Broiler Feed Particle Size: Effects on Intake and Digestion

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

Key Takeaways

• Optimal broiler mash feed particle size is characterized by a geometric mean diameter of 600 to 900 microns and a geometric standard deviation below 2.0, ensuring adequate gizzard stimulation for digestion and preventing feed sorting.
• High-quality pellets, defined by durability exceeding 80% and fines below 10%, are crucial for maximizing feed intake and weight gain by facilitating rapid consumption and minimizing waste.
• Fine feed particles (<600 microns) or excessive fines in pellets (>10%) lead to reduced feed intake, impaired gizzard function, accelerated digesta passage, and consequently, poorer nutrient digestion and feed conversion efficiency.
• Monitoring feed particle size via sieve analysis and pellet quality through fines percentage testing is essential, with thresholds like >20% fines or a feed intake drop of >5% necessitating immediate intervention with the feed mill or handling system.
• Feed form transitions, such as from mash to crumbles or pellets, require gradual implementation over several days to allow digestive adaptation and prevent performance dips, with crumbles being ideal for the starter phase (0-10 days).

Getting feed particle size right is one of the most cost-effective adjustments you can make in a broiler operation. The physical form of your feed, whether it comes as mash, crumble, or pellet, and the particle size within those forms, directly shapes how much your birds eat, how well they digest nutrients, and ultimately how efficiently they convert feed into body weight. This guide explains how particle size works in the broiler digestive tract, how to evaluate your current feed, and how to adjust your feeding program for better performance. It is written for broiler growers, farm managers, and feed mill operators who want practical, actionable information they can apply to their own flocks.

At a Glance

Understanding Broiler Feed Forms and Particle Size

Broilers can receive feed in several physical forms. The most common are mash, crumble, and pellet. Each form has a different particle size profile, and each affects bird behavior and digestion differently.

Mash feed is ground grain mixed with other ingredients. It is the simplest form and the cheapest to produce. The particle size of mash feed depends entirely on the grinding process. If the grain is ground too fine, the mash becomes dusty and birds eat less. If it is ground too coarse, birds may sort the feed and leave the smaller particles behind.

Crumble feed is made by pelleting the feed and then crumbling the pellets into smaller pieces. Crumbles are often used for young chicks because they are easier for small birds to pick up than whole pellets, but they still retain the benefits of pelleting.

Pellet feed is made by compressing ground feed through a die under heat and pressure. Pellets bind the ingredients together, which prevents sorting and reduces waste. Pellets also increase feed density, allowing birds to consume more feed in less time. The pelleting process involves heat, which can improve the digestibility of some nutrients, particularly starch.

The particle size of a pellet is less about the individual grain particles and more about the quality of the pellet itself. A good pellet holds together well and produces few fines, which are the small particles and dust that break off pellets during handling and feeding.

How Particle Size Affects Feed Intake

Feed intake is the starting point for broiler performance. A bird cannot grow if it does not eat. Particle size influences intake in several ways.

First, birds have a preference for larger particles. Research and practical observation both show that broilers will eat pellets over mash when given the choice. They will also eat crumbles over fine mash. This preference is not just a matter of taste. Larger particles are easier for birds to pick up and swallow. Fine, dusty feed sticks to the beak and is less appealing.

Second, fine particles can cause physical problems that reduce intake. When feed is too fine, it can accumulate in the crop and form a paste. This slows the passage of feed through the digestive tract and makes birds feel full for longer. In severe cases, impacted crops can develop, which requires veterinary attention.

Third, particle size affects how quickly birds can consume their daily feed allowance. Birds on pelleted feed spend less time eating because they can consume more feed per peck. This matters in hot weather when birds reduce their activity to stay cool. A bird that can eat quickly during cooler parts of the day will consume more total feed than a bird that must spend hours picking at fine mash.

The practical takeaway is that feed form and particle size directly control how much your birds eat. If you want maximum intake, you want a high quality pellet with few fines. If you feed mash, you want a coarse grind that birds can eat easily without sorting.

How Particle Size Affects Digestion

The digestive system of a broiler is designed to process feed of a certain physical character. The gizzard, which is the muscular stomach, plays a central role. When feed enters the gizzard, the strong muscles grind it against small stones or grit that the bird has consumed. This grinding action breaks feed into smaller pieces and mixes it with digestive juices.

The gizzard works best when it has something coarse to grind. Coarse particles stimulate the gizzard muscles to contract more strongly. This increased muscular activity leads to a larger, more developed gizzard. A well developed gizzard grinds feed more effectively, which improves nutrient release and digestion.

When feed is ground too fine, the gizzard has little work to do. The muscles weaken, the gizzard shrinks, and feed passes through the digestive tract more quickly. Faster passage means less time for enzymes to break down nutrients and less time for the intestine to absorb them. The result is poorer feed conversion and more undigested nutrients in the manure.

The effect is measurable. Birds fed coarse mash or high quality pellets typically show better nutrient digestibility than birds fed fine mash. This is partly because the gizzard functions better and partly because larger particles slow the passage rate of digesta through the gut, giving digestive enzymes more time to act.

Starch digestion is particularly affected. In whole grains and coarsely ground grains, the starch is protected inside the plant cell walls. The grinding action of the gizzard breaks these cell walls and exposes the starch to digestive enzymes. When feed is finely ground before it reaches the bird, the starch is already exposed, but the rapid passage rate can reduce overall digestion efficiency.

Pellet Quality for Broilers

Pelleting is the most common way to improve broiler performance through feed form. The benefits of pelleting are well established. Birds on pelleted feed eat more, gain weight faster, and convert feed more efficiently than birds on mash. The key is pellet quality.

Pellet quality is measured by two main factors: pellet durability and fines percentage. Pellet durability refers to how well the pellets hold together during handling, transport, and feeding. Fines are the small particles that break off pellets and accumulate in the feeder.

High quality pellets have a durability score above 80 percent and a fines percentage below 10 percent. Low quality pellets crumble easily and produce high levels of fines. When fines exceed 20 percent, the benefits of pelleting are largely lost because birds are effectively eating a mix of pellets and mash.

Fines are a problem for several reasons. Birds eat fewer fines, so high fines levels reduce total feed intake. Fines also accumulate at the bottom of feeders, where they can become stale or moldy. This creates a health risk and leads to feed waste.

Several factors affect pellet quality:

Ingredient composition. Some ingredients bind better than others. Wheat and barley produce more durable pellets than corn. Adding a small amount of fat or molasses can improve binding, but too much fat reduces pellet quality.

Grind size. A medium grind produces better pellets than a very fine or very coarse grind. Very fine particles can overheat during conditioning, while very coarse particles do not bind well.

Conditioning temperature and moisture. The feed must be conditioned with steam to reach the right temperature and moisture content before pelleting. This gelatinizes the starch, which acts as a binder. Conditioning at the correct temperature and time is essential for durable pellets.

Die specification. The die hole diameter and length affect pellet density and durability. A longer die produces harder pellets but reduces production rate.

Cooling and drying. Pellets must be cooled and dried after leaving the die. Improper cooling leaves moisture in the pellets, which makes them soft and prone to breakage.

You can assess pellet quality on farm without special equipment. Collect a sample of pellets from the feeder and count the fines by weight. If more than 10 percent of the sample passes through a 2 mm sieve, your pellet quality needs attention. Also check for pellet hardness by pressing a few pellets between your fingers. Good pellets should resist moderate pressure without crumbling.

Broiler Feed Texture and Bird Behavior

Feed texture influences more than just intake and digestion. It also affects bird behavior and welfare. Understanding how birds interact with their feed helps you manage the feeding system better.

Broilers are naturally curious and will peck at feed throughout the day. They do not eat in a few large meals. Instead, they eat many small meals across the day. This feeding pattern means feed must be continuously available and accessible.

When feed is too fine, birds spend more time pecking at dusty material that provides little nutritional value. They may also develop feather pecking or other behavioral problems as they search for more satisfying feed particles. When feed is too coarse, birds may sort through the feed, flicking out particles they do not want and creating waste.

Feed texture also affects water consumption. Birds on pelleted feed drink more water than birds on mash because the dry, dense pellets require more water for swallowing and digestion. This is normal and should be accounted for in your water supply and litter management.

The ideal feed texture is one that birds can eat easily, without sorting, and that keeps the digestive system working properly. For mash feed, this means a particle size distribution that includes a range of sizes, with the majority of particles between 600 and 900 microns. For pelleted feed, this means a durable pellet with minimal fines.

Evaluating Your Current Feed Particle Size

You cannot manage what you do not measure. Evaluating your feed particle size is a simple process that requires basic equipment and a few minutes per sample.

The standard method for measuring particle size is sieve analysis. You need a set of sieves with different mesh sizes, a shaker, and a scale. Sieve sets for feed analysis are available from agricultural supply companies and extension offices.

The procedure is straightforward:

1. Take a representative feed sample of about 100 grams from the feeder or feed line.
2. Stack the sieves in order from largest mesh on top to smallest on the bottom, with a pan underneath to catch the finest particles.
3. Pour the sample into the top sieve and shake for 10 minutes.
4. Weigh the material retained on each sieve and in the pan.
5. Calculate the geometric mean diameter and geometric standard deviation using the standard formula.

The geometric mean diameter is the average particle size. For broiler mash feed, the target is 600 to 900 microns. The geometric standard deviation describes the uniformity of the particles. A lower standard deviation means more uniform particles. A standard deviation below 2.0 is considered acceptable, while values above 2.5 indicate poor uniformity.

You do not need to calculate these values by hand every time. Many feed mills provide particle size analysis with each delivery. If your feed mill does not offer this service, your local extension office can often test samples for you.

For pelleted feed, the evaluation is different. You are less concerned with the particle size inside the pellet and more concerned with the pellet quality. The key measurements are:

Fines percentage. Sieve a sample of pellets and weigh the fines that pass through a sieve slightly smaller than the pellet diameter. Fines should be below 10 percent.

Pellet durability index. This test requires a durability tester, which tumbles the pellets and measures how much survives. A simpler on farm test is to place a sample in a bucket, shake it vigorously for one minute, and sieve again. The fines percentage after shaking gives you a rough durability estimate.

Pellet hardness. This is a subjective test. Press pellets between your fingers or against a hard surface. A good pellet resists breaking.

Step-by-Step Guide to Adjusting Feed Particle Size

If your feed particle size is outside the target range, or if you are seeing performance problems that you suspect are feed related, follow this step by step process.

Step 1: Confirm the problem. Before making any changes, verify that feed particle size is actually the issue. Look for the common signs: reduced feed intake, poor weight gain, wet litter, feed sorting, or excessive fines in the feeder. Rule out other causes such as disease, heat stress, or water problems first.

Step 2: Test your current feed. Take samples from several feeders and locations in the house. Test each sample for particle size distribution or fines percentage. This gives you a baseline and confirms whether feed form is contributing to the problem.

Step 3: Identify the cause. If particle size is off, determine why. Was the feed mill grind setting changed? Did the pellet mill have a problem? Was the feed damaged during transport or handling? Check your feed delivery records and talk to your feed supplier.

Step 4: Work with your feed supplier. Do not try to fix particle size problems on your own if you buy feed from a commercial mill. Discuss your findings with the mill nutritionist and ask for adjustments. Provide them with your test results so they can make informed changes.

Step 5: Consider feed form changes. If you are feeding mash and struggling with intake, consider switching to crumbles or pellets. If you are already feeding pellets but seeing high fines, ask for a more durable pellet or adjust your handling system to reduce breakage.

Step 6: Make changes gradually. If you change feed form or particle size, do it over several days. Sudden changes can cause a temporary drop in intake while birds adjust. Mix old and new feed together, gradually increasing the proportion of new feed.

Step 7: Monitor the response. After making changes, track feed intake, weight gain, and feed conversion for at least two weeks. Compare the results to your baseline. Watch for improvements in litter quality and bird uniformity.

Step 8: Keep records. Document the particle size of every feed delivery, the results of your tests, and any changes you make. This record helps you identify patterns and makes it easier to diagnose future problems.

Common Mistakes in Managing Feed Particle Size

Many broiler growers make avoidable mistakes with feed particle size. Understanding these common errors helps you avoid them.

Grinding too fine. This is the most common mistake. Fine grinding produces a dusty, flour like feed that birds eat poorly. It also weakens gizzard function and speeds up digesta passage. The result is lower feed intake, poorer digestion, and worse feed conversion. Some growers grind fine because they believe it improves nutrient availability, but the opposite is true for broilers.

Ignoring fines in pellets. Pellets can have high fines levels without the grower noticing. Fines accumulate at the bottom of feeders and in feed lines, where they go unnoticed until they cause problems. Check fines regularly, especially after feed deliveries and during hot weather when pellets may become more fragile.

Not testing particle size. Many growers never measure their feed particle size. They assume the feed mill is producing consistent feed, which is not always true. Grind settings drift, dies wear, and ingredient changes affect particle size. Regular testing catches these problems early.

Sorting by birds. When mash feed has a wide particle size range, birds sort out the larger particles and leave the fines. This means the feed they actually consume is different from what the nutritionist formulated. The result is imbalanced nutrient intake and poor performance.

Changing feed form without adjustment. Switching from mash to pellets or from pellets to crumbles changes intake patterns. Birds on pellets eat more and grow faster, but they also need more water and produce more manure. Failure to adjust water supply and ventilation can cause problems.

Forgetting about the feed system. Feed particle size does not matter if the feed cannot reach the birds. Blocked feed lines, worn augers, and poorly adjusted feeders cause feed to accumulate or separate. Check your feed delivery system regularly for wear and blockages.

Ignoring ingredient variability. The particle size of a feed batch depends on the ingredients used. Different grain sources grind differently. If your feed mill changes grain suppliers, particle size can change even if the mill settings stay the same.

Decision Thresholds for Feed Particle Size

Knowing when to act is as important as knowing what to do. Use these thresholds to guide your decisions.

Mash feed geometric mean diameter below 600 microns. This is too fine. Birds will have reduced intake and poorer digestion. Contact your feed mill and request a coarser grind. If the problem persists, consider switching to crumbles or pellets.

Mash feed geometric mean diameter above 900 microns. This is too coarse for young chicks, though older broilers can handle coarser particles. If the feed contains many whole grain pieces, birds may sort and waste feed. Ask the mill to adjust the grind.

Geometric standard deviation above 2.5. This indicates poor uniformity. The feed contains both very fine and very coarse particles, which encourages sorting. Request a more uniform grind.

Pellet fines above 10 percent. This is the threshold where pellet benefits start to decline. Monitor closely and check for handling damage.

Pellet fines above 20 percent. This is a serious problem. Birds are effectively eating a mix of pellets and mash, and the benefits of pelleting are largely lost. Take action immediately. Request higher durability pellets or change your handling system.

Feed intake drop of more than 5 percent. If feed intake drops suddenly and you cannot explain it by disease, heat, or water problems, check feed particle size. A change in feed form or particle size is a common cause.

Feed conversion deterioration of more than 3 percent. If your feed conversion worsens without an obvious cause, evaluate feed particle size and pellet quality. Poor particle size reduces nutrient digestibility and increases maintenance energy costs.

Wet litter that correlates with feed changes. If wet litter appears shortly after a feed delivery or feed form change, particle size may be the cause. Fine particles speed up digesta passage, which can lead to wetter manure.

Monitoring and Recordkeeping

A simple monitoring system helps you catch particle size problems before they cost you money. Set up a routine that fits your operation size.

Daily checks. Look at the feed in your feeders every day. Check for fines accumulation, dust, and signs of sorting. Feel the feed to assess its texture. This takes seconds but catches obvious problems early.

Weekly checks. Once a week, collect a feed sample from the feeder and examine it closely. Look for pellet breakage, fines, and any changes in appearance. If you see anything unusual, run a fines test.

Delivery checks. Test every feed delivery for particle size or fines before accepting it. This protects you from receiving poor quality feed and gives you a record for disputes.

Monthly analysis. Once a month, send a feed sample to a laboratory for complete analysis. This should include particle size distribution, nutrient content, and pellet quality. Compare the results to the specifications from your feed mill.

Record what matters. Keep a log of every feed delivery, including the date, feed type, batch number, and test results. Record any changes in feed intake, weight gain, or feed conversion. This record helps you identify patterns and makes it easier to work with your nutritionist or extension agent.

Track trends. Do not just record numbers. Look for trends over time. Is pellet quality getting worse as the season progresses? Does particle size vary more in certain months? These trends help you anticipate problems.

Use the data. Share your records with your feed mill and nutritionist. They can use the information to improve their processes and adjust formulations. A grower who provides good data is more valuable to a feed mill than one who only complains about problems.

Troubleshooting Feed Particle Size Problems

When problems arise, work through these troubleshooting steps in order.

Problem: Reduced feed intake. Check the feed in the feeder. Is it dusty? Are there many fines? Is the feed form different from what you ordered? Check water supply and temperature first, then evaluate feed. If the feed looks fine, check for disease signs and consult your veterinarian.

Problem: Poor weight gain. Compare your feed conversion to previous flocks. If it is worse, evaluate feed particle size and pellet quality. Poor digestibility from fine particles or high fines is a common cause. Also check feeder space and adjust feeder height for bird size.

Problem: Wet litter. Wet litter has many causes, including disease, heat stress, and high protein diets. If wet litter appears after a feed change, particle size may be the cause. Fine particles increase digesta passage rate, which increases water in the manure. Check particle size and consider a coarser feed.

Problem: Feed sorting. If birds are leaving fines in the feeder and eating only the larger particles, the feed has poor uniformity. This is more common in mash feed but can also happen with crumbles. Request a more uniform particle size distribution from your mill.

Problem: Excessive fines in the feeder. This indicates pellet quality problems or handling damage. Check the feed delivery system for sharp corners and worn augers that break pellets. Ask your feed mill about pellet durability. Consider using a fines removal system at the feeder.

Problem: Dust in the house. Dusty feed contributes to respiratory problems in birds and workers. It also indicates fine grinding. Check the particle size and request a coarser grind. Improve ventilation to reduce dust levels.

When to Call a Veterinarian or Extension Agent

Most feed particle size problems are manageable on farm. Some situations require professional help.

Call your veterinarian if: You see signs of disease that could be related to feed, such as impacted crops, severe wet litter, or respiratory distress. You suspect mold or mycotoxin contamination in the feed. Birds are dying and you cannot determine the cause. Your veterinarian can help you distinguish feed related problems from disease problems.

Call your extension agent if: You need help testing feed particle size or interpreting results. You are considering a change in feed form and want guidance. You are having persistent problems with feed quality from your mill and need help resolving the issue. Your extension agent can provide technical support and connect you with other experts.

Call your nutritionist if: You want to adjust your feeding program but need formulation advice. You are considering changing feed forms or ingredients. You want to optimize feed particle size for your specific operation. Your nutritionist can help you balance the many factors that affect broiler performance.

Work with your feed mill. The feed mill is your partner in producing quality feed. If you have concerns about particle size or pellet quality, raise them with the mill. Most mills want to produce good feed and will work with you to solve problems. Provide them with data and be specific about what you need.

Feeding Strategies for Different Growth Stages

Broiler nutritional needs change as birds grow. Particle size needs also change, though the principles remain the same.

Starter phase (0 to 10 days). Young chicks have small beaks and immature digestive systems. They need feed that is easy to pick up and digest. Crumbles are ideal for this stage. If you feed mash, use a fine to medium grind, but not so fine that it becomes dusty. The gizzard is developing during this period, so some coarse particles are beneficial.

Grower phase (11 to 24 days). Birds are growing rapidly and feed intake is increasing. Pellets are appropriate at this stage. The gizzard is now fully functional and benefits from the coarse grinding work that pellets provide. Pellet quality matters more than ever because birds are consuming large volumes of feed.

Finisher phase (25 days to market). Feed intake is at its peak and the focus is on efficiency. High quality pellets with minimal fines maximize intake and feed conversion. Some growers use a coarser grind in the finisher feed to slow passage rate and improve digestion. This can be beneficial if pellet quality is good.

Transition between feeds. When changing from starter to grower or grower to finisher, do not change abruptly. Mix the two feeds over several days, gradually increasing the proportion of the new feed. This gives the digestive system time to adapt and prevents intake drops.

The Relationship Between Particle Size and Feed Processing

Understanding how feed is processed helps you understand why particle size varies and what you can do about it.

Grinding. The first step in feed processing is grinding the grain. Hammer mills and roller mills are the two main options. Hammer mills produce a wider range of particle sizes, while roller mills produce a more uniform product. Many mills use a combination of both to achieve the desired particle size distribution.

Mixing. After grinding, ingredients are mixed together. The mixing process can break down some particles, especially if mixing time is excessive. Overmixing can also cause ingredient separation, which affects nutrient uniformity.

Conditioning. In pellet production, the feed is conditioned with steam before pelleting. This adds moisture and heat, which gelatinizes starch and activates binders. Conditioning time and temperature affect pellet quality and nutrient digestibility.

Pelleting. The conditioned feed is forced through a die under high pressure. The die hole size and shape determine pellet diameter. The pressure and temperature during pelleting affect pellet hardness and durability.

Cooling and drying. Pellets are hot and moist when they leave the die. They must be cooled and dried to prevent spoilage and improve durability. Improper cooling leaves pellets soft and prone to breakage.

Handling and storage. Feed handling from the mill to the farm can damage pellets. Pneumatic conveying systems, augers, and drop points all break pellets. Minimize handling and use gentle conveying systems to preserve pellet quality.

Economic Considerations of Feed Particle Size

Feed is the largest cost in broiler production, typically accounting for 60 to 70 percent of total production costs. Small improvements in feed efficiency have a large impact on profitability.

Improving particle size from poor to good can improve feed conversion by 3 to 5 percent. On a flock of 20,000 birds with a feed conversion of 1.7, a 4 percent improvement means saving about 14 tons of feed. At current feed prices, this is a significant saving.

The cost of improving particle size is minimal. Testing feed samples costs little. Working with your feed mill to adjust grind settings costs nothing. The main investment is your time and attention.

Pellet quality also has economic implications. High quality pellets increase feed intake and weight gain, which means birds reach market weight sooner. This reduces the number of days you are feeding birds and improves house turnover. It also reduces the risk of birds going over weight and incurring penalties.

Feed waste is another economic factor. Fine particles and fines are more likely to be wasted than intact pellets. Birds flick dusty feed out of the feeder, and fines accumulate in areas where birds cannot reach them. Reducing waste through better particle size management saves money directly.

Environmental and Health Considerations

Feed particle size affects more than bird performance. It also affects the environment and bird health.

Ammonia emissions. Wet litter produces more ammonia, which harms bird health and worker safety. Fine particles increase digesta passage rate, which leads to wetter manure and higher ammonia levels. Improving particle size helps keep litter drier and reduces ammonia.

Dust control. Fine feed particles contribute to dust in the house. Dust carries bacteria and can cause respiratory problems in birds and workers. Coarser feed reduces dust levels and improves air quality.

Foot health. Wet litter from poor digestion increases the risk of footpad dermatitis and hock burns. These conditions reduce bird welfare and can lead to carcass condemnations at processing. Better particle size reduces wet litter and improves foot health.

Gastrointestinal health. A well developed gizzard and appropriate digesta passage rate support a healthy gut. When feed passes too quickly, undigested nutrients reach the lower gut, where they feed harmful bacteria. This can lead to dysbiosis and enteritis. Coarser particles help maintain a healthy gut environment.

Mold and mycotoxins. Fines accumulate in feeders and can become stale or moldy, especially in humid conditions. Moldy feed poses a health risk to birds. Regular removal of fines from feeders reduces this risk.

Case Scenarios and Practical Examples

These scenarios illustrate common particle size problems and their solutions.

Scenario 1: The dusty mash problem. A grower notices that feed intake has dropped by 8 percent in a flock of 14 day old broilers. The feed is mash and looks very dusty. A sieve analysis shows a geometric mean diameter of 450 microns, well below the 600 micron minimum. The grower contacts the feed mill and requests a coarser grind. The mill adjusts the hammer mill screen size and the next delivery tests at 750 microns. Feed intake recovers within three days.

Scenario 2: The pellet fines issue. A grower feeds pelleted feed but notices that the feeder pans are full of fine particles. A fines test shows 18 percent fines, well above the 10 percent threshold. The grower checks the feed delivery system and finds a worn auger that is crushing pellets. The auger is replaced and feed handling is adjusted to reduce drop height. Fines drop to 6 percent and weight gain improves.

Scenario 3: The sorting flock. A grower sees birds flicking feed out of the feeder and leaving piles of fine particles on the floor. The feed is mash with a wide particle size distribution. A sieve analysis shows a geometric standard deviation of 3.1, indicating poor uniformity. The grower asks the feed mill to use a roller mill instead of a hammer mill for a more uniform grind. The standard deviation drops to 2.0 and sorting behavior stops.

Scenario 4: The wet litter mystery. A grower has wet litter problems that started after a feed change. The new feed is a finer grind than the previous feed. The grower tests the feed and finds a geometric mean diameter of 520 microns. The grower works with the nutritionist to adjust the formulation and grind size. The next feed tests at 700 microns and litter moisture improves within a week.

Frequently Asked Questions

What is the ideal particle size for broiler mash feed?

The target geometric mean diameter for broiler mash feed is 600 to 900 microns. This range provides enough coarse material for gizzard function while still being fine enough for young chicks to eat. The geometric standard deviation should be below 2.0 for good uniformity. If your feed tests below 600 microns or above 900 microns, work with your feed mill to adjust the grind.

Do broilers need pellets or is mash feed acceptable?

Broilers can grow successfully on either form, but pellets generally produce better performance. Birds on pelleted feed eat more, gain weight faster, and convert feed more efficiently than birds on mash. The pelleting process also improves starch digestibility and prevents feed sorting. If you feed mash, pay careful attention to particle size and uniformity to maximize intake and digestion.

Why does my feed have so many fines and what can I do about it?

Fines come from two sources: poor pellet quality at the mill and damage during handling. Test the fines percentage at delivery to check mill quality. If fines are high at delivery, ask the mill to improve pellet durability. If fines increase between delivery and the feeder, check your handling system for worn augers, sharp corners, and excessive drop heights. Install fines removal systems at the feeder if the problem persists.

How does particle size affect gizzard development?

The gizzard is a muscular organ that grinds feed. It develops in response to work. Coarse particles stimulate the gizzard muscles to contract strongly, which leads to a larger, more developed gizzard. A well developed gizzard grinds feed more effectively and improves nutrient digestion. Fine particles give the gizzard little work, which leads to a smaller, weaker gizzard and poorer digestion.

Can I test feed particle size on my farm without expensive equipment?

Yes. You need a set of sieves, a shaker, and a scale. Basic sieve sets are available from agricultural supply companies for a reasonable cost. You can also improvise by using a single sieve to check fines percentage in pelleted feed. For a more complete analysis, send samples to a laboratory or your local extension office. Many feed mills also provide particle size analysis with each delivery.

My birds are eating less since I changed feed. Could particle size be the problem?

Yes, a change in particle size or feed form can reduce intake. Birds prefer larger particles and will eat less of fine, dusty feed. If you changed from pellets to mash or from coarse to fine grind, this could explain the intake drop. Check the feed in your feeders for dust and fines. Test the particle size and compare it to your previous feed. If the feed is too fine, work with your mill to adjust the grind.

How often should I check feed particle size?

Check every feed delivery for basic quality, including fines percentage and visual appearance. Do a full sieve analysis at least monthly, or more often if you are having performance problems. Keep records of all tests and compare results over time. This helps you identify trends and catch problems early before they cost you money.

What should I do if I suspect my feed mill is producing inconsistent particle size?

Document the problem with data. Test multiple samples and record the results. Contact the mill and share your findings. Most mills want to produce consistent feed and will work with you to fix the problem. If the mill does not respond, contact your extension agent for assistance. You may also consider switching to a different feed supplier if the problem persists.

Related Farming Guides

This article is part of a library of broiler management guides. Related topics include broiler nutrition fundamentals, feed management for optimal growth, poultry house environmental control, and broiler health management. Additional guides on feed formulation, water quality, and litter management are available in the poultry section of this site.

Related Clinical & Scientific Guides

• Poultry Farm Fencing: Materials, Design, and Predator Exclusion
• Broiler House Wind Speed and Airflow Measurement
• Broiler House Heating Systems: Types and Efficiency

References

• FAO Poultry Production: https://www.fao.org/poultry-production-products/en/
• USDA APHIS Poultry Health: https://www.aphis.usda.gov/livestock-poultry-disease/avian
• WOAH Avian Influenza: https://www.woah.org/en/disease/avian-influenza/
• 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.