Pig Feed Particle Size and Grinding Management

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

Key Takeaways

Optimal particle size for growing and finishing pigs ranges from 650 to 750 microns, with sows tolerating a slightly coarser grind (700-800 microns). Reducing particle size from 1000 to 700 microns can improve feed efficiency by 5-7% due to increased surface area for enzymatic digestion, particularly of starch locked within corn's protein matrix.
Grinding feed finer than 400 microns significantly elevates the risk of gastric ulcers by reducing stomach acid buffering time, potentially leading to reduced growth, carcass condemnations, and sudden death. Conversely, particle sizes exceeding 1000 microns lead to reduced nutrient digestion and undigested feed passage.
Particle size uniformity is as critical as the average size; a consistent grind improves nutrient digestion and minimizes feed sorting by pigs, ensuring a balanced intake of all dietary components. Inconsistent grinds, with a wide distribution of fine and coarse particles, mimic feeding a mixed diet of fine and coarse feeds.
Regular monitoring of particle size using sieve shakers (at least monthly) and after mill adjustments is essential, as screen wear, hammer dulling, and roll gap changes can alter grind consistency. Unexpected drops in feed intake or average daily gain should prompt immediate particle size evaluation.
Different pig age groups benefit from specific particle sizes: nursery pigs (650-700 microns) require finer grinds for immature digestive systems, while gestating sows (700-800 microns) can utilize coarser grinds to slow passage and promote satiety. Lactating sows benefit from a finer grind (650-750 microns) for maximal nutrient uptake.

Getting feed grinding right is one of the simplest and most cost effective ways to improve pig performance and reduce feed waste on any swine operation. This guide covers the science and practice of managing pig feed particle size, from understanding why grind size matters, to calibrating your mill, to troubleshooting common problems. It is written for independent producers, farm managers, and feed mill operators who want practical, actionable guidance they can apply immediately.

At a Glance

Target particle size for pigs: 650 to 750 microns for growing and finishing pigs. Sows can handle a slightly coarser grind around 700 to 800 microns.
Feed efficiency improvement: Reducing particle size from 1000 to 700 microns can improve feed efficiency by roughly 5 to 7 percent.
Too fine causes problems: Grinding below 400 microns increases the risk of stomach ulcers and creates dusty, unpalatable feed.
Too coarse wastes money: Particle sizes above 1000 microns reduce nutrient digestion and pass through pigs undigested.
Uniformity matters as much as average size: A consistent particle size distribution improves digestion and reduces feed sorting.
Check your grind regularly: Use a sieve shaker or a simple hand sieve set at least once a month and after any mill change.
Match grinding to pig age: Nursery pigs need a finer grind than sows, but all pigs benefit from staying within the target range.
Monitor feed intake and average daily gain: If either drops unexpectedly, check particle size before assuming a health problem.

Why Particle Size Matters in Pig Feed

Pig feed particle size is the single most important physical characteristic of a complete feed, yet it is often overlooked. The size of the particles in your feed affects how well pigs digest the nutrients, how much feed they waste, and even their stomach health. Understanding the relationship between grind size and pig performance helps you make informed decisions at the mill.

The Digestibility Connection

Pigs do not have the ability to chew their feed thoroughly. They take a mouthful, grind it briefly, and swallow. The digestive system then has to work on whatever particle size the feed mill produced. Smaller particles expose more surface area to digestive enzymes, which means more complete digestion of starch, protein, and energy.

Corn is the primary energy source in most pig diets, and its starch is locked inside a hard protein matrix. Grinding breaks that matrix open and exposes the starch to enzymes in the small intestine. When corn is ground too coarsely, much of the starch remains trapped and passes through the pig undigested. This is wasted money and wasted nutrition.

Research consistently shows that reducing particle size from roughly 1000 microns to 700 microns improves dry matter and energy digestibility. The improvement is not linear across all sizes. The biggest gains come when you move from a coarse grind to a medium grind. The additional gains from going from medium to fine are smaller and come with increased risks.

Feed Efficiency and Growth Performance

The most direct economic benefit of proper particle size is improved feed efficiency. Pigs fed a correctly ground diet convert feed to body weight more efficiently than pigs fed a coarse diet. This means you need less feed to produce the same amount of pork, which directly improves your bottom line.

For growing and finishing pigs, the relationship between particle size and feed efficiency is well established. Moving from a coarse grind around 1000 microns to a target grind around 700 microns typically improves feed efficiency by 5 to 7 percent. On a farm feeding 1000 tons of feed per year, that improvement can translate into substantial feed cost savings.

Average daily gain also responds to particle size, though the effect is smaller than the effect on feed efficiency. Pigs on a properly ground diet tend to gain slightly faster, likely because they digest more of what they eat. However, if particle size gets too fine, gain can suffer because the feed becomes dusty and less palatable.

Stomach Health and Ulcer Risk

There is a well documented link between very fine particle sizes and stomach ulcers in pigs. When feed is ground too finely, below about 400 microns, the feed moves through the stomach more quickly. This reduces the time the stomach has to buffer the acid produced during digestion. The lower portion of the stomach, which is not protected by the same glandular lining as the rest of the organ, becomes exposed to acid and can develop ulcers.

Stomach ulcers are a serious welfare and economic issue. They can cause sudden death in severe cases, reduced growth in chronic cases, and they are a common finding at slaughter. The risk increases dramatically when particle size drops below 400 microns, but some pigs can develop ulcers at slightly larger sizes if other stress factors are present.

The opposite problem, feed that is too coarse, also creates issues. Coarse feed is more likely to be sorted by pigs. They will eat the finer particles and leave the coarse ones, which means they do not receive a balanced diet. This sorting behavior is especially problematic in group housing where dominant pigs can select the best particles and leave the less desirable ones for subordinate animals.

Feed Handling and Mill Throughput

Particle size also affects how feed flows through your mill, your bins, and your feeders. Very fine feed can bridge in bins and create blockages. It also creates more dust, which is a nuisance and a safety hazard in the mill. Coarse feed flows well but may separate during transport, with fine particles settling to the bottom of the bin and coarse particles staying on top.

The right particle size range balances all of these factors. It is fine enough for good digestion and feed efficiency, but not so fine that it creates ulcer risk or handling problems. The target range of 650 to 750 microns for growing and finishing pigs achieves this balance in most commercial settings.

Understanding Particle Size Measurement

Before you can manage particle size, you need to understand how it is measured. Particle size is reported in microns, which are one millionth of a meter. For reference, a typical grain of table salt is about 100 microns, and a human hair is about 70 microns. Ground feed particles range from very fine dust under 100 microns to coarse pieces over 2000 microns.

Mean Particle Size

The mean particle size is the average size of all the particles in a sample. This is the number most people refer to when they talk about grind size. A target of 700 microns means the average particle in the feed is 700 microns across.

Mean particle size is calculated by passing a feed sample through a stack of sieves with progressively smaller openings. The weight of material retained on each sieve is recorded, and a mathematical calculation produces the geometric mean diameter. This is the standard measure used in the feed industry.

Particle Size Uniformity

The uniformity of the grind is just as important as the average size. A feed with a mean particle size of 700 microns could have all particles between 500 and 900 microns, which would be a very uniform grind. Or it could have a mix of very fine dust and very coarse pieces, which would still average 700 microns but would be much less uniform.

Uniformity is measured by the geometric standard deviation. A lower standard deviation means a more uniform grind. Pigs perform better on a uniform grind because they digest all particles at a similar rate. A nonuniform grind acts like a mix of fine and coarse feed, with the fine portion digesting quickly and the coarse portion passing through partially undigested.

How to Test Particle Size on Your Farm

You do not need an expensive laboratory to check your particle size. A simple sieve shaker with a set of US standard sieves is affordable and easy to use. Many feed supply companies sell complete sieve sets with instructions for farm use.

To test your feed, take a representative sample from your mill or feeder. A sample of about 100 grams is sufficient. Place the sample on the top sieve of a stacked set and shake for about 10 minutes. Weigh the material retained on each sieve and record the results. You can then calculate the mean particle size using a spreadsheet or an online calculator.

If you do not have a sieve shaker, you can do a rough check with a handful of feed. Rub the feed between your fingers. A properly ground feed should feel like coarse sand or fine cornmeal. If it feels like flour, it is too fine. If you can see large chunks of corn, it is too coarse. This hand test is not precise, but it can help you spot major problems between formal tests.

How Grinding Equipment Affects Particle Size

The type of mill you use has a major effect on the particle size you produce. Each mill type has its own characteristics, advantages, and limitations. Understanding these helps you choose the right equipment for your operation and get the best performance from what you already have.

Hammer Mills

Hammer mills are the most common type of mill on pig farms. They work by swinging hammers that strike the grain and force it through a screen. The screen opening size is the primary control on particle size, but hammer speed, hammer condition, and the number of hammers also play a role.

Hammer mills are versatile and can produce a wide range of particle sizes by changing the screen. They are also relatively inexpensive to purchase and maintain. The main disadvantage is that they produce a less uniform grind than roller mills, with a wider range of particle sizes.

To get the best performance from a hammer mill, keep the hammers in good condition. Worn hammers produce a coarser and less uniform grind. Replace hammers when the edges become rounded or chipped. Also check the screen regularly for wear or damage. A worn screen has larger openings than intended and will produce a coarser feed.

The speed of the hammer mill also affects particle size. Higher tip speeds produce finer particles. If your mill has adjustable speed, experiment to find the setting that gives you the target particle size with the best throughput.

Roller Mills

Roller mills crush grain between two rotating cylinders. They produce a more uniform particle size than hammer mills, with fewer fine particles and fewer coarse particles. This uniformity is beneficial for pig digestion and feed handling.

Roller mills are more energy efficient than hammer mills and produce less dust. However, they are more expensive to purchase and require more maintenance. The rolls need to be adjusted as they wear, and the gap between rolls must be set correctly for the target particle size.

The main advantage of roller mills for pig feed is the improved uniformity. A roller mill can produce a grind where most particles are within a narrow range around the target size. This uniformity improves digestion and reduces feed sorting.

Grinding Capacity and Throughput

Your mill needs to have enough capacity to meet your feed demand. If the mill is undersized, you may be tempted to increase the screen size or roll gap to get more throughput. This produces a coarser feed and undermines your particle size goals.

When planning grinding capacity, consider your peak demand, not just your average demand. If you grind feed once a week, you need enough capacity to produce a weeks worth of feed in one grinding session. If you grind daily, you need less capacity but more consistency in your grinding schedule.

Screen Size Selection

For hammer mills, screen size is the main control on particle size. A general rule is that the mean particle size will be about 1.5 to 2 times the screen opening size. So a 3/16 inch screen, which is about 4760 microns, will produce a grind around 700 to 950 microns. You will need to test your specific mill to find the exact relationship.

Start with the manufacturers recommendation for your target particle size, then adjust based on your own sieve tests. Keep records of which screens produce which particle sizes so you can make quick changes when needed.

Step by Step Guide to Grinding Feed for Pigs

Setting up a proper grinding program involves several steps, from calibrating your mill to testing the finished feed. Follow this process to get your particle size in the target range and keep it there.

Step 1: Determine Your Particle Size Target

Decide what particle size you want to produce based on the pigs you are feeding. Use these guidelines as a starting point:

Nursery pigs, 650 to 700 microns
Growing and finishing pigs, 650 to 750 microns
Gestating sows, 700 to 800 microns
Lactating sows, 650 to 750 microns

These ranges balance digestion, feed efficiency, and stomach health. If you are currently feeding a coarser grind, do not make a sudden change. Step down gradually over a week or two to give the pigs time to adjust.

Step 2: Calibrate Your Mill

Run a test batch of feed through your mill using your current screen or roll setting. Take a sample and test the particle size. Compare the result to your target.

If the particle size is too coarse, reduce the screen size or tighten the roll gap. If it is too fine, increase the screen size or widen the roll gap. Run another test batch and test again. Repeat until you achieve the target particle size.

Record the settings that produce your target particle size. This becomes your starting point for future grinding. Keep this information posted near the mill so everyone who operates the equipment knows the correct settings.

Step 3: Grind a Full Batch

Once the mill is calibrated, grind a full batch of feed. Take samples from different points in the batch to check for consistency. The particle size should be consistent from the beginning to the end of the batch.

If you are using a mix of grains, such as corn and soybean meal, the grinding process will produce different particle sizes for each ingredient. This is normal. The target particle size refers to the overall mix, not each individual ingredient.

Step 4: Test the Finished Feed

Take a sample of the finished feed and test the particle size. This confirms that the grinding process produced the expected result. It also gives you a baseline for future testing.

Store the feed in a clean, dry bin. Properly ground feed has a longer shelf life than coarse feed because the increased surface area allows for more even moisture distribution. However, very fine feed can absorb moisture more quickly, so keep bins sealed and dry.

Step 5: Monitor Pigs and Feed

Watch your pigs closely in the weeks after changing particle size. Look for changes in feed intake, growth rate, and behavior. Pigs on a properly ground diet should clean up their feed efficiently without excessive sorting.

Check feeders regularly to ensure feed is flowing properly. Fine feed can bridge in feeders, preventing pigs from accessing feed. Coarse feed can pile up in corners and go uneaten. Adjust feeder settings as needed to maintain good feed flow.

Step 6: Retest Regularly

Particle size does not stay consistent on its own. Screens wear, hammers dull, rolls lose their adjustment, and grain moisture changes. Retest your particle size at least once a month and after any maintenance or adjustment to the mill.

Keep a log of your test results. This helps you spot trends and identify when the mill is drifting out of adjustment. It also provides documentation if you need to troubleshoot a performance problem.

Adjusting Particle Size for Different Pig Groups

While the target range of 650 to 750 microns works for most pigs, there are some important differences between pig groups that you should consider.

Nursery Pigs

Nursery pigs have immature digestive systems and benefit from a finer grind. The target of 650 to 700 microns helps them digest their feed more completely and reduces the amount of undigested feed reaching the large intestine, where it can cause digestive upset.

However, nursery pigs are also the most sensitive to the negative effects of very fine feed. Dusty feed reduces intake and can cause respiratory irritation. If you are feeding a fine grind, make sure your feeders are adjusted properly to minimize dust and waste.

Some nursery diets include ingredients that are processed differently, such as cooked cereals or milk products. These ingredients are already highly digestible and do not need the same degree of grinding as raw grain.

Growing and Finishing Pigs

Growing and finishing pigs are the largest group on most farms and consume the most feed. The target of 650 to 750 microns applies to this group. This range gives the best combination of feed efficiency and stomach health.

As pigs grow, their digestive capacity increases. Some producers use a slightly coarser grind for finishing pigs to reduce mill wear and energy costs. If you do this, keep the particle size below 800 microns to avoid losing the digestibility benefits.

Sows

Sows have larger digestive systems and can handle a coarser grind. A target of 700 to 800 microns for gestating sows is appropriate. This coarser grind helps slow feed passage and keeps sows feeling full, which can reduce stereotypic behaviors associated with hunger.

Lactating sows need a finer grind, around 650 to 750 microns, to maximize nutrient intake during this high demand period. The increased digestibility helps sows maintain body condition while producing milk for their piglets.

Boars

Boars have lower nutrient requirements than growing pigs or lactating sows. A coarse grind around 800 microns is acceptable. The main consideration is maintaining body condition without overfeeding, and a coarser grind can help with this.

Common Mistakes in Pig Feed Grinding

Even experienced producers make mistakes with particle size. Here are the most common problems and how to avoid them.

Grinding Too Coarse to Save Money

Some producers use a coarse grind because it increases mill throughput and reduces energy costs. This is a false economy. The feed efficiency losses from coarse grinding far outweigh the small savings in milling costs.

A coarse grind above 1000 microns can reduce feed efficiency by 5 percent or more. On a farm feeding 1000 tons of feed per year at $300 per ton, that is a loss of $15,000 per year. The energy savings from coarse grinding are typically less than $1000 per year.

Grinding Too Fine to Maximize Digestibility

At the other extreme, some producers grind very fine to maximize digestibility. This also backfires. Below about 400 microns, the risk of stomach ulcers increases dramatically. Ulcers cause poor performance, sudden death, and carcass condemnations at slaughter.

Very fine feed also becomes dusty and unpalatable. Pigs eat less dusty feed, which reduces intake and growth. The increased digestibility of very fine feed does not compensate for the reduced intake.

Ignoring Particle Size Uniformity

Some producers check their average particle size but ignore uniformity. A feed with a wide particle size distribution acts like a mix of fine and coarse feed. The fine particles digest quickly, while the coarse particles pass through partially undigested.

Uniformity is especially important for pelleted feed. If you are pelleting, the grinding process before pelleting determines the particle size in the final pellet. A uniform grind produces a more consistent pellet with better durability.

Not Adjusting for Grain Moisture

Grain moisture affects grinding. Dry grain grinds finer than wet grain at the same mill setting. If you change grain sources or harvest new crop grain, retest your particle size and adjust the mill as needed.

High moisture grain also grinds less efficiently and can clog screens. If you are grinding high moisture grain, consider drying it first or using a mill designed for high moisture material.

Forgetting to Maintain the Mill

A poorly maintained mill produces inconsistent particle size. Worn hammers, damaged screens, and misaligned rolls all affect grind quality. Follow the manufacturers maintenance schedule and inspect the mill regularly.

Keep spare screens and hammers on hand so you can replace worn parts immediately. Do not wait until the mill fails completely to address maintenance issues.

Monitoring and Recordkeeping for Particle Size

Consistent particle size requires consistent monitoring. Set up a simple system to track your grinding performance and catch problems early.

What to Record

Keep a grinding log that includes the following information for each batch:

Date and time of grinding
Grain source and moisture content
Mill settings, including screen size or roll gap
Target particle size
Actual particle size from sieve test
Any notes on mill condition or adjustments

This log helps you identify patterns. If particle size drifts over time, you can see when the drift started and what changed. It also provides documentation if you need to troubleshoot a performance problem with your pigs.

How Often to Test

Test particle size at least once a month as a routine check. Test more frequently if you are making changes to your mill, changing grain sources, or experiencing pig performance problems.

Test every batch if you are just starting a particle size management program or if you have had problems with inconsistent grinding. Once you have established a consistent process, you can reduce testing to a monthly check.

Signs That Particle Size Has Changed

You can often spot particle size problems without a sieve test. Watch for these signs:

Feed intake drops suddenly
Pigs sort their feed, leaving coarse particles in the feeder
Dust levels increase in the barn
Feed bridges in bins or feeders
Stomach ulcers appear at slaughter
Feed efficiency worsens without other explanations

If you see any of these signs, test your particle size immediately. Even if the test shows acceptable particle size, investigate other causes of the problem.

Working With Your Feed Supplier

If you purchase feed from a commercial mill, ask about their particle size management program. A reputable mill should be able to provide particle size data for their feeds. Some mills offer this information on the feed tag or on request.

If you mix your own feed but purchase ground grain, ask your supplier for particle size data. Hold them accountable to the same standards you would apply to your own mill.

Troubleshooting Particle Size Problems

When particle size is outside the target range, work through a systematic process to find and fix the problem.

Problem: Particle Size Too Coarse

If your sieve test shows a mean particle size above 800 microns, check these items:

Screen size: Is the correct screen installed? Is it worn or damaged?
Hammer condition: Are the hammers worn or chipped?
Roll gap: Is the gap between rolls set correctly?
Grain moisture: Is the grain wetter than usual?
Mill speed: Is the mill running at the correct speed?

Fix the most likely cause and retest. If the problem persists, check the next item on the list.

Problem: Particle Size Too Fine

If your sieve test shows a mean particle size below 600 microns, check these items:

Screen size: Is the screen smaller than intended?
Roll gap: Are the rolls set too tight?
Grain moisture: Is the grain drier than usual?
Mill speed: Is the mill running faster than normal?

Again, fix the most likely cause and retest.

Problem: Inconsistent Particle Size

If your particle size varies from batch to batch, check these items:

Grain source: Are you using different grain sources with different moisture or hardness?
Mill maintenance: Are the hammers or rolls wearing unevenly?
Screen condition: Is the screen partially blocked or damaged?
Grinding time: Are you grinding for consistent durations?

Keep a log of your batches to identify which variable is causing the inconsistency.

Problem: Good Particle Size but Poor Pig Performance

If your particle size is in the target range but pigs are still performing poorly, consider other factors:

Feed formulation: Is the diet balanced for the pigs age and weight?
Feed intake: Are pigs eating enough?
Water availability: Do pigs have access to clean, fresh water?
Health status: Are there disease or parasite issues?
Environmental conditions: Is the barn too hot, too cold, or poorly ventilated?

Particle size is one piece of the puzzle. If your particle size is correct, look at the other factors that affect pig performance.

When to Call a Veterinarian or Extension Agent

Most particle size problems can be solved with adjustments to your mill and grinding process. However, there are times when you need professional help.

Call Your Veterinarian If

Pigs show signs of stomach ulcers, including pale skin, reduced appetite, or sudden death
Feed efficiency drops sharply without an obvious cause
Pigs vomit blood or pass dark, tarry feces
Multiple pigs show the same digestive or respiratory symptoms
You suspect a disease outbreak that is affecting feed intake or digestion

Stomach ulcers can be managed with dietary changes and medication, but they require a veterinary diagnosis. Do not try to treat ulcers on your own.

Call Your Extension Agent If

You need help interpreting your particle size test results
You want to compare your grinding program to industry benchmarks
You are considering new milling equipment and want advice
You need help calculating the economic impact of particle size changes
You want to set up a feed quality monitoring program

Extension agents have resources and expertise that can help you improve your grinding program. They can also connect you with other producers who have solved similar problems.

Work With a Nutritionist If

You are changing your feed formulation and need to adjust particle size recommendations
You are considering new feed ingredients with different grinding characteristics
You want to optimize your feeding program for specific production goals
You are experiencing performance problems that you cannot explain

A swine nutritionist can help you integrate particle size management into your overall feeding program.

Economic Considerations of Particle Size Management

Particle size management is one of the most cost effective improvements you can make to your swine operation. The benefits come from improved feed efficiency, which directly reduces your feed costs.

Calculating the Value of Particle Size

To calculate the value of improving your particle size, start with your annual feed usage and feed cost. If you feed 1000 tons per year at $300 per ton, your annual feed cost is $300,000.

A 5 percent improvement in feed efficiency saves 5 percent of your feed cost, or $15,000 per year. Even a 2 percent improvement saves $6000 per year. These savings quickly pay for the cost of a sieve set, mill maintenance, and the time spent testing.

Costs of Particle Size Management

The costs of particle size management include:

Sieve set and shaker, $200 to $500
Replacement screens and hammers, varies by mill
Time for testing and recordkeeping, 1 to 2 hours per month
Potential reduction in mill throughput with finer grinding

These costs are small compared to the potential savings from improved feed efficiency.

Return on Investment

Most producers see a positive return on investment within the first few months of a particle size management program. The key is consistency. One test does not solve the problem. You need an ongoing program of testing, adjusting, and monitoring.

If you are considering upgrading your milling equipment, factor in the particle size benefits. A roller mill that produces a more uniform grind may be worth the higher purchase price if it improves feed efficiency enough to pay for itself over time.

Advanced Particle Size Management

Once you have the basics of particle size management in place, you can consider more advanced strategies to further improve your operation.

Pelleting and Particle Size

If you pellet your feed, the grinding process before pelleting determines the particle size in the final pellet. The pelleting process itself further reduces particle size, so the final pellet may have a smaller particle size than the ground meal.

When pelleting, aim for a grind of 650 to 750 microns before pelleting. The pelleting process will reduce this to around 500 to 600 microns in the final pellet. This is acceptable for most pigs, but monitor for ulcer risk if you feed very fine pellets.

Ingredient-Specific Grinding

Different ingredients have different grinding characteristics. Corn grinds relatively easily, while soybean meal is softer and grinds finer at the same mill setting. If you are using a mix of ingredients, you may need to adjust your mill to achieve the target particle size for the overall mix.

Some producers grind ingredients separately and mix them after grinding. This allows you to optimize the particle size for each ingredient. However, it requires additional equipment and handling, so weigh the benefits against the costs.

Moisture Management

Grain moisture affects grinding efficiency and particle size. Dry grain grinds finer and more efficiently than wet grain. If you are using grain with variable moisture, consider drying to a consistent moisture level before grinding.

High moisture grain, above 15 percent, can clog screens and produce an inconsistent grind. If you feed high moisture corn, consider using a roller mill, which handles high moisture grain better than a hammer mill.

Grinding for Specific Feeding Systems

Your feeding system can affect the ideal particle size. If you use liquid feeding, the particle size in the liquid ration is less critical because the feed is soaked and the particles soften. However, you still need to grind fine enough for good digestion.

If you use a restricted feeding program, where pigs are fed a set amount each day, a coarser grind may be acceptable because the pigs are not eating to appetite. If you feed ad libitum, a finer grind within the target range is better because it improves feed efficiency.

Environmental and Safety Considerations

Grinding feed creates dust and noise. Managing these issues protects your workers and your pigs.

Dust Control

Very fine feed creates more dust than coarser feed. Dust is a respiratory hazard for workers and pigs, and it can be explosive in confined spaces. Keep dust levels down by:

Maintaining the target particle size range
Using dust collection systems in the mill
Keeping the mill area clean
Wearing appropriate respiratory protection when working in dusty areas

If you see visible dust in the air when grinding, investigate the cause. It may be a sign that your grind is too fine or that your dust collection system is not working properly.

Noise Protection

Hammer mills and roller mills are noisy. Prolonged exposure to mill noise can cause hearing damage. Require workers to wear hearing protection when operating or working near the mill.

Consider installing the mill in a separate room or enclosure to reduce noise exposure. Regular maintenance can also reduce noise levels by keeping the mill running smoothly.

Fire Safety

Fine feed dust is combustible and can explode if it reaches a high enough concentration in the air. Keep the mill area clean and free of dust accumulation. Install proper ventilation and consider explosion relief panels if you have a large milling operation.

Do not smoke or use open flames near the mill. Keep a fire extinguisher nearby and train workers on how to use it.

Integrating Particle Size Management into Your Operation

Particle size management is not a one time project. It is an ongoing part of your feed management program. To make it work, integrate it into your daily and monthly routines.

Daily Checks

Every day, take a quick look at your feed as it comes out of the mill. Rub a handful between your fingers to check the texture. Look for any obvious changes from the previous day. If something looks different, investigate before grinding more feed.

Check your feeders daily to ensure feed is flowing properly. Look for signs of sorting or feed buildup. Adjust feeder settings as needed.

Weekly Checks

Once a week, do a more thorough check of your mill. Inspect the hammers or rolls for wear. Check the screen for damage or blockage. Listen for any unusual noises that might indicate a problem.

Review your grinding log to identify any trends in particle size or mill performance. Address any issues before they become major problems.

Monthly Checks

Once a month, run a full sieve test on your feed. Compare the results to your target particle size. Adjust the mill as needed and record any changes.

Review your pig performance data, including feed intake, average daily gain, and feed efficiency. Look for any changes that might be related to particle size.

Quarterly Reviews

Every quarter, do a more comprehensive review of your particle size management program. Evaluate your target particle sizes and adjust them if needed. Consider whether your milling equipment is still appropriate for your operation.

Review your records and identify any recurring problems. Develop a plan to address them. Consider consulting with your extension agent or nutritionist for a fresh perspective.

Frequently Asked Questions

What is the ideal pig feed particle size?

The ideal particle size for growing and finishing pigs is 650 to 750 microns. Nursery pigs do well at 650 to 700 microns, and sows can handle 700 to 800 microns. This range balances feed efficiency, nutrient digestibility, and stomach health. Feed ground below 400 microns significantly increases the risk of stomach ulcers, while feed ground above 1000 microns reduces digestibility and wastes nutrients.

How do I test pig feed particle size on my farm?

You can test particle size with a set of standard sieves and a shaker. Take a 100 gram sample of feed, place it on the top sieve, and shake for about 10 minutes. Weigh the material retained on each sieve and calculate the geometric mean diameter using a spreadsheet or online calculator. Many feed supply companies sell complete sieve sets with instructions. As a rough check, properly ground feed should feel like coarse sand between your fingers.

What happens if pig feed is ground too fine?

Feed ground too fine, below about 400 microns, increases the risk of stomach ulcers in pigs. The fine particles move through the stomach quickly, reducing the buffering time and exposing the lower stomach to acid. Very fine feed also becomes dusty and unpalatable, which reduces feed intake and growth. It can also bridge in bins and feeders, causing feed flow problems.

What happens if pig feed is ground too coarse?

Coarse feed above 1000 microns reduces nutrient digestibility because the digestive enzymes cannot penetrate the large particles. This wastes feed and reduces feed efficiency. Coarse feed is also more likely to be sorted by pigs, with them eating the fine particles and leaving the coarse ones. This leads to an unbalanced diet and wasted feed.

Does pellet size matter for pigs?

Pellet size matters for feed intake and pig preference, but it is separate from particle size. The particle size of the ground grain before pelleting determines the digestibility of the final pellet. When pelleting, aim for a grind of 650 to 750 microns before pelleting. The pelleting process will further reduce the effective particle size in the final pellet.

How often should I check my feed particle size?

Check particle size at least once a month as a routine part of your feed management program. Test more frequently if you change grain sources, adjust your mill, or notice pig performance problems. Some producers test every batch when they are first establishing their particle size program, then reduce to monthly testing once they have consistent results.

Can I use the same grind for all pigs on my farm?

You can use the same grind for most pigs, but you may need to adjust for different groups. Nursery pigs benefit from a finer grind around 650 to 700 microns. Growing and finishing pigs do well at 650 to 750 microns. Sows can handle a coarser grind of 700 to 800 microns. If you only have one mill, target 700 microns for the overall operation and adjust your feeding program as needed.

How does grain moisture affect particle size?

Grain moisture affects both the grinding process and the resulting particle size. Dry grain grinds finer than wet grain at the same mill setting. High moisture grain, above 15 percent, can clog screens and produce an inconsistent grind. If you change grain sources or harvest new crop grain, retest your particle size and adjust the mill as needed.

Related Farming Guides

This section will be populated with links to related farming guides on swine nutrition, 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.