Pig Feed Storage and Mycotoxin Prevention

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

Key Takeaways

Moisture and Temperature are Primary Drivers of Mold: Mold growth, leading to mycotoxin production, is critically dependent on feed moisture content (ideally below 13% for grain, 12% for mash) and temperature (optimal growth between 77-86°F, but some species grow at lower temperatures).
Mycotoxins are Stable and Irreversible: Mycotoxins are heat-stable compounds that are not destroyed by grinding, pelleting, or cooking, making prevention through proper storage the only effective strategy; blending moldy feed with good feed does not dilute toxins and is a critical error.
Early Detection and Monitoring are Crucial: Regular visual and olfactory inspection at all feed transfer points, coupled with weekly temperature checks (a 5-10°F rise above ambient indicates mold activity), are essential for early detection of spoilage.
First-In, First-Out (FIFO) Rotation Minimizes Risk: Implementing a strict FIFO system, aiming for feed turnover within two to four weeks in summer, prevents prolonged storage which significantly increases the opportunity for mold proliferation and toxin accumulation.
Breeding Stock Require Stricter Thresholds: Reproductive animals are more susceptible to mycotoxins, particularly Zearalenone; feed exhibiting any visible mold, off-odors, or exceeding conservative mycotoxin action levels (e.g., 20 ppb Aflatoxin, 1 ppm DON for finishing pigs, but lower for breeding stock) should not be fed to them.
Comprehensive Recordkeeping and Professional Consultation are Vital: Maintaining detailed records of feed deliveries, storage conditions, and test results, alongside consulting veterinarians or extension agents for signs of mycotoxin exposure or when feed quality is questionable, ensures proactive herd health management.

Stored pig feed is a living system. Moisture, temperature, and time work together to determine whether your feed stays nutritious or becomes a source of hidden losses. This guide covers the full process of protecting feed from spoilage and mold, from bin selection and moisture control to monitoring programs and knowing when to call for professional help. It is written for pig farmers, farm managers, and employees who handle feed on a daily basis and need practical steps to protect herd health and feed investment.

At a Glance

Keep feed moisture below 13 percent in stored grain and below 12 percent in finished mash feed.
Clean bins and storage areas completely before adding new feed.
Use a first in, first out rotation system so feed never sits longer than two to four weeks in summer.
Check feed temperature weekly. A rise of 5 to 10 degrees Fahrenheit above ambient temperature signals mold activity.
Inspect feed visually and by smell at every transfer point from delivery to feeder.
Test suspect feed for mycotoxins before feeding it to any pig, especially breeding stock.
Never blend moldy feed with good feed to dilute it. This does not eliminate toxins.
Keep all storage areas dark, dry, and cool. Light, heat, and moisture are the three enemies of feed quality.
Call your veterinarian or extension agent immediately if pigs show signs of mycotoxin exposure such as reduced feed intake, poor growth, or reproductive problems.

Understanding Feed Spoilage and Mycotoxins

Feed spoilage is not a single event. It is a process driven by microorganisms, mostly molds, that break down feed components and produce waste products. Some of these waste products are toxic to pigs. These toxins are called mycotoxins, and they are the main reason feed storage deserves serious attention.

What Causes Feed to Spoil

Molds are fungi that grow on organic material. They are everywhere in the environment. They exist as spores in the air, on surfaces, and in soil. When conditions are right, these spores germinate and grow. The conditions that favor mold growth in pig feed are well understood.

Moisture is the most important factor. Molds need water to grow. In stored feed, the relevant measure is water activity, which is the amount of water available for microbial use. Feed with a moisture content above 13 percent creates conditions where molds can multiply. Finished feed with moisture above 12 percent is at increased risk.

Temperature is the second critical factor. Most feed molds grow best between 77 and 86 degrees Fahrenheit. However, they can grow at much lower temperatures. Some species, like Fusarium, grow at temperatures as low as 40 degrees Fahrenheit. This means mold is not just a summer problem. In many climates, mold can develop during any season if moisture is present.

Oxygen is the third requirement. Most molds that affect stored feed need oxygen to grow. This is why proper packing and sealing can help. However, some molds can grow in low-oxygen environments, and damaged storage structures can let in air.

Time is the final factor. Even with favorable moisture and temperature, mold takes time to become a problem. Feed stored for short periods is at lower risk. Feed stored for months is at higher risk. The longer feed sits, the more opportunity mold has to establish and produce toxins.

The Main Mycotoxins That Affect Pigs

Several mycotoxins are particularly important in pig production. Each comes from different mold species and causes different problems.

Aflatoxins are produced by Aspergillus molds. These are among the most toxic mycotoxins. Aflatoxin B1 is the most common and most dangerous form. It causes liver damage, reduces feed intake, and suppresses the immune system. Pigs exposed to aflatoxins grow poorly and are more susceptible to other diseases. At high levels, aflatoxins can cause death.

Deoxynivalenol, commonly called DON or vomitoxin, is produced by Fusarium molds. It gets its nickname from its effect on pigs. Pigs that consume DON refuse feed and may vomit. Even low levels reduce feed intake and weight gain. DON is one of the most common mycotoxins found in pig feed in North America.

Zearalenone is also produced by Fusarium molds. It has estrogen-like effects on pigs. In gilts and sows, it causes swelling of the vulva, enlarged uterus, and reproductive problems. In young gilts, it can cause signs that look like early puberty. In boars, it reduces fertility. Zearalenone is especially damaging to breeding herds.

Ochratoxin is produced by Penicillium and Aspergillus molds. It damages the kidneys and reduces growth. It can accumulate in the body over time, making chronic exposure a serious concern.

Fumonisins are produced by Fusarium molds. They affect the lungs and liver in pigs. They can cause pulmonary edema, which is fluid in the lungs, and can be fatal at high levels.

T-2 toxin is produced by Fusarium molds. It causes severe irritation to the mouth and digestive tract. Pigs may refuse feed, vomit, and show bloody diarrhea.

How Mycotoxins Enter the Feed Supply

Mycotoxins can enter the feed supply at any point from field to feeder. Understanding these entry points helps you build a defense at each stage.

In the field, molds infect growing grain. Fusarium species are common field molds. They infect corn, wheat, and other grains while the plants are still growing. Weather stress, insect damage, and delayed harvest all increase field mold contamination.

At harvest, grain with high moisture content is at risk. If grain is harvested too wet and not dried quickly, molds can grow during storage. Damaged or broken kernels are especially vulnerable because they provide easy entry points for mold.

During storage, moisture migration and temperature changes can create pockets of condensation. These wet spots become mold factories. Improperly cleaned bins and storage structures harbor old feed and dust that contain mold spores.

In the feed mill or on the farm, finished feed can become contaminated through mixing equipment, augers, and bins that are not cleaned between batches. Moisture can enter through leaks in roofs, poorly sealed bins, and condensation on metal surfaces.

During delivery and feeding, feed that sits in feeders for extended periods can mold. Pigs that root and play in feeders can contaminate feed with saliva and moisture. Feed that is not consumed quickly becomes a mold risk.

Why Mycotoxin Prevention Matters More Than Treatment

Mycotoxin problems are difficult to treat once they occur. Mold can be killed, but the toxins remain. Mycotoxins are stable compounds. They survive heat, freezing, and many processing steps. Cooking moldy feed does not make it safe. Grinding, pelleting, and extruding do not destroy mycotoxins.

This means prevention is the only reliable strategy. You cannot fix a mycotoxin problem after the feed is contaminated. You can only avoid feeding contaminated feed and prevent contamination from happening in the first place.

The economic impact of mycotoxins goes beyond the feed itself. Reduced feed intake means slower growth and longer time to market. Reduced immune function means more disease and higher veterinary costs. Reproductive problems mean fewer pigs born and lower herd productivity. All of these losses are hidden in the sense that they are not always obvious at first. A pig that eats slightly less feed every day may not look sick, but the lost gain adds up over weeks and months.

Assessing Your Current Feed Storage Setup

Before you can improve your feed storage, you need to know what you have. A thorough assessment of your current setup identifies weak points and priorities for improvement.

Types of Feed Storage Systems

Pig farms use several types of feed storage systems. Each has advantages and disadvantages for mold prevention.

Feed bins are the most common storage for finished feed on pig farms. They are typically made of metal or plastic and range in size from a few tons to 20 tons or more. Good bins are sealed against moisture and pests. They have a cone-shaped bottom that allows feed to flow out by gravity. They should be equipped with aeration or at least good ventilation at the top.

Grain bins store raw grain before it is ground and mixed. These are larger structures, often made of steel. They should have aeration systems to control moisture and temperature. Proper grain bin management is essential because mycotoxins that start in stored grain continue into the finished feed.

Gravity wagons and hopper trailers are used for short-term storage and transport. They are not designed for long-term storage. Feed should move through them quickly.

Bagged feed is used on some farms, especially for small operations or specialty feeds. Bags protect feed from moisture and pests but only if they remain intact. Torn bags are a major risk.

Grain bags, also called ag bags, are long plastic tubes used for storing grain. They are popular in some regions for their low cost. They require careful management to prevent moisture entry.

Evaluating Your Storage Facilities

Walk through your feed storage areas and look for the following risk factors.

Check the condition of bins and structures. Look for rust, holes, and gaps. A small hole in a bin can let in rain and pests. Check the seals around lids and openings. Look for signs of previous water entry, such as rust streaks or staining.

Check the condition of the ground around bins. Water should drain away from bins, not toward them. Bins on low ground or in areas that flood are at high risk.

Check the aeration system. Are fans working? Are air ducts clear? Can you feel air movement when the system runs? Aeration is your main tool for controlling moisture and temperature in stored grain.

Check the condition of augers, conveyors, and other feed handling equipment. Cracks and gaps in these systems can hold old feed that molds and contaminates new feed.

Check the condition of feeders in pig pens. Do they have areas where feed can sit and collect moisture? Are they designed to minimize feed waste and moisture entry?

Check the area around feed storage for birds, rodents, and insects. These pests damage feed and introduce moisture and mold spores.

Calculating Your Storage Needs

The amount of feed storage you need depends on your operation size and delivery schedule. As a general rule, you should not store more feed than you can use in two to four weeks. Longer storage increases mold risk.

For a farrow to finish operation, calculate your daily feed use and multiply by the number of days you want to store feed. This gives you the minimum storage capacity you need. Add a small buffer for delivery delays, but do not overbuild. Excess storage capacity encourages keeping feed too long.

For raw grain, the calculation is different. You may need to store grain for many months between harvest and use. In this case, focus on proper drying and aeration rather than quick turnover.

Identifying High Risk Times

Some times of year are higher risk for feed spoilage than others. Plan your monitoring and management accordingly.

Summer is high risk because of heat and humidity. Warm temperatures accelerate mold growth. High humidity increases the moisture content of feed exposed to air. Summer is the time when feed should turn over fastest.

Fall is high risk at harvest. Wet grain and delayed harvest create conditions for field molds. Freshly harvested grain must be dried quickly and monitored carefully.

Winter is moderate risk. Cold temperatures slow mold growth, but condensation can be a problem. Temperature changes between day and night can cause moisture to migrate within bins.

Spring is moderate risk. Warming temperatures and spring rains create humidity. Feed that survived winter can become vulnerable as temperatures rise.

Step by Step Guide to Proper Pig Feed Storage

This section provides the practical steps for storing pig feed safely. Follow these steps consistently to minimize mold and mycotoxin risk.

Step 1: Start With Clean Storage

Clean storage is the foundation of feed preservation. Mold spores from old feed contaminate new feed. A bin that looks empty can still harbor mold in corners, on walls, and in cracks.

Clean bins completely between batches of feed. Remove all old feed, dust, and debris. Sweep the interior thoroughly. Use a shop vacuum to remove dust from corners and seams. For bins that have had mold problems, wash the interior with a mild bleach solution and allow it to dry completely before refilling.

Clean augers, conveyors, and other equipment. These systems trap feed in cracks and corners. Disassemble equipment when possible and clean all surfaces. Pay special attention to the transition points where feed moves from one piece of equipment to another.

Clean the area around bins. Remove weeds, trash, and old feed spills. These attract pests and harbor mold. Keep the area clean to reduce the source of mold spores that can enter bins.

Inspect bins for damage while they are empty. Repair rust, holes, and damaged seals. Replace worn gaskets. Make sure lids fit tightly and close properly.

Step 2: Control Moisture at Every Point

Moisture control is the single most important factor in feed storage. Molds need water, and if you deny them water, they cannot grow.

For raw grain, dry to the correct moisture content before storage. Corn should be dried to 13 to 14 percent moisture for storage up to six months. For storage longer than six months, dry to 12 to 13 percent. Small grains like wheat and barley should be dried to 12 to 13 percent. Soybeans should be dried to 11 to 12 percent.

Dry grain immediately after harvest. Do not let wet grain sit in wagons or trucks while you wait for dryer space. Every hour of delay is an opportunity for mold growth.

For finished feed, control moisture from the start. Buy feed from reputable mills that control moisture in their production process. If you mix feed on farm, monitor the moisture content of ingredients. Do not add water or liquid ingredients unless you have a specific reason and a plan to manage the moisture increase.

Check the moisture content of feed regularly. Use a moisture meter designed for feed and grain. Calibrate the meter according to the manufacturer instructions. Test at several points in the bin, not just at the top.

Keep finished feed dry during storage. Make sure bins are sealed against rain and snow. Check for leaks after every storm. Keep feed covered during transport and while waiting to be used.

Step 3: Manage Temperature

Temperature affects both mold growth and moisture movement. Proper temperature management keeps feed cool and prevents condensation.

Cool grain after drying. Do not put warm grain into storage. Allow grain to cool to within 10 to 15 degrees Fahrenheit of the outside air temperature before storing.

Use aeration to control grain temperature. Run aeration fans to cool grain in the fall and warm it slightly in the spring to prevent condensation. The goal is to keep grain temperature close to the average outside temperature.

For finished feed, keep storage areas cool. Bins in direct sunlight heat up significantly. If possible, position bins in shaded areas or paint them white to reflect heat. Insulate bins that are exposed to extreme temperatures.

Monitor feed temperature regularly. Insert a temperature probe into stored feed and check several locations. A rise in temperature indicates mold activity. Mold generates heat as it grows, so a warm spot in a bin is a warning sign.

Step 4: Use First In, First Out Rotation

Feed should be used in the order it was received. This is called first in, first out rotation. It ensures that no feed sits in storage longer than necessary.

Label every delivery with the date received. Use a permanent marker on bags or a tag on bins. When you add new feed to a bin that contains old feed, record the date of the older feed and use it first.

Empty bins completely before adding new feed. Do not add new feed on top of old feed. The old feed at the bottom of the bin is at highest risk of mold and should be used first.

Plan feed orders to match usage. Order feed based on your expected consumption. Do not order extra feed just to have a surplus. Surplus feed is mold risk waiting to happen.

In feeders, empty and clean feeders regularly. Do not add fresh feed on top of old feed. Pigs that are fed in a clean feeder with fresh feed every time have lower exposure to mold.

Step 5: Protect Against Pests

Birds, rodents, and insects damage feed and introduce moisture and mold. Pest control is an essential part of feed storage.

Keep birds away from feed storage areas. Birds can enter bins through damaged lids and openings. They contaminate feed with droppings and carry mold spores. Use bird netting or other deterrents around feed storage areas. Keep bins sealed so birds cannot enter.

Control rodents around feed storage. Rats and mice chew through bags and feed on stored grain. They urinate and defecate in feed, introducing moisture and bacteria. Maintain a rodent control program with bait stations and traps. Keep the area around bins clean and free of vegetation that shelters rodents.

Control insects in stored grain. Insects damage grain and create conditions for mold growth. They also carry mold spores from kernel to kernel. Keep storage areas clean to reduce insect habitat. Consider using approved grain protectants if insect pressure is high.

Step 6: Monitor Feed Condition

Regular monitoring catches problems early, when they are easier to manage. Develop a monitoring schedule and stick to it.

Check bins daily. Look at the outside of bins for damage, leaks, and signs of pests. Listen for unusual sounds from aeration equipment. Check the area around bins for spilled feed that attracts pests.

Check feed visually at every transfer point. When feed moves from bin to wagon, from wagon to feeder, look at it. Fresh feed should have a consistent color and texture. Moldy feed may appear dusty, clumped, or discolored. Look for webbing, which indicates insect activity. Look for caked or crusted feed, which indicates moisture problems.

Smell feed at every transfer. Fresh feed has a slightly sweet, grain-like smell. Moldy feed smells musty, sour, or like rotting grain. A change in smell is often the first sign of a problem. Trust your nose. If feed smells wrong, do not feed it to pigs.

Check feeders regularly. Feed that sits in feeders for more than a day or two is at risk. Pigs that root and play in feed add moisture. Remove stale feed from feeders and replace with fresh feed.

Step 7: Manage Feed Spoilage When It Occurs

Despite your best efforts, feed will sometimes spoil. Have a plan for handling spoiled feed.

Isolate spoiled feed immediately. Remove it from the bin or feeder and set it aside. Do not mix it with good feed. Do not feed it to pigs.

Determine the extent of the problem. If only the top layer of feed in a bin is spoiled, you may be able to remove that layer and use the rest. If the spoilage is deeper, the entire bin may be contaminated.

Test spoiled feed for mycotoxins before making any decisions about using it. Do not assume that visible mold means mycotoxins are present, and do not assume that no visible mold means mycotoxins are absent. Testing is the only way to know.

Discard feed that is heavily molded or that tests positive for dangerous levels of mycotoxins. Do not feed it to pigs, and do not blend it with good feed to dilute it. Mycotoxins are not diluted by mixing. Blending contaminated feed with good feed just spreads the toxin through more feed.

Consider options for disposing of spoiled feed. In some cases, spoiled feed can be composted or spread on fields as fertilizer. Check local regulations before disposing of feed. Some mycotoxins persist in the environment and can cause problems for other animals or crops.

Common Mistakes in Pig Feed Storage

Many farms make the same mistakes when it comes to feed storage. Recognizing these mistakes helps you avoid them.

Mistake 1: Storing Feed Too Long

The most common mistake is keeping feed longer than necessary. Feed that sits in a bin for months is almost certain to develop mold problems. The longer feed is stored, the higher the risk.

Solution: Use a first in, first out rotation system. Order feed based on actual consumption. Keep only two to four weeks of finished feed on hand. For raw grain, use proper drying and aeration to extend safe storage life.

Mistake 2: Ignoring Moisture Content

Many farmers assume that feed is dry enough because it looks dry. Moisture content is invisible. Feed can look fine and still have too much moisture for safe storage.

Solution: Measure moisture content regularly with a calibrated moisture meter. Test grain at harvest and before storage. Test finished feed when it arrives and periodically during storage.

Mistake 3: Adding New Feed on Top of Old Feed

This is a common mistake that creates a hidden mold problem. Old feed at the bottom of a bin is compressed, may have higher moisture, and is at high risk of mold. Adding new feed on top makes the problem worse by pushing old feed deeper and making it harder to access.

Solution: Empty bins completely before adding new feed. If you must add new feed before the bin is empty, use the old feed first and clean the bin before adding new feed.

Mistake 4: Not Cleaning Bins Between Batches

A bin that is not cleaned between batches becomes a reservoir of mold. Old feed in corners and seams contaminates new feed. This is especially a problem in bins that are never completely emptied.

Solution: Clean bins completely between batches. Sweep and vacuum all surfaces. Wash bins that have had mold problems. Inspect and repair bins while they are empty.

Mistake 5: Ignoring Temperature Changes

Temperature changes cause moisture migration in stored grain. When the outside temperature drops, the grain near the bin wall cools. Moisture moves from warm grain to cool grain, creating condensation. This condensation creates wet spots where mold can grow.

Solution: Use aeration to manage grain temperature. Keep grain temperature close to the average outside temperature. Monitor grain temperature regularly and run aeration fans when needed to equalize temperature.

Mistake 6: Relying on Mold Inhibitors Instead of Good Management

Mold inhibitors, such as organic acids, can help preserve feed. However, they are not a substitute for good storage management. They cannot fix feed that is too wet or stored too long. They only slow mold growth, they do not stop it.

Solution: Use mold inhibitors as a supplement to good management, not as a replacement. Keep feed dry, cool, and clean. Use mold inhibitors only when feed conditions require extra protection, such as during hot, humid weather.

Mistake 7: Blending Moldy Feed With Good Feed

This is a dangerous mistake that comes from a misunderstanding of how mycotoxins work. Blending moldy feed with good feed does not eliminate mycotoxins. It just spreads them through more feed. Pigs that eat the blended feed still consume toxins, just at lower levels per pound of feed. Over time, even low levels of mycotoxins cause problems.

Solution: Never blend moldy feed with good feed. Test moldy feed for mycotoxins. Discard feed that is contaminated. The cost of discarding feed is less than the cost of health problems in your herd.

Mistake 8: Ignoring Feeders

Feeders are often overlooked in feed storage planning. Feed that sits in feeders for days is at high risk of mold. Pigs add moisture through saliva and rooting. Warm barn temperatures accelerate mold growth.

Solution: Adjust feeder settings to minimize waste and stale feed. Empty and clean feeders regularly. Feed smaller amounts more frequently to keep feed fresh.

Mistake 9: Not Keeping Records

Many farms do not track feed deliveries, storage times, or problems. Without records, you cannot identify patterns or make informed decisions about feed storage.

Solution: Keep a feed log that records delivery dates, batch numbers, moisture content, and any problems observed. Review the log regularly to identify trends and adjust your management.

Mistake 10: Not Testing Feed

Many farmers never test their feed for mycotoxins. They rely on visual inspection, which cannot detect mycotoxins. Mold can be present without visible signs, and mycotoxins can be present without mold.

Solution: Test feed regularly for mycotoxins, especially during high risk times. Test any feed that shows signs of spoilage. Test feed from new suppliers before using it. Testing is inexpensive compared to the cost of a mycotoxin outbreak.

Decision Thresholds for Feed Use

Knowing when to use feed and when to discard it is one of the most important decisions you will make. The following thresholds provide practical guidance.

Moisture Thresholds

For raw grain going into storage, use these moisture targets:

Corn for storage up to 6 months: 13 to 14 percent
Corn for storage longer than 6 months: 12 to 13 percent
Small grains (wheat, barley): 12 to 13 percent
Soybeans: 11 to 12 percent

For finished feed, the target is 12 percent moisture or less. Feed with moisture above 12 percent is at increased risk of mold and should be used within one to two weeks.

Temperature Thresholds

Monitor feed temperature and watch for these warning signs:

A temperature rise of 5 to 10 degrees Fahrenheit above ambient temperature indicates mold activity.
A temperature rise of more than 10 degrees Fahrenheit above ambient temperature indicates serious mold growth.
Temperature differences of more than 20 degrees Fahrenheit between the center and edges of a bin indicate moisture migration problems.

Visual Inspection Thresholds

Use these guidelines when inspecting feed:

No visible mold, no off smell: Feed is safe to use.
Slight musty smell, no visible mold: Feed is at risk. Test for mycotoxins before feeding to breeding stock.
Visible mold spots, musty or sour smell: Feed is contaminated. Test for mycotoxins. Do not feed to breeding stock or young pigs.
Heavy mold, caked feed, strong off smell: Feed is spoiled. Do not feed to any pigs. Discard the feed.

Mycotoxin Testing Thresholds

The following action levels are based on general guidance for pig feed. Note that these are not regulatory standards but practical guidelines. Check with your veterinarian or extension agent for specific recommendations for your situation.

Aflatoxin: Action level of 20 parts per billion for finishing pigs. Lower levels for breeding stock. Do not feed contaminated feed to breeding stock.
Deoxynivalenol (DON): Action level of 1 part per million for finishing pigs. Lower levels for breeding stock and young pigs. Feed refusal is common above 1 part per million.
Zearalenone: Action level of 1 part per million for breeding stock. Lower levels for young gilts. Do not feed contaminated feed to breeding stock.
Fumonisins: Action level of 10 parts per million for finishing pigs. Lower levels for breeding stock and young pigs.
Ochratoxin: Action level of 0.2 parts per million. Do not feed contaminated feed to any pigs.
T-2 toxin: Action level of 1 part per million. Do not feed contaminated feed to any pigs.

When test results are near these thresholds, consult your veterinarian or extension agent for specific advice. When test results are above these thresholds, discard the feed.

Decision Making for Breeding Stock

Breeding stock is the most sensitive group on the farm. Sows, gilts, and boars are more affected by mycotoxins than growing pigs. Zearalenone is especially damaging to reproduction.

For breeding stock, use more conservative thresholds:

Do not feed any feed that shows visible mold.
Do not feed any feed that has a musty or sour smell.
Test feed for mycotoxins before feeding to breeding stock, especially during breeding season.
When in doubt, discard the feed and buy new feed.

The cost of replacing a sow or losing a litter is far greater than the cost of discarding a bin of feed.

Monitoring and Recordkeeping

A good monitoring program catches problems early and helps you make better decisions. It also provides a record of your feed management practices, which can be valuable during disease investigations or audits.

Daily Monitoring

Perform these checks every day:

Inspect the exterior of all feed bins for damage, leaks, and signs of pests.
Check the area around bins for spilled feed and pest activity.
Observe feed as it moves through augers and into feeders.
Check feeders for stale or moldy feed.
Check pigs for signs of reduced feed intake or feed refusal.

Weekly Monitoring

Perform these checks every week:

Measure moisture content of feed in bins.
Check feed temperature in bins.
Inspect bin interiors through access openings.
Check aeration equipment for proper function.
Review feed usage and adjust orders based on consumption.

Monthly Monitoring

Perform these checks every month:

Empty and clean bins that are due for rotation.
Inspect bin interiors thoroughly for mold, corrosion, and damage.
Clean augers and conveying equipment.
Check and replace worn gaskets and seals.
Test feed for mycotoxins if you have not tested recently.

Seasonal Monitoring

Perform these checks at each season change:

Prepare for temperature changes by adjusting aeration schedules.
Check bins for damage from winter weather or summer heat.
Test stored grain for moisture and mold before warm weather arrives.
Review your feed storage plan and make adjustments based on the coming season.

Recordkeeping

Keep a feed log with the following information:

Delivery date and supplier for each batch of feed.
Batch number and feed type.
Moisture content at delivery.
Bin location where feed was stored.
Date feed was used or discarded.
Any problems observed, such as mold, off smells, or pest damage.
Results of any mycotoxin tests.
Actions taken in response to problems.

Keep the feed log in a location where all farm staff can access it. Review the log regularly to identify patterns and improve your management.

Using Records to Improve Management

Records are only useful if you use them. Review your feed log regularly and ask these questions:

Are there times of year when feed problems are more common?
Are certain suppliers or feed types associated with more problems?
Are certain bins or storage areas associated with more problems?
Is your rotation system working, or is feed sitting too long?
Are your monitoring checks catching problems early?

Use the answers to these questions to adjust your feed storage practices.

When to Call a Veterinarian or Extension Agent

Most feed storage problems can be managed with good practices. However, some situations require professional help. Contact your veterinarian or extension agent in the following situations.

Signs of Mycotoxin Exposure in Pigs

Call your veterinarian immediately if you see any of these signs:

Sudden drop in feed intake across multiple pigs or pens.
Vomiting, especially if it affects multiple pigs.
Swelling of the vulva in gilts or sows.
Enlarged uterus or other reproductive problems in breeding stock.
Reduced farrowing rates or increased abortions.
Poor growth or reduced weight gain across the herd.
Increased disease incidence or poor response to treatment.
Deaths, especially if they are sudden and unexplained.

These signs can indicate mycotoxin exposure, but they can also indicate other diseases. Your veterinarian can help you determine the cause and take appropriate action.

When to Test Feed

Contact your extension agent for guidance on mycotoxin testing in these situations:

You suspect feed spoilage but are not sure if it is safe to feed.
You are considering using feed that has been stored for a long time.
You have had a mycotoxin problem in the past and want to monitor.
You are changing feed suppliers and want to verify feed quality.
You are experiencing unexplained health or production problems in your herd.

Your extension agent can help you collect samples properly and interpret test results.

When to Seek Technical Assistance

Contact your extension agent for technical assistance in these situations:

You are designing or modifying feed storage facilities.
You are having persistent moisture problems in stored grain.
You are unsure how to manage aeration for your climate.
You want to develop a feed quality assurance program.
You are considering new feed storage technology.

Extension agents have training and resources to help you improve your feed storage systems.

When to Report to Authorities

In rare cases, mycotoxin problems may need to be reported to authorities. Contact your veterinarian or state animal health officials if:

You suspect that contaminated feed has caused a widespread disease outbreak.
You are discarding large quantities of feed and need guidance on disposal.
You suspect that contaminated feed was sold to other farms.

Your veterinarian can help you determine whether reporting is necessary.

Frequently Asked Questions

How long can pig feed be stored safely?

Finished pig feed should be used within two to four weeks of delivery. In hot, humid weather, use feed within two weeks. In cool, dry weather, feed can be stored up to four weeks. Raw grain can be stored for several months if it is dried to the correct moisture content and managed with aeration. The key is to monitor moisture, temperature, and condition regularly and to use a first in, first out rotation system.

Can I feed moldy feed to pigs if I mix it with good feed?

No. Mixing moldy feed with good feed does not eliminate mycotoxins. It only spreads the toxins through more feed. Pigs that eat the blended feed still consume mycotoxins, and over time, even low levels cause health problems. Do not blend moldy feed with good feed. Test moldy feed for mycotoxins and discard feed that is contaminated.

What are the signs that pigs have eaten moldy feed?

Pigs that eat moldy feed may show reduced feed intake, poor growth, vomiting, and diarrhea. Breeding stock may show reproductive problems such as swollen vulvas in gilts, reduced farrowing rates, and abortions. Some mycotoxins suppress the immune system, making pigs more susceptible to other diseases. If you see these signs, contact your veterinarian and test your feed for mycotoxins.

How do I test feed for mycotoxins?

Contact your extension agent or a commercial feed testing laboratory for guidance on sampling and testing. Collect samples from several locations in the bin and combine them into a composite sample. Follow the laboratory instructions for sample size and packaging. Tests are available for individual mycotoxins or for panels of multiple mycotoxins. Testing is inexpensive compared to the cost of a mycotoxin outbreak.

What is the best way to clean a feed bin?

Empty the bin completely and remove all old feed, dust, and debris. Sweep the interior thoroughly and use a shop vacuum to remove dust from corners and seams. For bins that have had mold problems, wash the interior with a mild bleach solution and allow it to dry completely before refilling. Inspect and repair any damage while the bin is empty.

Do mold inhibitors work?

Mold inhibitors, such as organic acids, can slow mold growth in feed. However, they are not a substitute for good storage management. They cannot fix feed that is too wet or stored too long. They only slow mold growth, they do not stop it. Use mold inhibitors as a supplement to good management, not as a replacement.

What moisture content should pig feed have?

Finished mash feed should have a moisture content of 12 percent or less. Feed with moisture above 12 percent is at increased risk of mold and should be used within one to two weeks. Raw grain should be dried to 13 to 14 percent moisture for storage up to six months and 12 to 13 percent for longer storage.

Can mycotoxins be destroyed by cooking or processing?

No. Mycotoxins are stable compounds that survive heat, freezing, and many processing steps. Cooking moldy feed does not make it safe. Grinding, pelleting, and extruding do not destroy mycotoxins. The only way to protect pigs from mycotoxins is to prevent mold growth in the first place and to discard feed that is contaminated.

Related Farming Guides

This section will be populated with links to related farming guides on pig production, feed management, and herd health topics.

Related Clinical & Scientific Guides

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.