Nursery Pig Feed Quality and Mycotoxin Management

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

Key Takeaways

• Nursery pigs are exceptionally vulnerable to mycotoxins due to their developing digestive and immune systems, immature detoxification pathways, and critical reliance on consistent feed intake; even low levels of toxins can cause significant growth retardation and immunosuppression.
• Mycotoxin contamination is insidious, often undetectable by sight or smell, necessitating routine laboratory testing of incoming grain and finished feed, particularly during high-risk harvest conditions like wet weather, to identify toxins such as aflatoxins, DON, zearalenone, fumonisins, and ochratoxin A.
• Feed quality issues beyond mycotoxins, including rancid fats, improper particle size, vitamin/mineral oxidation, and poor palatability, can mimic mycotoxin symptoms by reducing feed intake and performance, requiring a systematic troubleshooting approach that rules out these factors before focusing solely on toxins.
• Prevention of mycotoxin contamination is paramount, achieved through meticulous grain drying to appropriate moisture levels (≤15% for corn, ≤13.5% for small grains), clean storage facilities, controlled grain temperatures (ideally 40-50°F), moisture management within bins, and rapid feed turnover (within two weeks for nursery diets).
• Mycotoxin binders offer a risk management tool with variable efficacy, primarily binding aflatoxins and to a lesser extent zearalenone and fumonisins, but they cannot fully detoxify feed, restore nutrient value, or prevent all long-term organ damage, and should not replace proper sourcing, storage, and testing protocols.
• Establishing strict decision thresholds for feed intake drops (>10% for >24 hours), visible mold, and specific mycotoxin levels (e.g., DON >1 ppm, Aflatoxins >20 ppb) is crucial for timely intervention, with combination contamination requiring reduced acceptable levels for each toxin due to synergistic effects.

Feed quality is the single most controllable factor in nursery pig performance, yet it is often the last thing checked when pigs go off feed, scour, or fail to thrive. This guide covers the full scope of nursery pig feed quality and mycotoxin management, from the causes of contamination to step-by-step testing and prevention protocols. It is written for swine producers, farm managers, and feed handlers who need practical troubleshooting guidance they can apply immediately.

At a Glance

Understanding Mycotoxins in Pig Feed

Mycotoxins are toxic compounds produced by molds that grow on grains and feed ingredients. These molds are everywhere in the environment. They are present in soil, on living plants, and in stored grain. The key question is not whether molds are present, but whether conditions allowed them to grow and produce toxins before you fed the grain.

The molds that matter most for nursery pig feed quality produce toxins that damage the liver, kidneys, immune system, and digestive tract. The most common mycotoxins in swine feed include aflatoxins, deoxynivalenol (DON), zearalenone, fumonisins, and ochratoxin A. Each one comes from different mold species and causes different problems in pigs.

Aflatoxins come from Aspergillus molds and are most common in corn, peanuts, and cottonseed. They are potent liver toxins and carcinogens. In nursery pigs, aflatoxin contamination reduces feed intake, impairs weight gain, and suppresses immune function. Pigs affected by aflatoxins often look pale and unthrifty.

Deoxynivalenol, also called DON or vomitoxin, comes from Fusarium molds. It is one of the most common mycotoxins in corn and wheat in North America. DON causes feed refusal and vomiting, which is why it is so damaging in the nursery. Pigs will stop eating feed with even moderate DON contamination. The reduced feed intake alone can set a nursery group back by a week or more.

Zearalenone is another Fusarium toxin. It acts like estrogen and causes reproductive problems. In nursery pigs, zearalenone can cause swollen vulvas in gilts and reduced litter performance later in life. It does not usually cause obvious illness in young pigs, but it can create long-term reproductive damage that shows up months later.

Fumonisins come from Fusarium verticillioides and are common in corn. They damage the lungs and liver. In nursery pigs, fumonisins can cause pulmonary edema, which is fluid in the lungs. This condition can be fatal and is sometimes mistaken for a respiratory disease.

Ochratoxin A comes from Penicillium and Aspergillus molds. It damages the kidneys and suppresses immunity. Ochratoxin contamination is more common in barley and wheat than in corn. It tends to appear in stored grain that was not dried properly.

The challenge for producers is that mycotoxins often appear in combinations. A load of corn can contain both DON and fumonisins, or aflatoxins and zearalenone. Research and field experience show that combinations of mycotoxins can be more toxic than any single toxin at the same level. This additive or synergistic effect means you cannot simply check one toxin and assume the feed is safe.

How Mycotoxins Enter Nursery Pig Feed

Mycotoxin contamination can happen at any point from field to feeder. Understanding the entry points helps you build a prevention plan that covers every vulnerable step.

Field Contamination

Fusarium molds that produce DON and zearalenone infect corn and small grains while the plants are still growing. These are called field molds because they establish before harvest. Wet, cool weather during flowering and grain fill favors Fusarium infection. Drought stress followed by rain can also increase contamination. You cannot see these infections from the road. The grain can look perfectly normal and still carry significant toxin levels.

Corn ear rot caused by Fusarium is more visible. You may see pink or reddish mold on the ears when you walk fields before harvest. But the toxin distribution within a field is uneven. Some ears may be heavily contaminated while others are clean. This patchiness makes sampling critical.

Harvest and Handling Damage

Mechanical damage to grain kernels during harvest creates entry points for storage molds. Cracked kernels, broken kernels, and fines are more susceptible to mold growth than whole, intact kernels. Combine settings that crack grain, augers that grind kernels, and grain handling systems that create fines all contribute to the problem.

Harvest timing also matters. Grain harvested at high moisture and dried quickly can be safe. Grain that sits in the field through wet weather, or in the truck or wagon for days before drying, can develop mold before it ever reaches storage.

Storage Conditions

Storage molds, primarily Aspergillus and Penicillium species, grow when grain moisture and temperature are favorable. The safe moisture level for stored corn is 15 percent or lower for short-term storage and 13 to 14 percent for long-term storage. Small grains like wheat and barley need even lower moisture, around 13.5 percent or less.

Temperature is the other major factor. Mold growth slows at cooler temperatures but does not stop. Grain stored at 60 degrees Fahrenheit can support significant mold growth. Grain stored at 40 degrees Fahrenheit has much slower mold development. The warmer the grain, the faster molds can multiply and produce toxins.

Moisture migration within the bin is a common problem. Warm grain at the center of the bin can create condensation near the top and sides of the bin. This localized moisture can support mold growth even when the average grain moisture is safe. Proper aeration and regular bin checks catch these problems early.

Feed Mill and Delivery System Contamination

Finished feed can become contaminated in the mill, in bins, in augers, and in feeders. Feed that sits in bins for weeks gives molds time to grow. Feed that is exposed to moisture in leaking bins or condensation develops hot spots. Feed that remains in augers and feeders between batches can become a source of contamination for the next group of pigs.

The nursery is particularly vulnerable because feed is often delivered in smaller batches. A bin that is used for a nursery diet may hold feed for several weeks. If that feed was contaminated at the mill, or if the bin allows moisture in, the problem compounds over time.

Why Nursery Pigs Are Especially Vulnerable

Nursery pigs are the most sensitive animals on the farm to mycotoxins and feed quality issues for several reasons.

Their digestive systems are still developing. The switch from sow milk to solid feed is a major transition. The intestinal lining is immature, and the enzyme systems that help digest grain are not fully developed. Mycotoxins damage the intestinal lining and make it harder for pigs to absorb nutrients. This damage can persist long after the contaminated feed is removed.

Their immune systems are not fully functional. Maternal antibodies from colostrum decline in the first few weeks of life. The pig's own immune system takes time to mature. Mycotoxins suppress immune function, which means nursery pigs are more susceptible to the viral and bacterial challenges that are always present in the nursery.

Their feed intake is critical. Nursery pigs need to eat consistently to maintain growth and body temperature. Feed refusal caused by DON or poor palatability can quickly lead to weight loss, dehydration, and increased mortality. A pig that stops eating for even 24 hours loses momentum that is hard to recover.

Their liver and kidney detoxification systems are immature. Mycotoxins are processed and eliminated through the liver and kidneys. Young pigs have limited capacity to metabolize these toxins. The same level of contamination that an adult sow might tolerate can cause significant problems in a nursery pig.

Common Feed Quality Problems That Mimic Mycotoxin Issues

Not every feed problem in the nursery is caused by mycotoxins. Several other feed quality issues produce similar signs. Before you invest in mycotoxin testing, rule out these common problems.

Rancid Fats and Oils

Fats and oils in nursery diets can oxidize and become rancid. This happens when feed is stored too long, exposed to heat, or lacks adequate antioxidants. Rancid feed has a sharp, unpleasant odor and reduced palatability. Pigs will eat less of it. Rancid fats also destroy vitamins A, D, and E in the feed, which can lead to deficiency signs over time.

Check the fat sources in your nursery diets. Added fat should be fresh and stabilized with antioxidants. If you see reduced feed intake and the feed smells off, rancidity may be the cause.

Poor Particle Size

Nursery pigs do best with feed ground to a specific particle size. The recommended particle size for nursery pig feed is 500 to 700 microns. Feed that is ground too coarse reduces nutrient digestibility and increases feed wastage. Feed that is ground too fine can cause stomach ulcers and reduced intake.

If you recently changed grind settings, or if the feed looks different than usual, check particle size before suspecting mycotoxins.

Oxidation of Vitamins and Trace Minerals

Vitamins degrade over time. Vitamin C and some B vitamins are especially unstable. Trace minerals can interact with vitamins and fats in the feed, accelerating degradation. Feed that sits in bins for more than two weeks will have lower vitamin levels than fresh feed. This is usually not a problem in a healthy pig, but it can become one during stress or disease challenge.

Poor Palatability Ingredients

Some feed ingredients are less palatable than others. Certain protein sources, mineral premixes, and medications can reduce feed intake. If you recently changed the diet formulation or switched ingredient suppliers, palatability may be the issue.

Water Quality

Pigs that do not drink enough water will not eat enough feed. Water with high mineral content, bacterial contamination, or off flavors can reduce water intake. Check water lines, drinkers, and water quality before blaming the feed.

The key point is to keep an open mind. Mycotoxin contamination is a serious problem, but it is not the only cause of poor nursery performance. A systematic approach that rules out other causes will save you time and money.

Step-by-Step Troubleshooting for Suspected Mycotoxin Problems

When nursery pigs go off feed, scour, or fail to perform, work through this sequence to identify the cause.

Step 1: Observe and Document Signs

Write down what you see. Reduced feed intake is usually the first sign. Quantify it. Weigh feed remaining in feeders or track feed deliveries to determine how much consumption has dropped.

Look for vomiting, which is a classic sign of DON contamination. Check for diarrhea and note its color and consistency. Look at the pigs themselves. Are they pale, rough-haired, or unthrifty? Are there swollen vulvas in gilts, which suggests zearalenone?

Check mortality records. An increase in deaths, especially from respiratory distress or unexplained causes, can point to fumonisins.

Take photos. They help you track changes over time and provide documentation if you need to discuss the problem with a veterinarian.

Step 2: Rule Out Disease

Before you focus on feed, have a veterinarian examine the pigs. Several diseases cause the same signs as mycotoxin exposure. Porcine reproductive and respiratory syndrome, porcine epidemic diarrhea, and other viral and bacterial infections can reduce feed intake and cause diarrhea.

A veterinarian can perform necropsies on affected pigs and run diagnostic tests. These tests rule out infectious disease and help you focus on feed issues. Do not skip this step. Treating a feed problem while a viral disease runs through the nursery will not fix the problem.

Step 3: Inspect the Feed Visually

Look at the feed in the feeders and in the bins. Take a handful and examine it closely. Are there visible mold colonies? Mold can appear as white, gray, green, or pink fuzzy growth. Is there clumping or caking in the bin, which suggests moisture problems?

Smell the feed. Moldy feed often has a musty or earthy odor. Rancid feed has a sharp, unpleasant smell. But remember that mycotoxins can be present without any visible mold or off odor. Grain can be contaminated in the field and processed into feed that looks and smells normal.

Check the feeders. Are there stale feed accumulations in the corners? Is feed bridging in the feeder, preventing pigs from accessing fresh feed? Are there wet spots in the feeder from leaking drinkers?

Step 4: Check Feed Delivery and Storage Records

Trace the feed back to its source. When was it manufactured? What ingredients were used? Which mill produced it? When was it delivered to the farm?

Check the age of the feed in the bins. Nursery feed should be used within two weeks of manufacture. If feed has been sitting in a bin for a month or more, mold growth is more likely.

Check bin conditions. Are there leaks in the roof or sidewalls? Is condensate forming on the inside of the bin? When was the bin last cleaned? Old feed residue in bins can contaminate fresh feed.

Step 5: Collect Feed Samples for Testing

If you suspect mycotoxins, collect samples and send them to a laboratory for analysis. Sampling technique matters. A single handful from the top of a bin is not representative. You need a composite sample from multiple locations.

For bin sampling, use a grain probe to collect samples from several depths and locations. Combine these into one bag. Take at least a pound of feed for testing. For feeder samples, collect from several feeders and combine them.

Label each sample clearly with the date, location, and feed type. Keep a portion of the sample in case you need to confirm results or do additional testing.

Step 6: Interpret Test Results with the Right Thresholds

Mycotoxin test results come as parts per million or parts per billion. You need to compare these results to the appropriate thresholds for nursery pigs.

The U.S. Food and Drug Administration has established advisory levels for some mycotoxins in animal feed. For aflatoxins, the advisory level for finishing pigs is 200 parts per billion, but for young pigs, the level is much lower. The FDA advisory level for aflatoxins in feed for immature swine is 20 parts per billion.

For DON, the FDA advisory level for swine is 5 parts per million in grain and grain byproducts, but the recommendation is that these ingredients not exceed 40 percent of the diet. However, many swine nutritionists recommend much lower levels for nursery pigs. A common practical threshold for DON in nursery pig feed is 1 part per million. Some producers use even stricter limits of 0.5 parts per million for the youngest pigs.

There are no FDA advisory levels for zearalenone or fumonisins in swine feed. However, the National Pork Board and many university extension services recommend keeping zearalenone below 1 part per million in nursery feed and fumonisins below 5 parts per million. Some nutritionists recommend lower levels for nursery pigs.

The critical point is that these are guidelines, not guarantees. Individual pigs vary in their sensitivity. Stress, concurrent disease, and the presence of multiple mycotoxins all lower the level of contamination that causes problems.

Step 7: Take Corrective Action

If test results confirm mycotoxin contamination above safe levels, take immediate action.

Remove the contaminated feed. Replace it with fresh, clean feed from a trusted source. If you cannot confirm the feed source is clean, use a different supplier or ingredient source.

Clean the feeders and bins thoroughly. Remove all residual feed, sweep or vacuum the bins, and wash the feeders. Allow everything to dry completely before adding fresh feed.

Consider using a mycotoxin binder or detoxifier in the feed. These products contain ingredients like clay, yeast cell walls, or enzymes that bind mycotoxins in the digestive tract and reduce absorption. However, no binder removes all mycotoxins. Binders are most effective against aflatoxins and less effective against DON and other Fusarium toxins.

Work with your veterinarian or nutritionist to determine if a binder is appropriate for your situation. Do not rely on binders alone. They are a supplement to good feed management, not a replacement for it.

Step 8: Monitor the Pigs Closely

After you change feed, monitor the pigs carefully. Feed intake should improve within 24 to 48 hours if the problem was mycotoxin contamination. Pigs that were vomiting should stop. Diarrhea may take longer to resolve.

Track weight gain and mortality over the next two weeks. Some pigs may have permanent setbacks from the toxin exposure. Decide whether affected pigs need special care, such as extra heat, electrolytes, or a highly palatable diet to encourage intake.

Mycotoxin Testing Options and How to Use Them

Testing is the only reliable way to know if mycotoxins are present in your feed. The options range from quick on-farm tests to comprehensive laboratory analysis.

On-Farm Test Kits

Lateral flow test kits are available for several mycotoxins. These are similar to pregnancy tests. You mix a ground feed sample with a solution, apply it to the test strip, and read the result after a set time. These kits can detect aflatoxins, DON, zearalenone, and fumonisins.

The advantages of on-farm kits are speed and convenience. You get results in minutes without shipping samples to a lab. The disadvantages are lower accuracy and higher detection limits. On-farm kits are useful for screening, but they should not be the final word on feed safety.

Use on-farm kits to check incoming grain loads and to screen feed when you suspect a problem. If a screening test is positive, confirm the result with a laboratory analysis.

Laboratory Testing

Commercial laboratories offer quantitative testing for mycotoxins. The two main methods are ELISA and LC-MS/MS. ELISA is less expensive and works well for single toxins. LC-MS/MS can detect multiple mycotoxins in one test and is more accurate at low levels.

When you submit samples to a laboratory, specify which mycotoxins you want tested. A standard mycotoxin panel for swine feed typically includes aflatoxins, DON, zearalenone, fumonisins, and ochratoxin A. Some laboratories offer expanded panels that include additional toxins like T-2 toxin and ergot alkaloids.

Laboratory testing takes several days to a week. The cost depends on the number of toxins tested and the turnaround time. Routine monitoring of incoming grain is less expensive than an emergency investigation because you can test composite samples from multiple loads.

Sampling Protocol That Actually Works

The accuracy of any test depends on the quality of the sample. Mycotoxins are not evenly distributed in grain. A single contaminated kernel can raise the toxin level of a sample significantly. This patchiness means you must collect a representative sample.

For grain in a truck or wagon, take samples from multiple locations. Use a grain probe to reach below the surface. Collect at least five subsamples and combine them into one composite sample.

For grain in a bin, the challenge is getting a representative sample from different depths and locations. A grain probe can reach several feet into the bin. For deeper bins, consider using a vacuum sampler. Collect at least 10 subsamples from different locations.

For finished feed, collect samples from multiple bags or from multiple points in the bin. Grind the feed if it is pelleted or coarse. Mix the subsamples thoroughly, then take a smaller sample for submission.

Always use clean equipment when sampling. A probe or bucket contaminated with old feed can ruin your sample. Use new plastic bags for each sample.

How Often to Test

The frequency of testing depends on your risk level. In normal years with good harvest conditions, testing every load of incoming grain is expensive but provides the highest level of protection. Many producers test a percentage of loads, such as every third or fourth load, to keep costs manageable.

In wet harvest years or when you know mold pressure was high in the field, test every load. The cost of testing is far less than the cost of a nursery group that fails to perform.

Test finished feed when you change ingredient sources, when you see a performance problem, or when feed has been stored longer than normal. A quarterly testing program for finished feed is a reasonable baseline for most operations.

Preventing Mold Growth in Stored Feed

Prevention is always cheaper than treatment. A solid prevention program covers grain drying, storage conditions, bin management, and feed turnover.

Proper Grain Drying

Dry grain to the correct moisture content as soon as possible after harvest. For corn, dry to 15 percent moisture or lower for short-term storage. For storage beyond six months, dry to 13 to 14 percent. For small grains like wheat and barley, dry to 13.5 percent or lower.

Do not store wet grain even for a few days, thinking you will dry it later. Mold can begin growing within 24 to 48 hours in wet grain, especially in warm weather. The toxins produced during that time remain even after the grain is dried.

Clean Bins Before Filling

Never add new grain to a bin that contains old grain or residue. Old grain at the bottom of the bin can be contaminated with mold and insects. It can also harbor mycotoxins that will contaminate the new grain.

Clean bins thoroughly before filling. Sweep or vacuum all surfaces, including the walls, floor, and aeration ducts. Remove all dust and fines. Inspect for leaks, rust, and damage. Repair any problems before filling.

Manage Grain Temperature

Cool grain after harvest to stop mold growth. The goal is to bring grain temperature down to 40 to 50 degrees Fahrenheit for winter storage. Use aeration fans to pull cool, dry air through the grain.

Monitor grain temperature throughout storage. A rise in temperature in one area of the bin indicates mold growth or insect activity. Check grain temperature monthly during the winter and every two weeks during warmer months.

Control Moisture in the Bin

Moisture migration is a common cause of mold in stored grain. As the outside temperature drops in the fall, the center of the bin stays warm. Moisture moves from the warm center to the cooler edges and top, where it condenses. This condensation can create wet spots that support mold growth.

Run aeration fans in the fall to equalize grain temperature and reduce moisture migration. Check the top surface of the grain for crusting or wet spots. Break up any crust that forms and remove wet grain.

Practice First-In, First-Out Feed Management

Feed bins on the farm should operate on a first-in, first-out basis. Use the oldest feed first. Do not add new feed on top of old feed. This practice ensures feed does not sit in bins for extended periods.

The target is to use nursery feed within two weeks of manufacture. If you cannot meet this target, order smaller batches more frequently. Work with your feed supplier to coordinate delivery schedules.

Inspect Feeders Regularly

Feeders are a common source of stale, moldy feed. Feed accumulates in the corners of feeders and along the trough. Pigs may avoid this stale feed, but it can still contaminate fresh feed that is added on top.

Check feeders daily. Remove stale or moldy feed. Adjust feeder settings to minimize feed wastage and accumulation. Clean feeders thoroughly between groups of pigs.

Mycotoxin Binders and Detoxifiers: What Works and What Does Not

Mycotoxin binders are feed additives that claim to reduce the absorption of mycotoxins in the digestive tract. They work by binding to toxins and carrying them out in the feces. The effectiveness of these products varies widely by toxin and by product.

Clay-Based Binders

Bentonite, montmorillonite, and other clay products are the most common mycotoxin binders. They are effective at binding aflatoxins. The clay molecules have a structure that traps aflatoxin molecules and prevents their absorption.

Clay binders are much less effective against DON, zearalenone, and fumonisins. These toxins have different chemical structures that do not bind well to clay. Some studies show no benefit from clay binders against these toxins.

Yeast Cell Wall Products

Yeast cell wall products, particularly those derived from Saccharomyces cerevisiae, contain mannan-oligosaccharides and beta-glucans. These compounds can bind some mycotoxins, particularly zearalenone and fumonisins. The binding capacity is generally lower than clay for aflatoxins but broader across toxin types.

Enzyme-Based Detoxifiers

Some products contain enzymes that break down mycotoxins into less toxic compounds. These are more specific than binders. For example, certain enzymes can degrade DON into a less toxic metabolite. However, the effectiveness of these products in commercial pig production is still being studied.

What Binders Cannot Do

No binder removes all mycotoxins. No binder restores the nutritional value of contaminated feed. No binder prevents the long-term damage that mycotoxins cause to the liver, kidneys, and immune system.

Binders are a risk management tool, not a solution. They can reduce the impact of low to moderate contamination. They cannot make severely contaminated feed safe. If your test results show contamination above safe levels, discard the feed or divert it to a less sensitive animal class.

Choosing a Binder

If you decide to use a binder, choose a product with published research supporting its effectiveness against the specific mycotoxins you are concerned about. Ask the manufacturer for data from pigs, not just from laboratory tests. The binding capacity in a test tube does not always translate to protection in a live animal.

Work with your nutritionist to determine the correct inclusion rate. Adding too much binder can reduce nutrient absorption, particularly for vitamins and trace minerals. Some binders also bind medications, reducing their effectiveness.

Common Mistakes in Mycotoxin Management

Producers make several predictable mistakes when dealing with mycotoxin problems. Recognizing these mistakes can help you avoid them.

Mistake 1: Relying on Visual Inspection

The most common mistake is assuming that feed is safe because it looks and smells normal. Field molds that produce DON and zearalenone are invisible in harvested grain. The toxins they produce are colorless and odorless. You cannot see, smell, or taste mycotoxins. Only testing can confirm their presence or absence.

Mistake 2: Testing Only One Toxin

Another common mistake is testing for a single mycotoxin, usually aflatoxins, and concluding the feed is safe when that test is negative. Fusarium toxins like DON and zearalenone are more common in many regions than aflatoxins. A complete mycotoxin panel costs more but provides a complete picture.

Mistake 3: Using Inappropriate Thresholds

Producers sometimes compare test results to thresholds for finishing pigs or sows. Nursery pigs need much stricter limits. A DON level of 3 parts per million might be acceptable for finishing pigs but will cause significant feed refusal in nursery pigs. Always use thresholds appropriate for the age and sensitivity of the pigs you are feeding.

Mistake 4: Ignoring the Role of Storage

Some producers blame the field for mycotoxin contamination when the real problem was poor storage. Grain that was clean at harvest can develop significant mold and toxin contamination after weeks or months in a poorly managed bin. The source of the problem matters because the solution is different. Field contamination requires different grain sourcing. Storage contamination requires better bin management.

Mistake 5: Treating Symptoms Instead of the Cause

Adding a mycotoxin binder to contaminated feed can reduce the impact, but it does not fix the underlying problem. If your grain supply is consistently contaminated, you need to change your grain sourcing or improve your drying and storage practices. A binder is a bandage, not a cure.

Mistake 6: Not Documenting Problems

Producers who do not keep records of feed sources, test results, and pig performance find it difficult to identify patterns. If you do not know which loads of grain were contaminated, you cannot avoid them in the future. Keep a log of every feed delivery, including the source, date, and test results.

Mistake 7: Delaying Action

When pigs go off feed, every day of delay costs money. Pigs that do not eat do not grow. They also become more susceptible to disease. If you suspect mycotoxin contamination, test immediately. Do not wait to see if the pigs improve on their own.

Decision Thresholds for Nursery Pig Feed

Clear decision thresholds help you act quickly and consistently. Use these practical guidelines for nursery pig feed management.

Feed Intake Threshold

If feed intake drops by more than 10 percent from expected levels for more than 24 hours, investigate. Check water supply, feeder function, and pig health first. If those are normal, suspect feed quality and test the feed.

Visual Mold Threshold

If you see visible mold in feeders or bins, remove the affected feed immediately. Do not feed visibly moldy feed to nursery pigs. Send a sample for testing to determine if mycotoxins are present in the rest of the feed.

Mycotoxin Test Result Thresholds

Use these thresholds as starting points for nursery pig feed. Work with your veterinarian and nutritionist to adjust them for your specific situation.

These thresholds are conservative because nursery pigs are the most sensitive class of swine. The cost of discarding a batch of feed is usually less than the cost of a nursery group that fails to perform.

Combination Contamination Threshold

When multiple mycotoxins are present at low levels, the combined effect can exceed the effect of any single toxin. A practical rule is to reduce the acceptable level of each toxin by half when two or more toxins are present. For example, if DON is present at 0.5 parts per million and zearalenone is present at 0.5 parts per million, treat this as a higher risk than either toxin alone.

Monitoring and Recordkeeping for Feed Quality

A monitoring program for nursery pig feed quality does not need to be complicated, but it must be consistent. The goal is to catch problems early and to build a record that helps you identify patterns over time.

Daily Monitoring

Check feeders daily. Look for stale feed, mold, and wet spots. Note any changes in feed intake. Weigh or estimate feed disappearance each day. A sudden drop in intake is the earliest warning sign of a feed problem.

Check water flow and drinker function daily. Pigs that cannot drink enough water will not eat. Water intake and feed intake are closely linked.

Weekly Monitoring

Inspect feed bins weekly. Look for signs of condensation, crusting, or bridging. Check bin roofs and sidewalls for leaks. Note the amount of feed remaining and estimate how long it has been in the bin.

Check feed particle size weekly. A simple sieve test can tell you if the grind is within the target range. Consistent particle size is important for feed intake and digestibility.

Monthly Monitoring

Test finished feed monthly for mycotoxins. This is especially important if you source grain from multiple suppliers or if you have had contamination problems in the past. A monthly testing program provides a baseline that makes it easier to interpret results when problems occur.

Review pig performance data monthly. Track average daily gain, feed conversion, and mortality for each nursery group. Compare current groups to historical averages. A group that is underperforming may have a feed quality issue even if no other signs are present.

Recordkeeping System

Keep a log for each feed delivery. Record the date, feed type, mill or supplier, ingredient sources if known, and any test results. This log helps you trace problems back to their source.

Keep a log for each nursery group. Record the start date, number of pigs, feed consumption, average daily gain, feed conversion, and mortality. This log helps you identify patterns over time.

Keep all mycotoxin test results in a single file. Note the date, sample source, toxins tested, and results. Review this file regularly to identify seasonal patterns or recurring problems with specific suppliers.

When to Call a Veterinarian or Extension Agent

You do not need to manage feed quality problems alone. Several situations call for professional help.

Call a Veterinarian When

Call a veterinarian if pigs are dying, if you see signs of respiratory distress, or if diarrhea is severe or bloody. These signs can indicate infectious disease that requires immediate diagnosis and treatment. Do not delay veterinary involvement while you investigate feed issues.

Call a veterinarian if feed intake drops by more than 20 percent or if pigs are vomiting. A veterinarian can help you rule out disease and can advise on supportive care for affected pigs.

Call a veterinarian if you suspect fumonisin contamination. Pulmonary edema caused by fumonisins can progress quickly and is often fatal. A veterinarian can provide supportive care and help you confirm the diagnosis.

Call an Extension Agent or Nutritionist When

Call a swine extension specialist or a nutritionist if you need help interpreting mycotoxin test results. These professionals can help you determine whether the contamination level is safe for your specific pigs and can recommend appropriate actions.

Call an extension agent if you need help with grain storage or feed management. Extension services offer publications and workshops on grain drying, bin management, and mycotoxin prevention.

Call an extension agent if you need help developing a mycotoxin monitoring program. Many state extension services offer testing programs or can recommend accredited laboratories.

Call a Feed Mill or Supplier When

Call your feed supplier immediately if you suspect their feed is contaminated. The supplier needs to know about the problem so they can investigate their own processes and prevent future contamination. Ask for their testing records and for information about the ingredient sources in the affected feed.

If you source grain directly from farmers, contact the farmer if a load tests positive for mycotoxins. The farmer needs to know so they can test their remaining grain and adjust their storage or marketing plans.

Frequently Asked Questions

How quickly do nursery pigs show signs of mycotoxin contamination?

Feed refusal from DON can occur within hours of the pigs eating contaminated feed. Pigs that have been eating a contaminated diet may show reduced intake within the first day. Vomiting can occur within 24 hours at high contamination levels. Other signs like poor growth, diarrhea, and immune suppression develop over several days to weeks. The speed of onset depends on the toxin, the level of contamination, and the age and health of the pigs.

Can I feed moldy grain to nursery pigs if I add a mycotoxin binder?

No. Mycotoxin binders are not a substitute for feed quality. If grain is visibly moldy or tests above safe levels, do not feed it to nursery pigs. The binder will not remove all toxins, and the nutritional quality of moldy grain is already compromised. Discard the contaminated feed or divert it to a less sensitive class of livestock if the contamination level is within acceptable limits for that species.

What is the difference between mold and mycotoxins?

Mold is a visible fungus that grows on feed and grain. Mycotoxins are toxic compounds produced by molds. Not all molds produce mycotoxins, and mycotoxins can be present even when no mold is visible. Grain can be contaminated with mycotoxins in the field, then processed and stored in a way that prevents further mold growth. The toxins remain in the grain even though the mold that produced them is no longer active.

How often should I test my nursery pig feed for mycotoxins?

At minimum, test each new batch of finished nursery feed. If you source grain from multiple suppliers or if you are in a region with frequent mycotoxin problems, test more often. Test every load of incoming grain during wet harvest years. A monthly testing program for finished feed is a reasonable baseline. Increase testing frequency if you see performance problems or if you change ingredient sources.

What is the safe level of DON in nursery pig feed?

Most swine nutritionists recommend keeping DON below 1 part per million in nursery pig feed. Some recommend even lower levels of 0.5 parts per million for the youngest pigs. The FDA advisory level for DON in grain fed to swine is 5 parts per million, but this is for total grain in the diet and is not conservative enough for nursery pigs. At 1 part per million, some pigs may show reduced feed intake. At 2 parts per million, feed refusal is likely.

Can mycotoxins pass through the feed to affect farm workers?

Yes. Some mycotoxins can become airborne as dust when handling contaminated grain and feed. Aflatoxins are a known human health concern and are regulated as carcinogens. Workers who handle moldy grain should wear appropriate respiratory protection. Do not enter grain bins without proper safety equipment. The risks to human health are another reason to prevent mold growth and to handle contaminated feed carefully.

How do I collect a representative feed sample for mycotoxin testing?

Use a grain probe to collect samples from multiple locations and depths. For a truck or wagon, sample at least five locations. For a bin, sample at least 10 locations. Combine all subsamples into one composite sample and mix thoroughly. Take a portion of about one pound for submission to the laboratory. Use clean equipment and new plastic bags. Label the sample with the date, location, and feed type.

What should I do with contaminated feed that I cannot feed to pigs?

Options for disposing of contaminated feed depend on the toxin and the contamination level. Some contaminated grain can be blended with clean grain to dilute the toxin concentration, but this is risky and should only be done with professional guidance. Feed can sometimes be diverted to less sensitive species, such as beef cattle, if the contamination level is within safe limits for that species. Otherwise, dispose of the feed properly. Do not spread contaminated feed on fields where it could be consumed by wildlife or contaminate future crops.

Related Farming Guides

This section will be populated programmatically with related farming guides from the same knowledge base. Check back for links to companion articles on swine nutrition, nursery pig management, grain storage, and other related topics.

Related Clinical & Scientific Guides

• Pig Enrichment Programs and Behavior Monitoring
• Swine Handling Facility Design for Safe Pig Movement
• Swine Feeding Management for Grow-Finish Pigs

References

• National Pork Board: https://www.pork.org/
• USDA APHIS Swine Health: https://www.aphis.usda.gov/livestock-poultry-disease/swine
• FAO Pig Production: https://www.fao.org/pig-production-and-products/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.