Raw feed ingredients – grains, oilseeds, legumes, and by-products – are rarely ready to feed to poultry straight off the shelf. They may contain anti-nutritional factors (ANFs) such as trypsin inhibitors, phytates, and non-starch polysaccharides (NSPs) that block nutrient absorption, reduce digestibility, or even harm bird health. Feed processing is the set of physical and thermal techniques that convert these raw materials into safe, palatable, and nutritionally optimized feed. The methods used fall into two broad categories – cold processing, which works at or near room temperature, and hot processing, which uses heat, steam, and pressure to achieve more profound changes in feed composition and structure.
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Why feed processing matters for poultry
Feed processing refers to any treatment that animal feed undergoes prior to ingestion. In practical terms, it is what separates a nutritionally inert raw ingredient from a compound feed that delivers measurable growth performance. Feed accounts for 60-70% of total broiler production costs, so even modest improvements in nutrient utilization through processing translate directly into economic gains. Beyond cost efficiency, processing improves feed safety by destroying pathogens, reduces wastage during handling and feeding, and ensures birds receive a consistently balanced diet at every meal.
Anti-nutritional factors like protease inhibitors can inhibit proteolytic enzymes, reduce amino acid digestibility, and trigger pancreatic hypertrophy in poultry – a serious welfare and productivity concern. Proper processing neutralizes or removes these compounds before the feed ever reaches the bird. The standard operations in a feed manufacturing plant include receiving raw materials, grinding, proportioning, mixing, thermal treatment or pellet shaping, packaging, and warehousing.
Cold processing methods
Cold processing covers all techniques performed at or close to ambient temperature. These methods are energy-efficient, preserve heat-sensitive nutrients like vitamins and enzymes, and serve as the essential preparatory steps before any thermal treatment is applied.
Grinding
Grinding is the first physical transformation a raw ingredient undergoes. Raw ingredients are ground to a uniform particle size using hammer mills or roller mills, which increases surface area for better mixing and digestibility. Finer particle size means digestive enzymes in the bird’s gut can act on a greater surface of the feed substrate, improving nutrient release. However, excessive fineness produces dusty meals that birds find unpalatable and that increase respiratory irritation during feeding. The right particle size is therefore a balance – fine enough to improve digestibility, coarse enough to maintain palatability and gizzard health.
Mixing
Once ingredients are ground, they must be combined uniformly. Thorough mixing ensures that vitamins, minerals, amino acid supplements, and other additives are evenly distributed throughout the batch. Uneven mixing means some birds receive nutrient-deficient feed while others get an overdose of a particular additive – both outcomes are harmful. Modern feed mills use horizontal or vertical ribbon mixers with precisely timed mixing cycles to achieve consistent nutrient distribution across every kilogram of the final product.
Reconstitution
Reconstitution involves adding controlled amounts of moisture to dry grain before processing. This technique is especially useful for corn and other cereals, softening the kernel structure to reduce the energy demand of subsequent grinding and improving the uniformity of particle size. The added moisture initiates early hydration of starch granules, which slightly improves starch accessibility. Reconstitution is a low-cost method that enhances the efficiency of downstream processing steps without requiring heat or specialized equipment.
Soaking
Soaking is particularly valuable when legumes such as soybeans form part of the feed formulation. Soaking, germination, and fermentation using phytase enzymes or microorganisms can degrade up to 90% of the phytic acid in grains, legumes, and oilseeds. Beyond phytate reduction, soaking legumes begins the breakdown of trypsin inhibitors and reduces tannin content in sorghum and other grains. A study found that soaking feed for 12-24 hours increased dry matter digestibility in broilers aged 25-40 days compared to birds consuming dry mash feed. The method requires minimal equipment and is practical for small and medium-scale operations, making it a cost-effective strategy for improving feed quality without thermal inputs.
Hot processing methods
Hot processing uses heat, moisture, steam, and mechanical pressure to achieve structural and chemical changes in feed ingredients that cold methods cannot. These techniques improve starch gelatinization, denature proteins, destroy pathogens, and eliminate ANFs more comprehensively. The trade-off is higher energy consumption and equipment investment, but the returns in feed performance typically justify the cost.
Pelleting
Pelleting is the most prevalent heat treatment in poultry feed production. Its objective is to agglomerate smaller feed particles into larger, denser pellets that enhance feed intake, growth performance, and feed efficiency. The process begins with steam conditioning.
Hot conditioning is a fundamental step in preparing feed ingredients for pelleting. Steam conditioning enhances moisture content of the mash, which is necessary to form pellets that can withstand the rigors of transportation and storage. The conditioned mash is then forced through a die under pressure, forming uniform, dense pellets. By combining moisture, heat, and pressure on feed ingredients, a degree of starch gelatinization is produced which allows poultry to better utilize the nutrients in these ingredients, improving feed conversion.
Pelleting transforms soft, dusty feed into a hard pellet through compression, extrusion, and adhesion. The moisture from steam provides lubrication for compression and, in the presence of heat, causes some gelatinization of raw starch, resulting in adhesion. The resulting pellet form offers several practical advantages: pelleted feeds increase bulk density by 30-40%, allow more feed to be stored in the same space, and reduce ingredient segregation during handling. From a bird management perspective, most animals, when given the choice between the same feed in pellet or mash form, prefer pellets.
After pelleting, feed exits the die at high temperature and moisture content. Cold conditioning at this stage manages moisture levels, typically reducing them to a safe range of 12-14%, ensuring pellets maintain their quality and nutritional value during storage. If excess moisture is left unchecked, it can lead to mould growth, spoilage, and nutrient degradation. Cooled pellets are then screened to remove fines, which are recycled back into the process. For young chicks, a crumbler is used to reduce pellet size to a form that starter birds can easily consume.
One area of concern with pelleting is its effect on heat-sensitive feed additives. The pelleting process remains a potentially aggressive process on the stability of exogenous feed enzymes and vitamins – a major concern for feed manufacturers. Vitamins A, D, and some B-group vitamins are particularly susceptible to thermal degradation, so manufacturers often use overages or heat-stabilized premixes to compensate.
Extrusion
Extrusion processing operates on three principles: steam conditioning, high-temperature cooking, and high shear pressure. The process starts by formulating and tempering the mixture to about 30% moisture content. The extruder then subjects the feed to temperatures of 120-180°C under intense mechanical shear as it passes through the barrel. Upon exiting through a shaped die, the feed expands rapidly as internal pressure is released, creating a light, porous texture.
Extrusion is a high-temperature, short-duration process that combines heat and mass transfer, mixing, shearing, particle size reduction, melting, texturizing, and moulding. It is also a highly effective method to inactivate amylase inhibitors and trypsin inhibitors without altering protein levels. Extrusion combines moisture, high temperature, and pressure to modify starch and protein, enhancing their digestibility. There has been better performance in poultry fed extruded pellets than those fed mash. The downside is that the process is energy-intensive and capital-heavy, making it most appropriate for specialty feeds, aquafeed, or situations involving particularly problematic raw materials.
Roasting
Roasting is a dry heat treatment applied directly to whole grains or seeds. The roasting process breaks down the cellular structure inside the grain, increases its digestibility, and makes nutrients readily available for absorption. It is particularly effective for soybeans and cereals such as corn and barley.
For soybeans, roasting destroys trypsin inhibitors and urease activity – two of the most important ANFs affecting poultry – while preserving the protein content of the meal. Roasting soybeans kills mould and other contaminants and makes the beans easier to digest. It ties up the protein in the fiber of the soybeans and allows that protein to be absorbed by the animal, increasing feed value.
For cereal grains, the thermal effect gelatinizes starch within the kernel. Roasting ruptures the walls of starch cells, making the starch water-soluble – a process called gelatinization – which makes it more susceptible to amylase and increases feed efficiency. Research studies show that roasted corn is more digestible than raw corn, with digestibility increased by approximately 13%. Flame roasting can also effectively remove mould spores and reduce toxin levels that are harmful to poultry. Roasting is relatively inexpensive compared to extrusion and can be implemented at small and medium farm scales, making it a practical option where more capital-intensive equipment is unavailable.
Choosing the right processing method
No single processing method suits every situation. The choice depends on the type of feed ingredient, the class of bird being fed, available infrastructure, and cost constraints. Feed processing further adds to the cost of feed, and the cost of each strategy must be carefully weighed against achievable performance improvements and negative effects in the target animal.
Starter feeds for chicks generally benefit most from pelleting or extrusion because improved nutrient digestibility has a disproportionately large impact during the critical early growth phase. Grower and finisher diets may perform adequately as mash if cost control is the priority, though pelleted feeds still deliver measurable improvements. Techniques such as heat treatment, grinding, chemical treatment, soaking, and fermentation have been employed with varying degrees of success depending on the substrate, which underscores the importance of matching the processing method to the specific ingredient and the specific nutritional challenge being addressed.
Cold processing methods – grinding, mixing, reconstitution, and soaking – form the essential foundation of any feed manufacturing process. They are cost-effective, preserve heat-sensitive nutrients, and significantly reduce ANF content in legume-based diets. Hot processing methods – pelleting, extrusion, and roasting – go further by transforming the physical structure of feed, gelatinizing starch, denaturing proteins, and eliminating pathogens. Used in combination, these techniques produce feed that is safe, palatable, nutritionally dense, and suited to the specific needs of birds at different stages of production.
What do you think? Given that pelleting improves feed conversion but can degrade heat-sensitive vitamins, how should a poultry farmer balance processing intensity with nutrient preservation? And for small-scale producers with limited capital, which cold processing technique do you think offers the greatest nutritional benefit for the investment?
References
- https://poultry.extension.org/articles/feeds-and-feeding-of-poultry/anti-nutritional-factors-in-poultry-feed/
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/feed-processing
- https://poultry.caes.uga.edu/extension/poultry-nutrition/soybeans/antinutritional-factors.html
- https://dev.soyexcellence.org/interest-groups/feed-manufacturing-technology/forum/discussion/process-of-poultry-feed-pelleting/
- https://justagric.com/anti-nutritional-factors-in-animal/
- https://www.mdpi.com/2077-0472/15/5/476
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/pelletizing
- https://devenish.com/media/articles/the-essential-role-of-hot-and-cold-conditioning-in-feed-processing
- https://en.engormix.com/feed-machinery/feed-pelletizing/the-pelleting-process_a35607/
- https://www.nature.com/articles/s41598-023-36072-w
- https://www.pelletfeed.com/resources/the-process-of-feed-making.html
- https://pmc.ncbi.nlm.nih.gov/articles/PMC12024329/
- https://www.mecmargroup.com/en/news/benefits_of_grain_roasting_why_is_it_important-64
- https://roastamatic.com/blog/benefits-of-grain-roasting-your-feed/
- https://nutriroast.com/application-in-animals-feeds/
- https://roastamatic.com/blog/what-is-the-purpose-of-grain-roasting/
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