Feed formulation starts long before optimization software is opened. It starts when the nutritionist decides which ingredients will compose the formula database and what role each one will play in the diet. This decision is informed by a functional classification structure that organizes ingredients by their primary nutritional contribution: source of energy, protein, fiber, minerals, vitamins, or specific physiological effect. Knowing this structure in depth is what allows formulators to build balanced diets, manage ingredient variability, and make substitution decisions with technical and economic confidence.
This article covers the five major ingredient categories used in feed formulation for production animals, focusing on the main representatives of each group, the characteristics that define their nutritional contribution, and the critical points that make a difference in practical use.
Category 1: Roughages and forages
Roughages are characterized by high neutral detergent fiber (NDF) content and low energy density relative to the volume they occupy in the diet. They are the dietary base of ruminants and play a structural role in these animals' diets, going far beyond a simple nutrient source: they support rumen function, stimulate rumination, and maintain the fermentative environment that enables digestion of the entire diet.
The main roughages used in Brazilian animal production are tropical pastures (Brachiaria, Panicum, Cynodon), corn and sorghum silages, sugarcane, sugarcane bagasse, coast-cross and tifton hays, and grasses provided in troughs. Each has a very distinct quality profile in terms of NDF digestibility, crude protein level, net energy, and density, which directly influences the amount of concentrate needed to complement the diet and meet the animal's requirements.
Good-quality corn silage can have NDF digestibility above 55% and net maintenance energy above 1.55 Mcal/kg of dry matter, making it a premium roughage that supports high production levels when properly combined with protein concentrates. Poorly fermented silage, with high pH, high butyrate level, or mold, not only has reduced energy value but also compromises voluntary intake and ruminal health of animals that consume it. Silage variability between silos and along the feed-out face is one of the most challenging factors to manage in cattle diet formulation, and regular monitoring with bromatological analysis is essential for precise formulation.
For production systems that combine roughages with concentrates, such as feedlot cattle and intensive milk production, the interaction between effective fiber and concentrate is the parameter that defines ruminal health and production efficiency. Diets with effective fiber below the required minimum, resulting from roughages with poor physical quality or excessive concentrate proportion, predispose animals to subclinical ruminal acidosis, with performance consequences that often take months to be noticed and correctly attributed to nutritional origin.
Formulation watchpoint
Roughage composition is among the most variable across all ingredient categories. Moisture, cutting stage, forage species, fertilization, ensiling process, and climate conditions greatly affect delivered nutritional value. Working with fixed table values for silages and forages is one of the most frequent causes of formulation errors in ruminant diets. Regular NIRS or wet chemistry analysis and matrix updates based on real results are non-negotiable practices for rigorous formulation.
Category 2: Energy concentrates
Energy concentrates are ingredients with high levels of digestible carbohydrates, lipids, or both, low fiber content, and high energy density. They are the main source of metabolizable energy for monogastrics and fermentable energy for ruminants, and represent the largest fraction by weight in most commercial feeds for poultry, swine, and feedlot cattle.
Corn is by far the most relevant energy concentrate in Brazil, accounting for 60 to 70% of the typical formula in broiler and swine feeds. Its metabolizable energy for poultry is around 3,350 to 3,400 kcal/kg as-fed, with relevant variation depending on moisture level, grain size, and crop season. Besides corn, other frequently used energy concentrates include grain sorghum, wheat and its by-products (wheat bran, middlings, wheat flour), cassava (whole root or cassava meal), pelleted citrus pulp, and distillers grains (DDGS), as well as oils and fats.
Oils and fats are an energy subcategory with unique characteristics: they have metabolizable energy far higher than cereals (typically between 7,000 and 8,500 kcal/kg for poultry, depending on fatty-acid profile and quality), reduce meal feed friability, and improve palatability. Soybean oil is the most used in Brazil for poultry and swine, followed by poultry fat and beef tallow. Oil and fat quality is highly variable and directly affects energy value: high acidity and peroxide indexes indicate oxidation, which reduces fatty-acid digestibility and increases consumption of available vitamin E, besides potentially damaging the intestinal epithelium.
Formulation watchpoint
Corn moisture and the oxidative quality of oils and fats are the parameters that most often cause metabolizable-energy deviations relative to matrix values. For corn, each percentage point of moisture above 14% represents a proportional reduction in energy contribution per kilogram of feed. For oils and fats, determining acidity and peroxide index upon receipt is the minimum required to avoid incorporating a degraded ingredient that will compromise the energy efficiency of the entire formula.
Category 3: Plant protein concentrates
Plant protein concentrates are ingredients with crude protein levels generally above 20%, obtained mainly from processing oilseeds such as soybean, canola, sunflower, cottonseed, and peanut, as well as fermentation by-products such as sugarcane and brewer's yeasts. They are the main protein source in most monogastric feeds in Brazil and play an important role as a source of rumen-degradable protein in cattle diets.
Soybean meal is the global reference plant protein concentrate for monogastrics, with crude protein typically between 44% and 48% as-fed, a reasonably balanced amino-acid profile, and high digestibility when properly processed. Availability of lysine, the first limiting amino acid in corn-based diets for poultry and swine, is one of the best among plant meals, which is why the corn-soy pair has been the basis of Brazilian commercial feeds for these species for decades.
Other plant protein concentrates with growing use are canola meal, with an interesting sulfur amino-acid profile (methionine and cystine), sunflower meal, rich in protein but with high NDF that limits inclusion in monogastrics, potato protein concentrate from foam, and pea and other legume proteins, which have gained space mainly in aquaculture and premium pet food formulations as alternatives to animal protein.
Dehydrated yeasts, whether from sugarcane or brewing, are protein ingredients with distinct characteristics: besides protein (generally between 35% and 45% crude protein), they provide nucleotides, cell-wall mannan-oligosaccharides with prebiotic properties, and beta-glucans with documented immunomodulatory effects in poultry and swine. Their amino-acid digestibility is modest compared to soybean meal, but the combination of protein with bioactive compounds makes them dual-function ingredients with value that goes beyond direct nutritional contribution.
Formulation watchpoint
Thermal processing is the factor with the greatest impact on soybean-meal quality and deserves special attention. The urease index (to verify proper inactivation of trypsin inhibitors) and PDI (Protein Dispersibility Index, to detect overprocessing) are the two reference indicators to assess processing quality. A meal with high urease activity (above 0.2 pH variation) has active trypsin inhibitors that reduce protein digestibility. A meal with very low PDI (below 15%) underwent excessive temperature that damaged reactive lysine. Neither problem is detectable by conventional crude-protein analysis.
Category 4: Animal protein concentrates
Animal-origin meals and protein concentrates are obtained from processing by-products of the meatpacking, fishing, and dairy industries. They include meat and bone meal, poultry meal, fish meal, blood meal, spray-dried blood plasma, hydrolyzed feather meal, and milk protein concentrates and isolates (whey, casein). As a category, they combine high protein content with amino-acid profiles that often complement plant proteins, and are important sources of limiting amino acids such as lysine, methionine, cystine, and tryptophan.
Fish meal holds a unique position among animal protein concentrates due to the combination of high digestibility (generally above 85% for major amino acids), balanced amino-acid profile, high content of long-chain omega-3 fatty acids (EPA and DHA), and the presence of unidentified growth factors that have historically been associated with improved performance in piglets and broilers, besides being indispensable in diets for carnivorous aquaculture species. Its use in poultry and swine feeds in Brazil has decreased due to cost and availability, but it remains a reference ingredient in high-performance diets and in formulations for critical phases such as broiler pre-starter and swine nursery.
Meat and bone meal and poultry meal are the most widely used animal protein concentrates by volume in Brazil, especially in broiler and layer feeds. Quality variability of these ingredients is high: crude protein may vary from 35% to 65% depending on bone proportion (which contributes ash but not digestible protein), and amino-acid digestibility varies according to cooking process, temperature used, and material origin. Blood meal has the highest protein level among animal meals (above 80% crude protein), but variable amino-acid digestibility and limited palatability restrict its inclusion.
Spray-dried blood plasma is a high-value ingredient in nursery piglet diets. The combination of immunoglobulins, highly digestible albumin, and growth factors present in plasma contributes to intestinal integrity and immunity in newly weaned piglets at a time of high digestive-system vulnerability. Its cost is high, but the return in performance and reduced post-weaning mortality justifies inclusion in high-performance nutritional programs.
Formulation watchpoint
Quality variability in animal-origin meals is among the highest of all ingredients. High ash indicates excess bone material or addition of dried blood to artificially raise protein content. Lipid oxidation (assessed by TBA or peroxide index) compromises not only energy value but also protein digestibility and the animal's antioxidant status. Moisture above 10% predisposes to microbiological deterioration. Analytical monitoring at receipt of each batch, including protein, ash, moisture, ether extract, and oxidation indicators, is the only way to ensure that the ingredient entering the formula matches the matrix value used in calculation.
Category 5: Supplements, premixes, and additives
The fifth category groups ingredients that, in terms of inclusion volume, represent a small fraction of feed but have a disproportionately large nutritional and physiological impact. It includes mineral and vitamin supplements, premixes combining multiple micronutrients in a single source, and additives with specific technological or physiological functions.
Mineral supplements
The macrominerals most commonly supplemented in feed are calcium (via calcitic limestone or calcitic + aragonitic limestone for layers), available phosphorus (via dicalcium or monocalcium phosphate), sodium and chlorine (via sodium chloride), and in specific situations, magnesium and sulfur. The choice between calcium and phosphorus sources directly affects the available Ca:P ratio in the diet, which is critical both for bone mineralization and eggshell quality in laying hens.
Microminerals are included via trace premix, which usually combines zinc, manganese, copper, iron, iodine, selenium, and cobalt in forms and proportions suitable for each species and phase. The choice between inorganic forms (sulfates, oxides) and organic forms (chelates, complexes with amino acids or hydrolyzed proteins) has implications for bioavailability, environmental excretion, and cost, discussed in detail in animal nutrition fundamentals.
Vitamin premixes
Vitamin premixes provide fat-soluble vitamins (A, D3, E, K3) and water-soluble B-complex vitamins (B1, B2, B3, B5, B6, B7, B9, B12) that are not present in sufficient quantity in natural diet ingredients to meet the requirements of high-performance production animals. Vitamin premix formulation must consider thermal degradation losses during pelleting or extrusion, expected feed storage time, and the chemical forms used, which differ in stability and bioavailability.
Exogenous enzymes
Exogenous enzymes are the additives with the greatest impact on formulation cost in recent decades. The most used in monogastric feeds are phytase, xylanase, beta-glucanase, amylase, and protease, often combined in multienzyme preparations. Phytase has already been mentioned for its role in releasing phytate phosphorus, but its impact goes beyond phosphorus: it also improves digestibility of amino acids, calcium, and energy by destabilizing the phytate complex that sequesters these nutrients. Xylanases and beta-glucanases act on non-starch polysaccharides (NSPs) in the cell wall of cereals such as wheat, barley, and rye, reducing intestinal viscosity and improving digestibility of all dietary nutrients. For formulators, each enzyme has its own nutritional matrix that must be incorporated into formulation software so digestibility gains are captured in formula calculation and do not become only an additional cost without compensatory reduction in other ingredients.
Probiotics, prebiotics, and acidifiers
The group of additives focused on intestinal health has gained increasing relevance with restrictions on prophylactic antibiotic use in animal production. Probiotics, which are living microorganisms that benefit the host microbiota, prebiotics such as mannan-oligosaccharides (MOS) and fructo-oligosaccharides (FOS) that selectively feed beneficial microorganisms, and organic acidifiers such as formic acid, propionic acid, and acid blends that reduce pH in the upper digestive tract in swine and poultry, form a set of tools that allows the nutritionist to work on intestinal health without relying on growth-promoting antibiotics. These ingredients do not have nutritional matrices in the conventional sense, but they affect performance and must be evaluated through specific performance trials for each product and production system.
Antioxidants and preservatives
Antioxidants such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), ethoxyquin, and natural tocopherol blends have the technological function of preserving feed fat quality during storage, preventing lipid oxidation that reduces energy value and generates toxic byproducts. In feeds with high oil and fat content, or intended for markets requiring long shelf life, antioxidant selection and inclusion level are relevant technical decisions affecting both nutritional quality and product regulatory compliance.
Why functional ingredient classification matters in formulation practice
Understanding which category each ingredient belongs to and its primary function in the diet is what allows formulators to reason about substitutions on a technically grounded basis. When soybean meal prices rise sharply, the decision about which ingredient to use to compensate for reduced inclusion is not arbitrary: it is a decision about which other plant or animal protein sources can cover the digestible amino-acid profile being removed, at what cost, and with what implications for quality control and processing.
Likewise, when corn from a harvest arrives with lower-than-expected energy composition, the formulator who understands the logic of energy concentrates knows they can compensate by adjusting inclusion level of oil or an alternative energy byproduct, but also knows this substitution has implications for diet density, palatability, pellet consistency, and other parameters that must be verified.
This ability to reason about ingredients by category and function, not just as entries in a composition table, is what makes a nutritionist truly efficient. And this, combined with reliable and updated analytical data for each available real ingredient, allows formulation software to deliver not only the lowest-cost formula, but the lowest-cost formula that will work in practice.
Formulamix was developed to work with ingredients from all these categories, with configurable nutritional matrices that integrate laboratory analytical data and allow formulators to capture the real value of each available ingredient in lowest-cost formulation.