Feed Particle Size and Form for Laying Hens

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

Key Takeaways

• Mash feed with a geometric mean particle size (GMPS) of 1,200 to 1,500 microns is recommended for laying hens to promote gizzard health and prevent obesity; deviations can lead to reduced nutrient digestibility or excessive weight gain.
• Feed particle size uniformity, measured by geometric standard deviation (GSD), is critical; a GSD below 2.0 minimizes selective feeding, preventing nutrient imbalances and feed wastage.
• Pellets and crumbles increase feed intake rate, potentially causing obesity in laying hens on unrestricted feeding programs, but can be beneficial for young pullets or during periods of reduced intake.
• Fine grinding reduces gizzard muscularity and function, potentially increasing digestive issues and behavioral problems like vent and feather pecking; conversely, whole grain feeding can enhance gizzard health and reduce feed costs when implemented correctly.
• On-farm evaluation of particle size using sieve analysis (measuring GMPS and GSD) and regular monitoring (at least monthly) are essential for maintaining optimal feed texture and flock performance.
• Whole grain inclusion, particularly wheat or barley mixed thoroughly with supplements, stimulates gizzard activity and can improve nutrient utilization by 2-5%, but requires gradual introduction and provision of insoluble grit.

Feed represents the largest single cost in most commercial egg production operations, often accounting for 60 to 70 percent of total production expenses. Yet many flock managers focus almost entirely on the nutrient content of the ration while giving little thought to how that feed is processed and presented to the birds. The physical form of feed, including particle size, uniformity, and whether it is served as mash, crumble, or pellet, directly influences how much feed hens consume, how well they digest it, how much they waste, and ultimately how many eggs they produce. This guide explains the science behind feed particle size and form for laying hens, provides practical guidance for evaluating and adjusting your feeding program, and helps you troubleshoot common problems related to feed texture. It is written for small and mid-sized flock owners, commercial egg producers, farm managers, and poultry advisers who want to make better feed management decisions.

At a Glance

• Mash feed with a coarse, uniform particle size is the standard recommendation for most laying hen flocks. Target a geometric mean particle size of 1,200 to 1,500 microns for the complete diet.
• Pellets and crumbles are not generally recommended for laying hens on restricted feeding programs because they increase feed intake and can lead to obesity, but they can be useful for very young pullets or when feed intake needs a boost.
• Feed form affects feed intake more than any other single factor. Hens eat less of a pelleted diet by weight but consume more energy overall, which can lead to excess weight gain.
• Particle size uniformity matters as much as average particle size. A mixture of very fine and very coarse particles allows hens to selectively sort their feed, which can lead to nutrient imbalances.
• Fine grinding reduces gizzard function and can increase the incidence of digestive problems including vent picking and feather pecking in some flocks.
• Whole grain feeding or adding whole grains to mash can improve gizzard health and reduce feed cost without hurting egg production when done correctly.
• Monitor feed particle size at least monthly and after any change in ingredient sourcing or mill settings.
• Consult your extension poultry specialist or nutritionist before making major changes to feed form or particle size, especially in commercial flocks.

Why Feed Particle Size and Form Matter

The physical characteristics of feed influence bird behavior, digestive physiology, nutrient utilization, and flock performance in ways that are often underestimated. Understanding these relationships helps you make better decisions about feed purchasing, on-farm grinding, and feeding management.

The Role of the Gizzard in Digestion

Chickens do not have teeth. Instead, they rely on their gizzard, a highly muscular organ, to grind feed into particles small enough for enzymatic digestion in the small intestine. The gizzard accomplishes this through strong muscular contractions that crush and shear feed particles against one another and against grit or insoluble material in the diet.

The gizzard functions best when it has something substantial to work on. Coarse particles, including whole or cracked grains, stimulate gizzard development and maintain the muscular tone of the organ. When hens receive finely ground feed, the gizzard has little work to do, and it shrinks in size and strength over time. A well-developed gizzard improves nutrient digestibility, reduces the incidence of digestive disorders, and may even contribute to better flock behavior because birds spend more time feeding and less time engaging in harmful behaviors like feather pecking.

Research on gizzard function has shown that particle size directly affects the rate of feed passage through the digestive tract. Coarse particles are retained longer in the gizzard, which allows more time for enzymatic action and nutrient absorption. Fine particles pass through more quickly, which can reduce the digestibility of some nutrients, particularly phosphorus and certain amino acids.

Feed Form and Feed Intake

The form of feed, whether mash, crumble, or pellet, is the strongest single factor influencing feed intake in laying hens. Birds consume pelleted feed more rapidly than mash because pellets are easier to pick up and swallow. This higher intake rate means hens spend less time at the feeder, which can be beneficial in some situations but problematic in others.

For laying hens on an unrestricted feeding program, the higher intake associated with pellets can lead to excessive energy consumption and obesity. Overweight hens lay fewer eggs, produce more shell quality problems, and are more susceptible to heat stress and fatty liver syndrome. For this reason, most commercial laying hen nutritionists recommend mash feed for flocks that are allowed to eat freely.

Pellets and crumbles do have a place in certain situations. Young pullets often struggle to consume enough mash feed to meet their energy needs, particularly in the first few weeks of life. A crumble or mini-pellet can help these birds get a strong start. Similarly, flocks that are experiencing a drop in feed intake due to heat stress, disease, or other factors may benefit from a temporary switch to crumbles or pellets to maintain nutrient intake.

Particle Size and Selective Feeding

Hens are selective feeders. When offered a mixture of particles of different sizes, they will preferentially consume the larger particles and leave the finer material behind. This behavior has important implications for feed management.

If the coarse and fine fractions of a feed have different nutrient compositions, selective feeding can lead to nutrient imbalances. This is particularly problematic when the diet contains added vitamins, minerals, or amino acids in a premix that is much finer than the grain portion of the diet. Hens that eat mostly the coarse fraction may consume adequate energy but insufficient vitamins and minerals, leading to deficiencies over time.

Even when the nutrient composition is similar across particle sizes, selective feeding can create problems with feed wastage. Hens that continuously sort their feed will often flick the less preferred fine particles out of the feeder and onto the floor, where they are lost. This behavior can add up to significant feed losses over the course of a production cycle.

The solution is to produce feed with a uniform particle size distribution. When all particles are similar in size, hens have no basis for selection, and they consume a nutritionally complete diet. Achieving uniformity requires careful attention to grinding, mixing, and the particle size of individual ingredients.

Understanding Particle Size Measurements

Particle size is measured in microns, with 1,000 microns equal to 1 millimeter. The most common method for evaluating particle size in poultry feed is sieve analysis, which involves shaking a feed sample through a series of stacked screens with progressively smaller openings.

Geometric Mean Particle Size

The geometric mean particle size, often abbreviated as GMPS, is the standard statistic used to describe the average particle size of a feed sample. It is calculated using the weights of material retained on each sieve and is expressed in microns. For laying hen mash diets, the recommended GMPS is typically 1,200 to 1,500 microns.

This recommendation reflects a balance between several competing factors. Coarser particles promote gizzard health and improve digestibility, but very coarse particles can make it difficult for hens to consume enough feed to meet their energy needs. Finer particles are easier to consume but reduce gizzard function and may increase the risk of digestive problems.

Particle Size Uniformity

The geometric standard deviation, often abbreviated as GSD, describes the variability in particle sizes within a sample. A lower GSD indicates a more uniform particle size distribution. For laying hen feeds, a GSD below 2.0 is generally considered acceptable, while values above 2.5 indicate excessive variability that may lead to selective feeding.

Achieving a low GSD requires consistent grinding and thorough mixing. Hammer mill screen size, hammer speed, and the moisture content of the grain all influence the particle size distribution produced by the mill. Regular maintenance of grinding equipment is essential for maintaining uniformity.

Evaluating Particle Size On-Farm

You do not need a laboratory to get a reasonable estimate of your feed particle size. A simple set of sieves can be purchased from agricultural supply companies, and the testing procedure is straightforward. Here is a practical method for on-farm particle size evaluation:

1. Collect a representative sample of feed from several locations in the feeder or feed bin. Take at least one cup of feed for testing.
2. Stack the sieves in order, with the coarsest on top and a pan on the bottom. A basic set might include sieves with openings of 2,000, 1,000, 500, and 250 microns.
3. Pour the feed sample onto the top sieve and shake the stack vigorously for about two minutes. An automatic sieve shaker gives more consistent results, but hand shaking works acceptably.
4. Weigh the material retained on each sieve and on the pan. Calculate the percentage of the total weight represented by each fraction.
5. Use a particle size calculator or a simple spreadsheet to determine the geometric mean particle size and standard deviation. Many extension services provide free calculators online.

For a quick field check, you can simply look at the distribution of particles on the sieves. A good laying hen mash should have visible coarse particles throughout, with very little fine dust. If the feed looks like flour or has a large amount of fine material at the bottom of the feeder, the particle size is likely too fine.

Mash vs Crumble vs Pellet for Laying Hens

The three main feed forms available to poultry producers are mash, crumble, and pellet. Each has distinct advantages and disadvantages for laying hen operations.

Mash Feed

Mash is the traditional form of poultry feed and consists of ground ingredients mixed together without any further processing. It is the most economical feed form to produce because it requires no additional equipment beyond grinding and mixing.

For laying hens, mash has several important advantages. It allows birds to express natural feeding behaviors, including scratching and sorting. The slower rate of intake associated with mash helps prevent overconsumption and obesity. Mash feed is also easier to modify than pellets or crumbles when you need to incorporate medications or supplements.

The main disadvantage of mash is the potential for selective feeding and ingredient separation. This problem can be minimized by producing a uniform particle size and by adding a small amount of fat or molasses to help fine particles adhere to coarser ones. Some producers also use pellet binders in mash feeds to reduce separation during handling.

Another consideration with mash is feed wastage. Hens can be messy eaters, and fine particles are easily spilled or blown away by fans. Using feeders with proper lip height and adjusting feeder fill levels can help reduce this waste.

Pelleted Feed

Pelleting involves compressing mash feed through a die under heat and pressure to form dense cylinders of uniform size. The process improves feed handling characteristics, reduces dust, and increases the bulk density of the feed, which reduces transportation and storage costs.

For laying hens, the primary concern with pellets is increased feed intake. Because pellets are consumed more rapidly than mash, hens on unrestricted feeding will eat more and gain excess weight. This is why most commercial layer operations use mash rather than pellets.

Pellet quality varies widely depending on the formulation and the pelleting process. High quality pellets are durable and resist breaking into fines during handling. Poor quality pellets may crumble into a mixture of pellets and fine particles, which can actually make selective feeding worse than with mash.

If you choose to feed pellets to laying hens, look for pellets that are 3 to 4 millimeters in diameter and that hold their shape well. Monitor body weights closely and be prepared to restrict feed intake if hens begin gaining excess weight.

Crumbled Feed

Crumbles are pellets that have been broken into smaller pieces. They combine some of the advantages of pellets, including reduced dust and improved handling, with a smaller particle size that is more appropriate for smaller birds.

Crumbles are commonly used for pullets and for hens during the early stages of lay. They are also useful for encouraging feed intake in stressed or sick flocks. However, crumbles have the same potential to increase feed intake as pellets, so they should be used with caution in mature laying hens.

The particle size of crumbles is more variable than that of either mash or whole pellets. Some crumbles will be relatively fine, while others may be quite coarse. This variability can contribute to selective feeding, so it is important to monitor how the crumbles hold up during handling and feeding.

Making the Choice for Your Flock

For most laying hen flocks, a high quality mash with a coarse, uniform particle size is the best choice. It supports digestive health, prevents obesity, and is the most economical option. Use crumbles or pellets only when you have a specific reason, such as improving intake in young pullets or boosting consumption during heat stress.

If you are feeding a commercial complete feed, ask your feed supplier about the particle size of their mash products. Many companies offer different grinds for different species and ages, and they can adjust the grind to meet your needs. If you are grinding your own feed, pay close attention to mill settings and screen sizes to achieve the recommended particle size.

Whole Grain Feeding for Laying Hens

An alternative to feeding all feed in a processed form is to include whole grains in the diet. This practice has gained popularity in recent years, particularly among producers looking to reduce feed costs and improve bird health.

How Whole Grain Feeding Works

The concept is simple. Instead of grinding all the grain in the diet, a portion of the grain is left whole and mixed with a concentrated supplement or a coarsely ground base mix. The whole grain provides energy and stimulates gizzard activity, while the supplement provides the protein, vitamins, and minerals the birds need.

Whole grain feeding is most commonly practiced with wheat, though barley, oats, and even corn can be used. The grain can be mixed into the complete feed at the mill, or it can be offered separately in a second feeder. Some producers use a sequential feeding system where whole grain and supplement are offered at different times of day.

Benefits of Whole Grains

The main benefit of whole grain feeding is improved gizzard health. Birds that consume whole grains develop larger, more muscular gizzards, which improves the digestibility of the entire diet. Some studies have shown improvements in nutrient utilization of 2 to 5 percent when whole grains are included.

Whole grains can also reduce feed cost. When you purchase whole grain separately and mix it with a concentrated supplement, you may save money compared to buying a complete feed. The savings depend on local grain prices and the cost of the supplement, but they can be significant for larger flocks.

Behavioral benefits are another consideration. Birds that spend more time feeding and foraging tend to have lower rates of feather pecking and other harmful behaviors. Whole grains increase feeding time because they require more effort to consume and grind.

Risks and Limitations

Whole grain feeding is not without risks. The most important concern is that hens will selectively consume the whole grain and leave the supplement, leading to nutrient imbalances. This is less of a problem when the grain is thoroughly mixed into the feed, but it can be significant when the two components are offered separately.

Another concern is that whole grains may reduce feed intake in the short term. Hens need time to adapt to the new feed form, and some birds may not consume enough during the transition period. Introduce whole grains gradually, over a period of one to two weeks, to allow the birds to adjust.

Whole grain feeding is not appropriate for all situations. Young pullets, birds under stress, and flocks with a history of poor feed intake may not do well on diets with high levels of whole grain. Start with a modest inclusion rate of 10 to 20 percent whole grain and monitor performance closely before increasing the level.

Implementing Whole Grain Feeding

If you want to try whole grain feeding, work with your nutritionist to develop a feeding program that meets your flock's needs. Here are some practical guidelines:

1. Start with wheat or barley, which are easier for hens to crack than corn. If you use corn, consider cracking it rather than leaving it whole.
2. Mix the whole grain thoroughly with the supplement or base mix. Aim for a uniform distribution throughout the feed.
3. Introduce whole grains gradually over 7 to 14 days. Start with 5 percent of the diet and increase by 5 percent increments.
4. Monitor feed intake and body weight closely during the transition. Hens should maintain or slightly increase their feed intake.
5. Provide insoluble grit to help the gizzard grind the whole grain. Offer grit free choice in a separate feeder.
6. Observe the flock for signs of selective feeding. If you see large amounts of supplement left in the feeder while the grain disappears, reduce the whole grain level or improve the mixing.

Practical Steps for Optimizing Feed Particle Size

Whether you purchase commercial feed or grind your own, there are several practical steps you can take to ensure your hens receive feed with an appropriate particle size.

If You Purchase Commercial Feed

Commercial feed mills produce mash feeds with a range of particle sizes depending on their equipment and settings. When ordering feed, ask the mill for their particle size specifications. Many mills can provide a sieve analysis of their products upon request.

Request a coarse grind for your laying hen feed. Specify that you want a geometric mean particle size of at least 1,200 microns. If the mill cannot provide this, consider looking for another supplier or supplementing the feed with whole grains.

Check each delivery for consistency. Feed can vary from batch to batch, and you want to catch any problems before they affect your flock. Take a sample from each delivery and compare it visually with previous deliveries. If you notice a significant change in texture, contact the mill.

If You Grind Your Own Feed

Producing feed on-farm gives you complete control over particle size, but it also requires careful attention to equipment and procedures. Here are the key factors that influence particle size in a hammer mill:

Screen size. The opening size of the mill screen is the primary factor controlling particle size. For laying hen feed, use a screen with openings of 6 to 8 millimeters. This is much coarser than what is typically used for broiler feed, which often uses screens of 3 millimeters or less.

Hammer speed. Higher hammer speeds produce finer particles. For a coarse grind, operate the mill at a lower speed if possible. This also reduces energy consumption and wear on the mill.

Hammer condition. Worn hammers produce a wider range of particle sizes and more fines. Inspect hammers regularly and replace them when they show significant wear. The edges of the hammers should be sharp and square.

Grain moisture. Grains with higher moisture content produce coarser particles and more variability. If your grain is particularly dry, you may need to adjust your screen size or hammer speed to achieve the desired particle size.

Airflow. The amount of air moving through the mill affects particle size and mill capacity. Too much airflow can pull fine particles through the screen prematurely, increasing the proportion of fines in the finished feed.

After grinding, evaluate the particle size of your feed using the sieve method described earlier. Adjust your mill settings as needed to achieve a geometric mean particle size of 1,200 to 1,500 microns with a standard deviation below 2.0.

Mixing Considerations

Proper mixing is essential for producing a uniform feed. Even if the individual ingredients have the correct particle size, poor mixing can result in a feed that varies widely from one location to another in the feeder.

The mixing time depends on the type of mixer you use. Horizontal ribbon mixers typically require 5 to 10 minutes to achieve a uniform mix. Vertical mixers may require longer. Avoid overmixing, which can cause particle segregation and increase the proportion of fines.

Adding liquid ingredients, such as fat or molasses, can help reduce particle segregation. The liquid coats the fine particles and causes them to adhere to coarser particles, creating a more stable mixture. However, too much liquid can cause the feed to cake or bridge in the feeder.

Feeder Management

How you manage feeders can also influence the particle size of the feed your hens actually consume. Feed that sits in a feeder for a long time will accumulate fines at the bottom, and hens will consume the coarser particles first. This can lead to nutrient imbalances and increased feed wastage.

Run feeders on a schedule that keeps feed fresh. Most producers use a timer to run the feeder several times per day, delivering small amounts of feed each time. The goal is to have the feeder empty for a short period each day, which encourages hens to consume all the feed, including the fines.

Adjust feeder height so the lip of the feeder is at the level of the hen's back. This reduces feed wastage and prevents hens from raking feed out of the feeder. Check feeder adjustments regularly, especially as hens age and their body size changes.

Common Mistakes in Feed Particle Size Management

Many flock managers make avoidable errors in feed particle size management. Recognizing these mistakes can help you improve your feeding program.

Grinding Feed Too Finely

The most common mistake is grinding feed too finely. This often happens because producers assume that finer grinding improves digestibility. While this is true to a point, the benefits of fine grinding are outweighed by the negative effects on gizzard health and feed intake.

Fine feed also creates more dust, which can irritate the respiratory systems of both birds and workers. Dusty feed is more likely to be wasted and can accumulate in feeders, where it becomes stale and unpalatable.

If your feed looks like flour or has a large proportion of fine particles, adjust your grinding process to produce a coarser product. This single change can have a significant impact on flock performance.

Ignoring Particle Size Uniformity

Some producers focus only on the average particle size and ignore uniformity. A feed with a geometric mean particle size of 1,300 microns could have a very wide distribution, with some particles as fine as dust and others as large as whole kernels. This type of feed encourages selective feeding and can lead to nutrient imbalances.

Monitor the standard deviation of your feed particle size distribution. If it is above 2.5, take steps to improve uniformity. This may involve adjusting mill settings, improving mixing, or changing the particle size of individual ingredients.

Switching Feed Forms Abruptly

Hens do not adapt well to sudden changes in feed form. A flock that has been eating mash may take several days to adjust to crumbles or pellets, and feed intake may drop during the transition. Conversely, switching from pellets to mash can lead to a temporary increase in feed intake as hens adjust to the different texture.

Make any changes in feed form gradually, over a period of 5 to 7 days. Mix increasing proportions of the new feed with the old feed until the transition is complete. Monitor feed intake and egg production closely during this period.

Assuming All Feed Mills Produce the Same Product

Different feed mills use different equipment and processes, and their products can vary significantly in particle size and uniformity. Even the same mill can produce different grinds on different days depending on grain source, moisture content, and equipment condition.

Do not assume that a feed from one mill is equivalent to a feed from another. Evaluate each delivery and be prepared to adjust your feeding program if the particle size changes.

Neglecting Grit Provision

Birds on coarse mash or whole grain diets need insoluble grit to help the gizzard grind feed. Grit is especially important when hens are housed indoors and do not have access to soil or small stones. Offer granite grit free choice in a separate feeder, and replenish it regularly.

The amount of grit needed depends on the coarseness of the feed. Birds on finely ground feed need little or no grit, while birds on whole grains may consume significant amounts. Monitor grit consumption and adjust as needed.

Monitoring and Recordkeeping

A good feed particle size program requires regular monitoring and careful recordkeeping. Here are the key practices to implement.

Sampling Protocol

Collect feed samples for particle size analysis at least monthly, and more frequently if you have made changes to your grinding or mixing process. Take samples from multiple locations, including the feed bin, the feeder, and the end of the auger or delivery system.

Use a clean container for each sample and label it with the date, time, location, and batch number. If you cannot analyze the sample immediately, store it in a sealed plastic bag in a cool, dry place.

Recording Particle Size Data

Keep a log of particle size measurements for each batch of feed. Record the geometric mean particle size, the standard deviation, and the percentage of fines below 500 microns. Note any changes in ingredients, mill settings, or equipment maintenance that might have affected the results.

This log will help you identify trends and catch problems early. For example, if you notice a gradual increase in the proportion of fine particles, you may need to replace worn hammers or adjust your mill settings.

Tracking Flock Performance

Particle size data is most useful when it is correlated with flock performance. Keep records of feed intake, egg production, egg weight, body weight, and mortality. Note any changes in these parameters that coincide with changes in feed particle size.

A sudden drop in feed intake may indicate that the feed is too coarse or that the particle size distribution has changed. Conversely, an increase in feed intake and body weight may indicate that the feed has become too fine or that the feed form has changed.

Scheduling Reviews

Schedule a formal review of your feed particle size program every six months. Review your particle size logs, flock performance records, and any problems that have occurred. Consider whether changes in your flock, your feed ingredients, or your equipment warrant adjustments to your particle size targets.

Involve your nutritionist or extension agent in these reviews. They can provide valuable perspective on whether your particle size program is aligned with current recommendations and can help you interpret your data.

Troubleshooting Feed Particle Size Problems

When flock performance declines, feed particle size is one of the first things to investigate. Here are some common problems and their likely particle size causes.

Reduced Feed Intake

If hens are eating less than expected, check the particle size of the feed. Feed that is too coarse can be difficult for hens to consume, particularly if they are young or small. Feed that is too fine may be unpalatable or may contain excessive dust.

Also check for selective feeding. If the feeder contains a large amount of fine material at the bottom, hens may be consuming the coarse particles and leaving the fines behind. This can lead to nutrient deficiencies even when the overall feed intake appears adequate.

Increased Feed Wastage

Excessive feed wastage often indicates that the feed contains too many fine particles. Fine feed is easily spilled or blown away by fans, and hens may flick it out of the feeder while searching for larger particles.

Check the feeder adjustment and the fill level. Feeders that are too full encourage wastage, as do feeders that are set at the wrong height. Reduce the feeder fill level and ensure that the feeder lip is at the correct height for the birds.

Poor Egg Production

If egg production declines without an obvious cause, evaluate the particle size of the feed. A change in particle size can affect nutrient intake even when the feed formulation is unchanged. For example, if the feed becomes finer, hens may consume more feed but digest it less efficiently, leading to reduced nutrient availability.

Also consider the possibility of nutrient segregation. If the fine and coarse fractions of the feed have different nutrient compositions, selective feeding can lead to deficiencies of specific nutrients, which can affect egg production.

Increased Feather Pecking and Cannibalism

Behavioral problems like feather pecking are often related to feeding behavior. Hens that are frustrated by feed that is difficult to consume, or that spend insufficient time feeding because the feed is too easy to consume, may redirect their pecking behavior toward other birds.

Coarse mash or whole grain feeding can help reduce these problems by increasing feeding time and providing a more satisfying foraging experience. If you are experiencing behavioral problems, consider whether your feed particle size is appropriate.

Digestive Problems

An increase in digestive problems, including sour crop, impacted gizzard, or diarrhea, can be related to feed particle size. Feed that is too fine reduces gizzard function and can lead to poor digestion. Feed that is too coarse, particularly if it contains large pieces of hard grain, can cause impaction.

If you see digestive problems in your flock, examine the feed for particle size issues. Also check the availability of grit, which is essential for proper gizzard function.

Decision Thresholds for Adjusting Feed Form

Knowing when to adjust your feed form or particle size can help you avoid problems before they become serious. Here are some thresholds to consider.

When to Switch to Crumbles or Pellets

Consider switching to crumbles or pellets in the following situations:

• Pullets under 8 weeks of age that are not consuming enough mash to meet their growth needs.
• Flocks experiencing a drop in feed intake of more than 10 percent due to heat stress, disease, or other factors.
• Flocks that need to gain weight quickly, such as hens that are underweight at the onset of lay.
• Flocks that are being moved or otherwise stressed and need encouragement to eat.

When you make the switch, use the crumble or pellet for a limited period, and return to mash once the situation has resolved. Monitor body weights closely to avoid excessive weight gain.

When to Increase Particle Size

Increase the coarseness of your feed in the following situations:

• Hens are gaining excess weight or becoming obese.
• Feather pecking or cannibalism is a problem.
• Gizzard development appears poor, as indicated by a high incidence of whole grains in the droppings.
• Feed intake is higher than expected for the flock's production level.

You can increase particle size by using a coarser screen in your hammer mill, by adding whole grains to the diet, or by switching to a feed supplier that offers a coarser grind.

When to Decrease Particle Size

Decrease the fineness of your feed in the following situations:

• Young pullets are struggling to consume enough feed.
• Feed intake has dropped and hens are losing weight.
• Hens are showing signs of an impacted crop or gizzard.
• The feed contains an excessive number of very large particles, such as whole corn kernels.

If you need to reduce particle size, do so gradually to give the birds time to adjust. Monitor feed intake closely during the transition.

When to Call for Professional Help

Most feed particle size problems can be resolved with careful attention to grinding, mixing, and feeder management. However, there are times when you should seek professional assistance.

Call your extension poultry specialist or a poultry nutritionist if:

• You cannot achieve the recommended particle size with your current equipment, and you are unsure whether to modify your equipment or change your feed purchasing strategy.
• Flock performance problems persist despite your best efforts to correct particle size issues.
• You are considering a major change to your feeding program, such as switching to whole grain feeding or changing feed suppliers.
• You suspect that your feed may be contaminated or that an ingredient may be causing the problem.

Call your veterinarian if:

• You see signs of disease in your flock, including respiratory distress, diarrhea, or sudden death.
• Digestive problems are severe or are accompanied by other signs of illness.
• You suspect that a nutritional problem has caused secondary health issues, such as fatty liver syndrome or osteoporosis.

Your veterinarian can help you rule out infectious causes of poor performance and can work with your nutritionist to develop a corrective feeding program.

Feed Storage and Handling Considerations

The physical quality of feed can deteriorate during storage and handling, even if the particle size was correct at the time of manufacture. Proper storage and handling practices help maintain feed quality.

Storage Conditions

Store feed in a clean, dry, well-ventilated area. Moisture is the enemy of feed quality, as it promotes mold growth and nutrient degradation. Keep feed off the floor on pallets or in bins, and protect it from rodents and wild birds.

Temperature also affects feed quality. High temperatures accelerate the oxidation of fats and the degradation of vitamins. Store feed in a cool location when possible, and do not allow feed to sit in hot bins for extended periods.

Feed Rotation

Use a first-in, first-out system for feed inventory. Older feed should be used before newer feed to prevent spoilage and nutrient degradation. Label all feed with the delivery date and the date of manufacture if available.

Do not purchase more feed than you can use within a reasonable time. Most complete feeds should be used within 4 to 6 weeks of manufacture. If you are mixing your own feed, grind and mix only what you will use within 7 to 10 days.

Handling Systems

The augers, conveyors, and other equipment used to move feed can affect particle size. Long augers and steep drops can cause feed to break down, increasing the proportion of fines. Minimize the distance that feed travels and avoid excessive drops where possible.

Regularly inspect and maintain your feed handling equipment. Worn augers and damaged conveyors can cause feed to be crushed or ground, altering the particle size distribution. Replace worn parts promptly.

Economic Considerations

Feed particle size and form have direct economic implications beyond the cost of the feed itself. Understanding these economics helps you make better decisions.

Feed Cost vs Feed Efficiency

The cheapest feed is not always the most economical. A feed that costs less per ton but results in poorer feed conversion can actually cost more per dozen eggs produced. When evaluating feed options, consider the cost per unit of egg production, not just the cost per ton.

Coarse mash feeds may be slightly more expensive to produce than fine mash feeds because they require more careful grinding and may have a lower bulk density. However, the improved feed efficiency and better flock health associated with coarse feed can more than offset the additional cost.

Feed Wastage

Feed wastage represents a direct economic loss. A flock that wastes 5 percent of its feed is paying for feed that contributes nothing to production. Reducing wastage through proper feeder management and appropriate particle size can save a significant amount of money over time.

Monitor feed wastage by tracking feed disappearance and comparing it to expected intake. If feed disappearance is consistently higher than expected, investigate the cause. Look for spillage around feeders, holes in feed lines, and excessive fine particles in the litter.

Processing Costs

If you are grinding your own feed, the particle size you choose affects your processing costs. Coarse grinding requires less energy and produces less wear on your equipment than fine grinding. It also increases mill capacity, allowing you to process more feed in less time.

Consider the full cost of processing, including energy, labor, and equipment maintenance, when deciding on your target particle size. In most cases, the savings from coarse grinding more than offset any reduction in feed efficiency.

Special Considerations for Different Production Systems

The optimal feed particle size and form can vary depending on your production system.

Cage Systems

Birds in cage systems have limited ability to express natural foraging behaviors. They rely entirely on the feed provided, and they have no access to litter or soil. This makes feed particle size particularly important in cage systems.

Provide a coarse mash with a uniform particle size to encourage gizzard development and reduce the risk of feather pecking. Ensure that feeders are properly adjusted to minimize wastage, and monitor feed intake closely.

Floor and Free-Range Systems

Birds in floor and free-range systems have more opportunities to forage and may consume insects, vegetation, and grit from their environment. This can supplement their diet and reduce their reliance on the feed provided.

In these systems, you may be able to use a slightly coarser feed or include more whole grains in the diet. However, you still need to ensure that the birds consume a nutritionally complete diet. Monitor body weights and egg production to verify that the birds are getting what they need.

Organic and Specialty Production

Organic and specialty production systems often have restrictions on the types of feed ingredients and processing methods that can be used. Work with your certifier to ensure that any changes to your feed particle size or form comply with the standards for your system.

Some specialty markets prefer eggs from hens fed whole grains or other alternative feed forms. If you are targeting these markets, you may be able to differentiate your product by using a distinctive feeding program. However, ensure that the program still meets the nutritional needs of your flock.

Frequently Asked Questions

Will hens eat less if I feed pellets instead of mash?

Yes, hens typically consume less pelleted feed by weight than mash feed because pellets are more energy-dense and can be consumed more rapidly. However, the total energy intake is often higher with pellets because the birds eat more than they need to meet their energy requirements. This can lead to excessive weight gain, which is why mash is generally recommended for laying hens.

How can I tell if my feed particle size is appropriate without special equipment?

You can get a rough idea by examining a handful of feed. Good layer mash should contain visible coarse particles, roughly the size of a pinhead to a small pea, with relatively little fine dust. If the feed looks like flour or has a large amount of dust at the bottom of the feeder, it is probably too fine. For a more accurate assessment, purchase a set of sieves and perform a simple particle size analysis.

Can I feed whole corn to my laying hens?

Whole corn can be fed to laying hens, but it is not ideal as the sole grain source because the birds may have difficulty cracking the large, hard kernels. Cracked corn or corn that has been coarsely ground is a better option. If you want to feed whole grain, wheat or barley are easier for hens to consume and digest.

How often should I check the particle size of my feed?

Check the particle size at least monthly, and more frequently if you have changed feed suppliers, changed ingredients, or adjusted your grinding equipment. Also, check the particle size of each delivery if you purchase commercial feed, as quality can vary between batches.

My hens are sorting their feed and leaving the fines in the feeder. What should I do?

Selective feeding is usually a sign that the particle size distribution is too wide. Try to improve the uniformity of the feed by adjusting your grinding process or by adding a small amount of fat or molasses to help the fine particles adhere to the coarse ones. Also, check your feeder management. Running the feeder more frequently with smaller amounts of feed can help ensure that all the feed is consumed.

Will adding grit to the diet help with digestion?

Insoluble grit helps the gizzard grind feed, particularly coarse feed and whole grains. If you are feeding a coarse mash or whole grains, provide granite grit free choice in a separate feeder. Birds on finely ground feed generally do not need supplemental grit, but providing it is unlikely to cause harm.

Can feed particle size affect egg shell quality?

Feed particle size can indirectly affect egg shell quality through its influence on calcium intake. If hens are selectively consuming feed, they may not get enough calcium, which can lead to shell quality problems. Also, very fine feed can reduce the digestibility of calcium and other minerals. Ensuring a uniform particle size and adequate calcium intake can help maintain good shell quality.

Should I switch to crumbles when my hens start laying?

Most hens do not need crumbles at the onset of lay. A high quality mash with an appropriate particle size will support the transition to egg production. Crumbles may be useful if hens are not eating enough to support the demands of egg production, but they should be used with caution to avoid excessive weight gain. Monitor body weights and adjust the feeding program as needed.

Related Farming Guides

This section will be populated with links to related farming guides on poultry nutrition, feed management, and egg production. Check back for updates.

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.