# [Broiler Feed Particle Size](/knowledge/animal-farming/poultry/broiler-feed-particle-size-effects-on-intake-and-digestion) and Feed Form Management ## Key Takeaways - Broiler feed form (mash, crumble, pellet) and particle size distribution are critical for digestive efficiency, feed intake, and overall performance, necessitating a phased feeding strategy that aligns with the broiler's age and physiological development. - Coarser particles stimulate gizzard development and mechanical digestion, improving starch digestibility and reducing enteric disorders, while excessive fines (<1 mm) can bypass the gizzard, leading to reduced nutrient utilization and potential issues like wet litter and footpad dermatitis. - Pellet quality, assessed by the Pellet Durability Index (PDI) and percentage of fines, directly impacts feed intake and growth; a PDI above 80-85% is generally acceptable, but adjustments to steam conditioning, retention time, or binders may be required to minimize fines. - Routine sieve analysis (e.g., using a Ro-Tap shaker) to determine geometric mean diameter and coefficient of variation, alongside pellet durability testing, is essential for monitoring and adjusting feed processing parameters to ensure consistency and prevent selective feeding. - Feed form management is integral to biosecurity, as fines can increase dust, facilitating pathogen transmission, and influence gut health by affecting proventricular pH and susceptibility to enteric diseases like necrotic enteritis. - Persistent performance issues coinciding with documented changes in particle size or feed form warrant professional escalation to a nutritionist or feed mill manager, as optimal thresholds vary with ingredient composition, whole grain inclusion, and environmental conditions. --- [Broiler feed particle size](/knowledge/animal-farming/poultry/broiler-feed-particle-size-effects-on-intake-and-digestion) and feed form are critical determinants of digestive efficiency, feed intake, and overall flock performance. The choice among mash, crumble, and pellet forms, combined with the particle size distribution of the ground ingredients, must be managed to match the broiler’s age and physiological development. ## At a Glance | Feed Form | Typical Particle Characteristics | Management Focus | Record-Keeping Elements | |-----------|---------------------------------|------------------|--------------------------| | Mash | Fine to moderate, uniform distribution | Avoid segregation, ensure consistent access | Sieve analysis results, feed consumption | | Crumble | Fragmented pellet, moderate particle size | Balance size for intake and gizzard function | Percentage fines, average particle size | | Pellet | Compacted, durable cylinder | Minimize fines, adjust conditioning parameters | Pellet durability index, bulk density | ## System Context and Planning Decisions Broiler production programs follow a phased feeding strategy: starter (first 7,14 days), grower (until approximately day 21,28), and finisher (last week or more). Each phase imposes distinct requirements for feed particle size and form. Starter feeds are commonly provided as small crumbles or fine mash to facilitate intake by day,old chicks. As the gizzard develops, coarser particles and more durable pellets can be introduced to stimulate mechanical digestion and improve nutrient utilization ([Feed particle size: Implications on the digestion and performance of poultry](https://api.elsevier.com/content/abstract/scopus_id/34748888312)). The decision to transition from one form to another depends on bird weight, feed budget, and mill capability. Feed access is directly influenced by particle form. Pellets that break into a high percentage of fines reduce feed intake and depress growth ([Pelleting of broiler diets: An overview](https://api.elsevier.com/content/abstract/scopus_id/84872875882)). Similarly, mash with a wide particle size distribution can allow selective feeding, leading to nutrient imbalances and variable flock uniformity. Planning must therefore account for the equipment available (roller mill vs. hammer mill) and the desired geometric mean diameter for each phase ([PubMed record 41762973](https://pubmed.ncbi.nlm.nih.gov/41762973/)). ## Core Management Framework A rigorous framework for feed particle size and form management rests on measurement, adjustment, and documentation. Routine sieve analysis provides the particle size distribution of mash or of ground grains before pelleting. This information guides mill roller gap or hammer screen selection and helps maintain consistency across batches. Pellet quality is assessed using the pellet durability index (PDI) and the percentage of fines after handling. A low PDI or high fines fraction signals a need to adjust steam conditioning temperature, retention time, or binder inclusion ([The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens](https://api.elsevier.com/content/abstract/scopus_id/0036730317)). Production records must include daily feed consumption, body weight gain, and [feed conversion ratio](/knowledge/animal-farming/poultry/feed-conversion-ratio-measuring-improving-poultry-efficiency), stratified by feed form and phase. When deviations appear,such as increased feed wastage, reduced intake, or poor uniformity,the particle size profile and pellet quality data should be reviewed before altering formulation or processing parameters. Uncertainty exists because optimal particle size thresholds vary with ingredient composition, whole grain inclusion, and environmental conditions. Professional escalation to a nutritionist or feed mill manager is warranted whenever persistent performance problems coincide with documented changes in particle size or feed form. ## Feed Form and Particle Size Distribution in Broiler Production Feed form,mash, crumble, or pellet,and particle size distribution directly influence broiler performance, gut development, and feed efficiency. Mash diets consist of ground ingredients presented as a loose meal, while pellets are compressed cylinders formed by conditioning and extrusion. Crumble is a pellet that has been deliberately broken into smaller fragments, typically offered during the starter phase. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) notes that pelleting improves feed density and reduces selective feeding, but the process can alter particle size uniformity and nutrient availability. Particle size distribution is measured by sieving ground feed through a series of standard screens (e.g., Ro-Tap shaker) and calculating geometric mean diameter and standard deviation. Research cited in [Feed particle size: Implications on the digestion and performance of poultry](https://api.elsevier.com/content/abstract/scopus_id/34748888312) (2007) explains that coarser particles stimulate gizzard development and enhance gizzard function, which in turn improves starch digestibility and reduces the incidence of enteric disorders. Conversely, excessive fines,particles smaller than 1 mm,bypass the gizzard and may lead to reduced nutrient utilization, wet litter, and footpad dermatitis. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) resources emphasize that feed form selection should match the bird’s age and digestive capacity. In the starter phase (0,10 days), a coarse crumble or a high-quality mini-pellet is often used to ensure uniform intake and ease of consumption. For the grower and finisher phases (11,42 days), whole pellets of 3,4 mm diameter are preferred because they encourage voluntary feed intake and support rapid growth. Birds fed intact pellets typically achieve higher body weights and better feed conversion ratios compared to those fed mash, provided pellet durability is adequate. ## Production-Stage Decisions and Feed Access During the first week of life, broiler chicks have an immature gizzard and limited ability to grind large particles. Providing a crumble with a uniform particle size (1,2 mm) reduces sorting and ensures each bird receives a balanced ration. The [PubMed record 42345221](https://pubmed.ncbi.nlm.nih.gov/42345221/) describes that early exposure to coarse particles can lead to reduced feed intake and uneven growth. As the gizzard develops, particle size should be increased gradually to maintain gizzard function and prevent gizzard erosion. Feed access is equally critical. Insufficient feeder space or poor feeder height adjustment forces birds to compete, leading to uneven feed intake and increased fines generation due to pecking and scattering. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) guidelines recommend a minimum of 2,3 cm of feeder space per bird for pellet feeding and 3,4 cm for mash. Additionally, feeders should be checked daily to ensure feed depth is adequate but not so deep that fines accumulate at the bottom. Fines buildup can promote mold growth and mycotoxin production, as noted in [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) references on feed hygiene. ## Facilities, Environment, and Nutrition Interactions The physical environment interacts with feed form in several ways. High ambient temperature reduces feed intake, and birds offered pellets may consume insufficient energy if pellet quality is poor. Conversely, in cold conditions, mash diets may slow passage rate sufficiently to meet increased energy demands, but this trade-off must be evaluated on a flock-by-flock basis. Lighting programs also affect feeding behavior. A dark period of 4,6 hours encourages the bird to consume more feed during light phases, but if pellets fracture easily, feed wastage increases. Water consumption is directly linked to feed form. Pellets and crumbles are dry and require adequate water intake for proper digestion. The [PubMed record 42291525](https://pubmed.ncbi.nlm.nih.gov/42291525/) reports that birds on pelleted diets may drink more water than those on mash, due to higher osmolality of the digesta. Insufficient water availability,caused by low flow rates, dirty nipples, or inadequate drinker space,can reduce feed intake and increase the risk of dehydration. Producers should monitor water-to-feed ratios daily and adjust as needed, especially when switching feed forms. ## Records, Monitoring, and Practical Assessment Systematic record-keeping is essential for managing feed form and particle size. Daily records should include feed intake (kg per bird), water consumption, body weight gain, and mortality. At least weekly, a particle size analysis of the feed delivered to each house should be performed. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) extension materials advise using a series of four to six sieves (4 mm, 2 mm, 1 mm, 0.5 mm, and pan) to measure geometric mean diameter and the coefficient of variation. A coefficient of variation above 15% indicates excessive particle size variation, which may lead to segregation during transport and feeding. Pellet quality is assessed by the Pellet Durability Index (PDI) or the modified Holmen test. A PDI above 80,85% is generally considered acceptable for most broiler diets, but the target should be based on the specific mill, feed ingredients, and bird age. The [Pelleting of broiler diets: An overview with emphasis on pellet quality and nutritional value](https://api.elsevier.com/content/abstract/scopus_id/84872875882) (2013) confirms that pelleting conditions,conditioning temperature, die thickness, and use of binders,all influence durability and, consequently, bird performance. On-farm monitoring of feed access is straightforward. At several points each day, the feeder should be checked for fines accumulation, bridging, or blockage. Birds should be observed during feeding to ensure they are eating readily and not wasting feed. A sudden decrease in feed intake often precedes a drop in water consumption or an increase in mortality. The [PubMed record 42061256](https://pubmed.ncbi.nlm.nih.gov/42061256/) correlates fine buildup in feeders with reduced feed intake and increased feed-to-gain ratio. ## Welfare, Worker Safety, and [Food Safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) Feed form affects broiler welfare through gut health and leg condition. A functioning gizzard maintained by coarse particles reduces the risk of proventricular dilatation and enteritis. The [PubMed record 41967320](https://pubmed.ncbi.nlm.nih.gov/41967320/) notes that birds fed finely ground mash have higher incidence of footpad lesions due to wet litter. Pellet quality also influences welfare, poorly bound pellets break into sharp fragments that can injure the oral cavity and esophagus. Regular observation of bird behavior and post-mortem examination of the gizzard and proventriculus should be part of routine health checks. Worker safety is impacted by dust generation from fine particles and feed handling. High dust levels can cause respiratory irritation and increase fire risk. Adequate ventilation in feed storage and milling areas is necessary. The [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) guidelines recommend dust masks and proper housekeeping to minimize respirable particulates. Food safety is a parallel concern. Mycotoxins, such as aflatoxins and deoxynivalenol, are more concentrated in fines because smaller particles have higher surface area and can become contaminated during milling and storage. Careful feed purchase specifications and regular mycotoxin testing of finished feed are prudent. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) provides frameworks for feed safety management along the production chain. ## Failure Patterns and Corrective Actions Several common failure patterns emerge when feed form and particle size are mismanaged. The first is excessive fines in the feeder, which often results from poor pellet durability, improper handling, or excessive augering. Corrective actions include reducing conveying speed, minimizing drop heights, and using pellets with higher durability. Another failure pattern is feed sorting by birds, especially in mash diets. This leads to uneven nutrient intake and increased feed wastage. The solution is to improve particle size uniformity or switch to a crumble or pellet form. A third pattern is gizzard erosion or poor gizzard development in birds fed predominantly pellets with very fine grind. This is observed as pale, flaccid gizzards at necropsy. The [Effects of oat hulls and wood shavings on digestion in broilers and layers fed diets based on whole or ground wheat](https://api.elsevier.com/content/abstract/scopus_id/0242488089) (2003) demonstrates that inclusion of insoluble fiber sources can mitigate this effect by slowing feed passage and maintaining gizzard activity. Finally, wet litter and high mortality due to enteric disease are associated with high fines and poor pellet quality. In such cases, producers should evaluate the particle size distribution of the feed delivered and the feeder management practices. Adjusting the grinding process,for example, using a roller mill instead of a hammer mill,can produce a coarser, more uniform particle size as described in [Physical and nutritional effects of pelleting of broiler chicken diets made from wheat ground to different coarsenesses by the use of roller mill and hammer mill](https://api.elsevier.com/content/abstract/scopus_id/7944234561) (2004). ## Professional Escalation If on-farm monitoring reveals persistent problems despite adjusting feed form or particle size, consultation with a poultry nutritionist or extension specialist is warranted. Complex interactions between feed form, ingredient quality, and bird health may require laboratory analysis of feed (e.g., PDI, mycotoxin profile, amino acid digestibility) and detailed necropsy data. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) provides resources for veterinarians and producers to report disease trends and obtain diagnostic support. When food safety is implicated, local veterinary authorities and feed regulatory agencies should be notified to prevent wider distribution of contaminated feed. ### Health Observation and Biosecurity Broiler health outcomes are directly influenced by feed particle size and form through effects on gastrointestinal development and microbial ecology. Feeding mash or coarsely ground particles promotes gizzard function and gizzard size, enhancing grinding activity and reflux of digesta. This physiological stimulation reduces the pH of the proventriculus and gizzard, creating a barrier to pathogenic bacteria. Conversely, finely ground feed or poorly formed pellets can lead to gizzard atrophy, increased intestinal pH, and higher susceptibility to enteric disorders such as [necrotic enteritis](/knowledge/bacteria/avian-bacteria/necrotic-enteritis-poultry) and coccidiosis. The influence of grinding and pelleting on microbial composition in the digestive tract has been documented, pelleting may reduce bacterial diversity but also can increase the risk of pathogen survival if pellet quality is poor and feed fines accumulate in the crop [The influence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens](https://api.elsevier.com/content/abstract/scopus_id/0036730317). Feeding whole or coarsely ground wheat, as opposed to finely ground wheat, has been associated with altered digesta viscosity and gut microbiota profiles [Effects of oat hulls and wood shavings on digestion in broilers and layers fed diets based on whole or ground wheat](https://api.elsevier.com/content/abstract/scopus_id/0242488089). For these reasons, feed form management is a component of herd health biosecurity. Biosecurity protocols at the feed mill and farm level should address feed access and contamination risks. If pellets crumble excessively, the resulting fines increase dust, which can facilitate aerosol transmission of pathogens such as [avian influenza](/knowledge/bacteria/avian-bacteria/avian-influenza-cdc-global-surveillance) viruses. The WOAH Terrestrial Animal Health Code provides guidance on preventing pathogen introduction through feed ingredients and equipment [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). Similarly, USDA APHIS recommends monitoring feed storage, cleaning feed lines regularly, and avoiding feed sources from areas with disease outbreaks [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease). Proper particle distribution reduces selective feeding, ensuring all birds consume balanced nutrients, which supports immune function and overall flock uniformity. ### Diagnostic and Veterinary Escalation Observation of flock behavior and production records is the first tier in identifying feed form problems. Reduced feed intake, increased water consumption, wet litter, poor growth uniformity, and elevated feed conversion ratio may indicate that pellet quality has declined or that particle size is inappropriate for the bird age. When these signs appear, the feed form should be quantified using standard sieve analysis and the pellet durability index measured. The Merck Veterinary Manual advises that changes in feed texture can be a confounding factor in disease diagnosis, a thorough feed evaluation should accompany any veterinary investigation [Merck Veterinary Manual](https://www.merckvetmanual.com/). Escalation to a veterinarian is warranted if intestinal health problems persist after feed form correction, as concurrent infections or management factors may be involved. Veterinary diagnostic procedures should include necropsy with evaluation of gizzard development, gut mucosal integrity, and presence of pathogens. Feed samples from the same lot should be retained for analysis. The USDA National Animal Health Monitoring System reports that feed-related disorders are often underdiagnosed because clinical signs are nonspecific [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms). Collaboration among nutritionist, farm manager, and veterinarian is necessary to differentiate between nutritional, infectious, and environmental causes of enteritis. Uncertainty remains regarding the optimal particle size for all production systems. The interaction of particle size with feed ingredients, processing method, bird genetics, and environmental stressors is complex. For example, wheat-based diets may respond differently to coarse grinding than corn-based diets. The review on feed particle size implications for poultry digestion emphasizes that mean particle size alone does not predict performance, the distribution of particles, especially the fraction of fines, is critical [Feed particle size: Implications on the digestion and performance of poultry](https://api.elsevier.com/content/abstract/scopus_id/34748888312). On-farm empirical testing under local conditions is recommended, with continuous monitoring of pellet quality and bird performance. ### Sustainability Feed form management contributes to sustainability by improving feed conversion efficiency, reducing feed waste, and lowering the carbon footprint of broiler production. Well-formed pellets minimize sorting and spillage, decrease dust emissions, and allow more precise nutrient delivery. Pelleting also reduces energy requirements for feed intake, as birds expend less effort eating pellets compared to mash. However, pelleting is energy-intensive at the mill. Balancing the energy invested in high-quality pellets against the gains in feed efficiency can optimize net environmental impact. The overview of pelleting effects on nutritional value notes that improving pellet quality often requires attention to ingredient selection and conditioning parameters [Pelleting of broiler diets: An overview with emphasis on pellet quality and nutritional value](https://api.elsevier.com/content/abstract/scopus_id/84872875882). Using coarser grind in the mash phase before pelleting can enhance pellet quality and also support gut health, a dual benefit. The FAO Animal Production and Health division encourages integrated approaches that align productivity with resource use efficiency [FAO Animal Production and Health](https://www.fao.org/animal-production/en/). ## Frequently Asked Questions **1. What is the best mean particle size for broiler starter mash?** No single value applies to all flocks. Research indicates mean particle size between 0.8 and 1.2 mm for corn-based starter diets supports gizzard development and reduces feed sorting, but on-farm testing remains necessary because ingredient characteristics vary. **2. How can I measure pellet quality on farm?** Use a pellet durability index tester or a simple sieve stack. Record percentage of fines passing through a 2 mm sieve. Fewer than 10% fines is a basic target for many operations, but this threshold should be validated for each feed formulation. **3. Does crumble form provide benefits over mash for young broilers?** Crumble is produced by crushing pellets, which can reduce fines compared to mash but may still create some dust. The main advantage is increased feed intake and ease of swallowing for chicks. However, hard crumbs that contain large fines can still cause gizzard hypoplasia if particle size is too fine. **4. How does particle size affect the risk of [necrotic enteritis](/knowledge/bacteria/avian-bacteria/poultry-necrotic-enteritis-pathogenesis-control)?** Coarse particles promote gizzard function and lower intestinal pH, which inhibits pathogenic Clostridium perfringens. Fine particles reduce gizzard activity and may increase intestinal pH, creating a favorable environment for pathogen proliferation. Feed form is a risk factor, not a sole cause. **5. What records should I keep for feed form management?** Keep batch records of pellet durability index, percentage fines, sieve distribution data, feed intake per pen, body weight uniformity, and mortality with necropsy findings. These data help identify changes before production suffers. **6. Can I mix different feed forms in the same feeding system?** Yes, but management becomes more complex. Birds may selectively consume pellets and leave fines, leading to nutrient segregation. If mixing, ensure the fines fraction does not increase beyond acceptable levels and that feeding lines are cleaned regularly. **7. How does ambient temperature affect the relationship between particle size and feed intake?** High temperatures reduce feed intake, and birds may prefer larger particles or pellets to minimize feeding time. However, if pellets are too hard, birds may decrease intake further. Adjusting particle size or adding fat can help maintain feed intake during heat stress. **8. Should I consult a veterinarian if I see wet litter and poor feathering?** Yes, especially if feed form changes have not resolved the problem. Wet litter can result from many causes, including gut infection, electrolyte imbalance, or mycotoxin contamination. A veterinarian can guide diagnostic testing to rule out infectious agents before altering feed form again. ### Educational Veterinary Notice Feed form and particle size are fundamental management tools that influence broiler health, performance, and sustainability. Regular monitoring of pellet quality, particle distribution, and flock production records allows early detection of problems. Collaboration among nutritionists, farm managers, and veterinarians is essential to interpret feed-related changes in the context of overall flock health. No single recommendation substitutes for on-farm observation and continuous improvement. When clinical signs such as mortality spikes, severe growth depression, or persistent enteritis arise, veterinary consultation is critical to identify underlying infectious or management factors that feed form alone cannot correct. ## Related Farming Guides - [Broiler Chicken Farming Flock Management From Placement To Processing](/knowledge/animal-farming/poultry/broiler-chicken-farming-flock-management-from-placement-to-processing) - [Layer Chicken Farming Pullet Development Egg Production Nutrition And Flock Health](/knowledge/animal-farming/poultry/layer-chicken-farming-pullet-development-egg-production-nutrition-and-flock-health) - [Broiler House Ventilation Fundamentals](/knowledge/animal-farming/poultry/broiler-house-ventilation-fundamentals) - [Poultry Farm Biosecurity Checklist](/knowledge/animal-farming/poultry/poultry-farm-biosecurity-checklist) - [Poultry Mortality Investigation And Flock Records](/knowledge/animal-farming/poultry/poultry-mortality-investigation-and-flock-records) ## Related Clinical & Scientific Guides * [Poultry Farm Fencing: Materials, Design, and Predator Exclusion](/knowledge/animal-farming/poultry/poultry-farm-fencing-materials-design-predator-exclusion) * [Broiler House Wind Speed and Airflow Measurement](/knowledge/animal-farming/poultry/broiler-house-wind-speed-airflow-measurement) * [Broiler House Heating Systems: Types and Efficiency](/knowledge/animal-farming/poultry/broiler-house-heating-systems-types-efficiency) ## References and Further Reading - [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) - [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) - [Merck Veterinary Manual](https://www.merckvetmanual.com/) - [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.