells you almost nothing about the whole batch. Mycotoxins are highly heterogeneous, meaning they concentrate in hotspots. You must collect multiple subsamples and combine them properly.

Mistake 2: Testing Only for One Toxin

Many producers test only for aflatoxin because it is the most well-known mycotoxin. This misses the reality that Fusarium toxins like DON and zearalenone are much more common in many regions. A comprehensive test panel is more expensive but provides a complete picture. The cost of missing a contamination problem far exceeds the cost of comprehensive testing.

Mistake 3: Ignoring Visible Mold

Some producers see visible mold and assume the feed is contaminated, while others see no mold and assume the feed is clean. Both assumptions are wrong. Visible mold does not always mean toxins are present, and toxin contamination can occur without visible mold. Test any feed that looks suspicious, and test feed that performs poorly even if it looks clean.

Mistake 4: Sampling Only at Harvest

Mycotoxin levels can change dramatically during storage. Properly stored feed can develop mold and toxins over time, especially if moisture levels are too high or temperatures fluctuate. Test feed at harvest, again before feeding, and periodically during long-term storage.

Mistake 5: Not Recording Results

Test results are only useful if you can use them to make decisions and track trends over time. Keep a log of all test results, including the date, feed source, sample location, and results. This helps you identify suppliers or storage conditions that consistently produce contaminated feed.

Mistake 6: Confusing Screening and Confirmatory Tests

ELISA screening tests are useful for quick decisions but are not definitive. A positive screening result should be confirmed with a laboratory method before you discard feed or take other drastic action. Conversely, a negative screening result does not guarantee the feed is clean. Screening tests have detection limits and can miss low-level contamination.

Mistake 7: Not Considering Multiple Mycotoxins

Feed can contain several mycotoxins at levels that are individually safe but collectively harmful. The additive and synergistic effects of multiple toxins are well documented. If you only test for one or two toxins, you may miss the combined effect.

Managing Mycotoxin Contamination in Feed

When test results confirm contamination, you have several management options. Your choice depends on the toxin, the level, the species being fed, and the availability of alternative feed.

Dilution with Clean Feed

Dilution is the most common approach for managing low to moderate contamination. Mix contaminated feed with clean feed to reduce the toxin concentration below action levels. This works well when contamination levels are not extreme and clean feed is available.

Calculate the dilution ratio based on the toxin level in the contaminated feed and the target level in the final ration. For example, if corn contains 100 ppb aflatoxin and you need to feed dairy cows at 20 ppb or less, mix one part contaminated corn with four parts clean corn. This gives a final concentration of 20 ppb.

Dilution has limits. It does not remove toxins, it only reduces concentration. It also requires that you have enough clean feed to achieve the target dilution. In severe contamination, dilution may not be practical.

Binding Agents and Feed Additives

Several products claim to bind mycotoxins in the digestive tract and reduce absorption. These include clay products like bentonite and hydrated sodium calcium aluminosilicate (HSCAS), yeast cell wall products, and activated charcoal.

Clay binders are most effective against aflatoxins. They have limited effectiveness against DON and zearalenone. Yeast cell wall products, particularly those containing esterified glucomannan, have broader binding activity but are less consistent.

Use binding agents as a management tool, not a solution. They do not eliminate toxicity, they only reduce absorption. They are most useful for low-level contamination when combined with other management measures.

Sorting and Cleaning

For whole grain, physical sorting and cleaning can remove contaminated kernels. Mycotoxin contamination is often concentrated in broken kernels, shriveled kernels, and fines. Screening and aspiration remove these lighter, damaged kernels and reduce toxin levels.

Gravity separators and color sorters are more effective but require specialized equipment. These are more practical for commercial grain operations than for individual farms.

Ensiling and Fermentation

Some mycotoxins degrade during ensiling, but others are stable. Aflatoxins are highly stable and do not degrade significantly during ensiling. DON is relatively stable. Zearalenone can be reduced by fermentation but is not eliminated.

Do not assume ensiling solves a mycotoxin problem. Test silage after fermentation to confirm toxin levels.

Discarding Contaminated Feed

In severe contamination, the only safe option is to discard the feed. This is costly but may be necessary to protect animal health and avoid regulatory problems. The decision to discard should be based on the toxin level, the species being fed, and the potential consequences of feeding contaminated feed.

For dairy cattle with aflatoxin contamination above 20 ppb, discarding is the only safe option. The toxin passes into milk and creates a public health risk that could lead to regulatory action and loss of market access.

Segregating Contaminated Feed

If you must use contaminated feed, segregate it for use in less sensitive animals. For example, feed contaminated corn to finishing cattle rather than dairy cows or breeding stock. This reduces risk to the most sensitive animals while still using the feed.

Preventing Mycotoxin Contamination

Prevention is more effective and less costly than dealing with contamination after it occurs. Focus on prevention at every stage from field to feed bunk.

Field Prevention

Choose crop varieties with resistance to Fusarium and Aspergillus infection. Plant at recommended dates and populations to reduce stress. Manage irrigation to avoid drought stress during grain fill. Control insects that damage grain and create entry points for molds.

Harvest at the correct moisture content and maturity. Delayed harvest increases exposure to field molds and insects. Adjust combine settings to minimize kernel damage and fines.

Storage Management

Proper storage is critical for preventing mold growth and mycotoxin production. Clean bins thoroughly before filling. Remove old grain and debris that can harbor mold spores.

Dry grain to the recommended moisture content. For corn, this is 15 percent for short-term storage and 13 percent for long-term storage. For soybeans, this is 13 percent for short-term and 11 percent for long-term. Small grains should be dried to 13.5 percent or lower.

Cool grain after drying to prevent moisture migration and condensation. Aerate bins to maintain uniform temperature and moisture. Monitor grain temperature and moisture regularly during storage. Inspect bins for leaks and repair them promptly.

Feed Management

Use a first-in, first-out inventory system to avoid feeding stale feed. Do not store feed for longer than necessary. Clean feed bins and delivery equipment regularly.

Minimize feed accumulation in bunks and troughs. Remove uneaten feed and clean feeding areas to prevent mold growth. Protect feed from moisture and pests.

Forage Management

For hay, bale at the correct moisture content. Hay baled too wet will heat and mold. Store bales off the ground and protect them from rain and ground moisture.

For silage, pack thoroughly to exclude oxygen, cover promptly, and seal the silo or pile properly. Use a good inoculant to promote rapid fermentation. Feed out silage at an adequate rate to prevent spoilage at the face.

Monitoring and Recordkeeping

A comprehensive mycotoxin monitoring program includes regular testing, animal observation, and detailed recordkeeping.

Establish a Testing Schedule

Develop a testing schedule based on your risk level. High-risk operations should test every load of incoming grain and every batch of mixed feed. Lower-risk operations can test monthly or quarterly.

Test at these critical points:

• At harvest for all stored grain and forage
• Before feeding new batches of purchased feed
• Monthly during long-term storage
• Immediately when you suspect a problem

Track Animal Performance

Monitor feed intake, weight gain, milk production, and reproductive performance. Sudden changes in any of these parameters may indicate mycotoxin contamination. Keep records of these parameters so you can identify trends and detect problems early.

Watch for these signs of mycotoxin exposure:

• Reduced feed intake within 24 to 48 hours of feeding a new batch
• Reduced milk production within 3 to 7 days
• Increased incidence of disease or poor response to treatment
• Reproductive problems such as poor conception or increased abortions
• Vomiting or diarrhea, especially in pigs
• Swollen vulvas in gilts

Maintain Detailed Records

Keep a mycotoxin testing log that includes:

• Date of sampling
• Feed type and source
• Sample location
• Laboratory and test method
• Test results for each mycotoxin
• Action taken based on results
• Animal health observations

These records help you identify problem suppliers, problem feed sources, and seasonal patterns. They also provide documentation if you need to make a claim against a feed supplier or defend your management decisions.

When to Call a Veterinarian or Extension Agent

Mycotoxin testing and management often require professional assistance. Know when to seek help.

Call Your Veterinarian Immediately If:

• Animals show acute signs of poisoning such as severe vomiting, diarrhea, neurological symptoms, or sudden death
• Multiple animals become ill simultaneously
• You suspect aflatoxin contamination in dairy feed, which poses a public health risk
• Animals do not respond to treatment for suspected infectious disease
• You see reproductive problems such as abortions or stillbirths

Your veterinarian can help diagnose mycotoxin poisoning, provide supportive treatment, and advise on the safe use of contaminated feed.

Call Your Extension Agent When:

• You need help interpreting test results
• You are deciding whether to use, dilute, or discard contaminated feed
• You need guidance on sampling procedures
• You want to develop a monitoring program for your operation
• You need information on local mycotoxin risk and prevention strategies

Extension agents have access to specialists in plant pathology, animal nutrition, and veterinary medicine. They can help you navigate complex decisions and connect you with laboratory services.

Call Your Feed Supplier When:

• Purchased feed tests above guaranteed levels
• You suspect a specific load or batch is contaminated
• You need certificates of analysis for incoming feed
• You have questions about feed ingredient sourcing

Document all communications with suppliers. If you have a legitimate claim, you need evidence of the contamination and the communication history.

Frequently Asked Questions

How often should I test my livestock feed for mycotoxins?

Test every load of high-risk feed ingredients such as corn, wheat, and cottonseed. Test mixed feed at least monthly if you use a consistent formulation. Test forages at harvest and again before feeding if they will be stored for more than three months. Increase testing frequency during years with weather conditions that favor mold development, such as drought, excessive rainfall, or cool wet conditions during flowering and grain fill.

Can I test feed for mycotoxins on my farm without sending samples to a laboratory?

Yes, you can use ELISA test kits for on-farm screening. These kits provide results in 15 to 30 minutes and are available for all major mycotoxins. They are less accurate than laboratory methods but are useful for quick decisions and routine monitoring. When screening results are near action levels, send a confirmatory sample to a laboratory for HPLC or LC-MS/MS analysis.

What is the difference between mold count and mycotoxin testing?

Mold count measures the number of mold organisms in a feed sample. Mycotoxin testing measures the concentration of specific toxic compounds. Mold count and mycotoxin level do not always correlate. Feed with high mold counts may have low toxin levels, and feed with no visible mold can contain significant toxins. Mycotoxin testing is more directly relevant to animal health.

How much does mycotoxin testing cost?

Costs vary by test method and laboratory. ELISA screening kits cost roughly 15 to 40 dollars per test. HPLC analysis costs 50 to 150 dollars per sample for individual toxins. Comprehensive LC-MS/MS panels that test for 30 or more mycotoxins cost 100 to 250 dollars per sample. The cost of testing is small compared to the potential losses from feeding contaminated feed.

What should I do if my feed tests positive for aflatoxin?

Stop feeding the contaminated feed immediately. Confirm the result with a laboratory test if you used an ELISA screening kit. For dairy cattle, feed containing more than 20 ppb aflatoxin must not be fed because toxin passes into milk. For other species, compare the test result to FDA guidance levels and decide whether to dilute, treat with binders, or discard. Contact your veterinarian and extension agent for guidance.

Can mycotoxins be destroyed by heat treatment or processing?

Some mycotoxins are partially degraded by heat, but most are highly stable. Aflatoxins survive normal feed processing temperatures. DON and fumonisins are also heat-stable. Extrusion and pelleting may reduce some toxin levels but do not eliminate them. Ammoniation can reduce aflatoxin levels in some feedstuffs but is not approved for all applications and does not affect other mycotoxins. Do not rely on processing to solve a contamination problem.

What are the signs of mycotoxin poisoning in cattle?

Cattle exposed to mycotoxins may show reduced feed intake, decreased milk production, poor weight gain, diarrhea, immune suppression, and reproductive problems. Aflatoxin specifically causes liver damage, jaundice, and reduced feed efficiency. Ergot alkaloids cause reduced blood flow to extremities, leading to lameness, swollen feet, and heat intolerance. Fumonisins can cause liver and kidney damage at higher levels.

How do I collect a representative sample from a large grain bin?

Use a grain probe or sampling spear to collect samples from multiple depths and locations. Sample the top, middle, and bottom of the bin. Collect from the center and edges. Take at least 10 to 20 subsamples and combine them in a clean bucket. Mix thoroughly and reduce the sample using the quartering method until you have 2 to 5 pounds of grain for submission to the laboratory.

Related Farming Guides

• Feed Testing for Mycotoxins: When and How to Test

This section will be populated with links to related farming guides on feed management, livestock nutrition, and animal health topics. Check back for updated content.

Related Clinical & Scientific Guides

• Animal Welfare Audits: Building a Useful Farm Program
• Total Mixed Ration (TMR) for Dairy: Mixing and Feeding Management
• Feed Additives for Livestock: Probiotics, Enzymes, and More

References

• USDA Farm Management: https://www.farmers.gov/
• FAO Farm Management: https://www.fao.org/farmer-field-schools/en/
• FAO Animal Production and Health: https://www.fao.org/animal-production/en/
• WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.