There is no such thing as "poultry formulation" as a single category. A broiler in the growing phase, a commercial layer at peak lay, and a breeder hen have such distinct nutritional requirements that using the same formulation logic for all three is a sure source of underperformance. Brazilian poultry farming is today one of the most efficient sectors in the world at converting feed into animal protein, but that efficiency depends on progressively more precise formulations: digestible amino acids instead of crude protein, enzyme matrices declared in the formulation, managing the variability of soybean meal and corn between harvests, and a solid understanding of the physiological differences between categories. This guide covers the technical fundamentals that guide these decisions.
Broilers: production phases and phase-specific formulation logic
Modern broiler strains have the genetic potential to reach 2.6 to 2.8 kg live weight in 35 to 40 days with feed conversion close to 1.70, but this potential is only expressed when the diet sequence is correctly calibrated for each phase. Phase divisions are not arbitrary: they reflect real discontinuities in nutritional requirements as the bird grows.
In the pre-starter phase (days 1 to 7), the digestive tract is still developing and the capacity to digest complex ingredients is limited. Digestible lysine requirement is high relative to body weight, above 1.30% in the diet, and ingredients must have high digestibility and palatability. Use of corn gluten meal, concentrated or extruded soy protein, and highly soluble synthetic amino acid sources is justified at this phase for the impact on intake and early intestinal development.
In the starter (days 8 to 21) and grower (days 22 to 33) phases, the corn-soybean meal base takes center stage. The relationship between digestible amino acid concentration and diet metabolizable energy is the central parameter: when there is more energy relative to amino acids than the bird needs for protein deposition, excess energy is deposited as fat, worsening carcass yield without necessarily improving weight gain. Digestible lysine drops progressively from about 1.15% in the starter phase to about 0.90% in the grower phase, and formulation must follow this curve.
In the finisher phase (day 34 to slaughter), attention shifts to carcass yield and meat quality. Excess abdominal fat and reduced breast are signs of energy-protein imbalance at this phase. Adequate vitamin E levels (above 100 IU/kg of diet) in the pre-slaughter phase improve muscle oxidative stability after slaughter, reducing lipid oxidation and drip loss, parameters controlled in export contracts. Organic selenium has more efficient muscle deposition than sulfate and complements vitamin E antioxidant protection.
Digestible amino acids and ideal protein in poultry
Formulation based on total crude protein is technically imprecise because it does not capture the actual digestibility of the amino acids present in ingredients. Two soybean meals with 46% crude protein can have very different standardized ileal digestibility of lysine (SID) if one underwent excessive thermal processing. The Maillard reaction between free lysine and reducing sugars during overheating produces unavailable lysine compounds that pass through crude protein analysis undetected but that the animal cannot utilize.
Modern broiler formulation works with SID amino acids (standardized ileal digestibility), the most precise metric for what the animal actually absorbs in the small intestine. Lysine is the reference amino acid of the ideal protein concept, and other amino acids are expressed as proportions of it. The most used ratios for broilers in growing phases are: threonine around 67%, methionine alone around 38–40%, methionine plus cystine around 72%, tryptophan around 16–18%, valine around 77%, and isoleucine around 67%. These ratios vary between references (Rostagno, NRC, CVB) and between production phases, but provide a framework for detecting when a formula is deficient in a specific amino acid.
The main practical application of this concept is crude protein reduction with synthetic amino acid supplementation. Diets with 19–20% crude protein, adequate in digestible lysine, methionine, threonine, and tryptophan, have equivalent performance to diets with 21–22% crude protein formulated only with natural protein ingredients. Each percentage point of crude protein reduction while maintaining digestible amino acids reduces nitrogen excretion by approximately 8%, with direct environmental benefit and, depending on relative prices of synthetic lysine versus soybean meal, with diet cost reduction.
Energy system in poultry: ME, AMEn, and Rostagno equations
The energy system for poultry uses Apparent Metabolizable Energy corrected for nitrogen retention (AMEn) as the reference. Nitrogen correction is necessary because the animal's protein balance (protein retention or catabolism) affects the amount of nitrogenous energy excreted in urine, and ignoring this effect introduces error in ME values calculated by balance trials.
The Brazilian Tables for Poultry and Swine (Rostagno) provide equations for predicting AMEn from ingredient chemical composition, which allows recalculating the energy value of a specific lot when bromatological analysis is available. For broilers, equations for plant-origin ingredients are:
AMEbroilers = 4.31 × CPd + 9.29 × EEd + 4.14 × NFEd
AMElayers = 4.31 × CPd + 9.29 × EEd + 4.14 × NFEd + 0.3 × UNDFd
Where CPd, EEd, and NFEd represent respectively digestible crude protein, ether extract, and nitrogen-free extract for poultry, and UNDFd is the undigested nitrogen-free extract plus crude fiber. For animal-origin ingredients and pure fats, the fiber term is omitted from the equation. Inserting these equations into formulation software allows bromatological composition updates for a corn or soybean meal lot to automatically recalculate energy value, without the formulator needing to make this adjustment manually.
A relevant physiological aspect of the poultry energy system is that birds regulate voluntary feed intake predominantly by diet energy. When energy density increases, volumetric intake falls. This has two practical formulation implications: first, increasing diet energy without proportionally increasing amino acid concentration results in lower absolute daily amino acid intake, which can compromise performance even though diet percentages appear correct. Second, formulating based only on nutrient concentration (% in diet) without considering absolute daily intake is a recurrent error source in operations that vary diet energy levels.
Ambient temperature amplifies this effect. Broilers in environments above 30°C reduce intake to decrease metabolic heat production, reducing absolute intake of all nutrients. Formulating summer diets with higher digestible amino acid and energy concentrations to compensate for lower volumetric intake is a necessary practice on farms without adequate climate control in Brazilian tropical and subtropical regions.
Layers: the specificities requiring a completely different approach
Commercial layer formulation differs from broiler formulation in virtually all critical nutrients. Muscle growth ceases to be the dominant criterion and egg production with shell quality becomes the central axis of formulation.
Calcium: the highest requirement among production species
A layer producing 300 eggs per year deposits approximately 1.5 kg of calcium in shells alone over a laying cycle. Daily absorbable calcium requirement at peak production is between 4.0 and 4.5 g, representing a concentration of 3.5% to 4.0% total calcium in the diet at typical intake of 110 to 120 g/day. No other production species has a relative calcium requirement close to this magnitude.
But the most important — and frequently overlooked — aspect of calcium formulation for layers is the temporal pattern of consumption. Eggshell calcification occurs predominantly during the 16 to 20 hours after ovulation, which in the hen's natural physiology corresponds to the nighttime period. During this period, the bird mobilizes calcium from two sources: medullary bone (a calcium reservoir dynamic and specific to birds) and the calcium present in the digestive tract. Calcium availability in the tract during the night depends on the speed of feed passage through the gizzard: fine limestone (particles smaller than 1 mm) passes quickly and doesn't guarantee sustained nighttime supply, while coarse limestone (particles above 2 mm, or "oyster shell limestone") is retained in the gizzard for more hours and serves as a slow-release calcium reservoir during the calcification period.
Diets with exclusively fine limestone in layers in the second half of the laying cycle (birds over 60 weeks) frequently result in early shell quality decline and increased cracked eggs, even when total calcium level in formulation is correct. The recommended practice is to use a mixture of fine and coarse limestone, with increasing proportion of coarse limestone as the flock advances in age.
Phosphorus and vitamin D in layers
Available phosphorus requirement in layers is lower than in broilers (around 0.30% to 0.35%), but the Ca:P ratio must be carefully monitored. Excess calcium relative to available phosphorus compromises intestinal absorption of both and can contribute to osteoporosis in older birds, even with apparently adequate absolute phosphorus levels.
The form of vitamin D3 has growing relevance in laying poultry. 25-OH-cholecalciferol (calcifediol), a pre-activated form of vitamin D3, has superior bioavailability compared to conventional vitamin D3, especially in situations of compromised hepatic function (older birds or those with infectious challenges) or heat stress. In layers over 70 weeks or with a history of shell problems, replacing part of the premix vitamin D3 with 25-OH-D3 can have more consistent practical results than simply increasing the conventional D3 dose.
Amino acids in layers: requirement logic per egg
In layers, amino acid requirements are best expressed in grams per day rather than percentage of diet, because what matters is the absolute daily amino acid intake to sustain egg production, regardless of feed intake. Digestible lysine requirement for a high-performance layer is between 720 and 780 mg/day; digestible methionine between 380 and 420 mg/day.
This means that amino acid concentration in the diet must be adjusted according to expected intake. A layer in a 33°C environment consuming 105 g of feed per day requires a diet with higher digestible lysine concentration than the same bird in a 23°C environment consuming 120 g, so that absolute daily intake is equivalent. Ignoring this adjustment results in amino acid deficit in hot months, manifesting as a drop in lay rate, reduction in egg size, or loss of body score that compromises second-half-of-cycle performance.
Soybean meal quality: the ingredient with the greatest formulation impact
Soybean meal is the main protein source in poultry diets in Brazil and has greater compositional and qualitative variability than its position as a "standard ingredient" suggests. Two parameters determine the meal's quality from a nutritional standpoint: PDI (Protein Dispersibility Index) and the urease index.
PDI measures protein water solubility and serves as a thermal processing indicator. A very low PDI (below 15%) indicates overheating: protein has become less soluble and digestible amino acids, especially lysine, have been compromised by Maillard reactions. A very high PDI (above 35–40%) indicates under-processing: raw soybean antinutritional factors, especially trypsin inhibitors and lectins, were not sufficiently inactivated, reducing protein and starch digestibility and potentially causing pancreatic hypertrophy.
The urease activity index is the most used practical indicator in receiving control: it measures urease enzyme activity as a proxy for antinutritional factor inactivation. The target value is between 0.05 and 0.20 pH units variation in a 30-minute assay. Values above 0.20 indicate under-processing; below 0.05 with PDI below 10% indicates overheating.
For the formulator, a partially overheated meal lot means the total lysine declared in crude protein analysis does not reflect actual digestible lysine. Well-processed meal has SID lysine around 2.70–2.85%; overheated meal may have 2.40% or less, without this being detectable by routine crude protein analysis. When formulation uses the standard table value and the actual ingredient delivers less digestible lysine, flock performance deteriorates without an apparent cause in management or health.
Managing this variability requires systematic analysis at receiving, ideally with NIRS for rapid screening and analytical confirmation for lots with deviations. The flow of updating matrix values in formulation software from laboratory results closes the cycle between what was analyzed and what is formulated.
Phytase in poultry: matrix, temperature, and category particularities
Phytase use in poultry diets is now standard in commercial poultry, but correct declaration of its nutritional matrix in formulation remains an area of underutilization in many operations. Phytase releases phytate phosphorus from grains and oilseeds but also mobilizes calcium, zinc, manganese, and iron that were chelated to phytic acid, and improves amino acid and energy digestibility by reducing insoluble phytate-protein and phytate-starch complexes.
For broilers, typical credits of a 500 FTU/kg phytase include available phosphorus between 0.14 and 0.18 percentage points, calcium between 0.12 and 0.15 percentage points, digestible lysine between 0.04 and 0.06 percentage points, and metabolizable energy between 60 and 100 kcal/kg of diet. Declaring these credits in formulation software allows reducing dicalcium phosphate inclusion, which has relevant cost and represents the main vehicle for mineral phosphorus supplementation in poultry diets.
In layers, phytase calcium credit carries special weight given the high calcium level in the diet. By reducing part of the limestone supplementation via phytase credit, it is possible to slightly decrease the mineral load of the diet without compromising the calcium balance, which has a positive effect on palatability and mix uniformity.
A frequently overlooked point is phytase's thermal stability. Conventional phytases are inactivated above 65°C to 70°C during pelleting, which means that in operations that pellet with steam at 80°C to 90°C, part or all of the phytase activity is lost during processing. Heat-resistant (or "thermostable") phytases, developed through protein engineering to withstand higher conditioning temperatures, are needed in operations that pellet or use extrusion, ensuring that the declared activity is available in the finished product.
Exogenous enzymes for non-starch polysaccharides
Corn and soybean meal are ingredients with low soluble fiber content, making them easily digestible for poultry without needing specific enzymes beyond phytase. But when formulation includes wheat, barley, rye, triticale, or their by-products in relevant proportions, the situation changes completely.
These ingredients have high content of non-starch polysaccharides (NSPs), especially arabinoxylans (in wheat and rye) and beta-glucans (in barley). In poultry's small intestine, these polymers absorb water and increase intestinal content viscosity, reducing the rate of nutrient contact with the mucosa, compromising protein, starch, and lipid digestion, and favoring bacterial proliferation in the small intestine. The result is performance decline and frequently wet litter, causing litter and foot health problems in the poultry house.
Xylanase and beta-glucanase degrade these NSPs and eliminate or significantly reduce the viscosity effect. The response is more pronounced and predictable when the problematic ingredient is clearly identified and the enzyme is selected for the specific substrate. Combinations of xylanase, beta-glucanase, protease, and amylase have synergy when the diet includes multiple ingredients with different NSP fractions. Declaring the energy and protein matrix of these enzymes in formulation, when available on the product datasheet, allows capturing the economic credit they bring to the diet.
Intestinal health without growth promoters
Regulatory and market pressure for reduction or elimination of antibiotic growth promoters (AGPs) in poultry diets is a growing reality, especially for exporters serving European and North American markets. Removing AGPs without adequate nutritional and management substitution frequently results in flock uniformity deterioration, higher incidence of necrotic enteritis and coccidiosis, and worsened feed conversion.
The nutritional strategy for maintaining intestinal health without AGPs has multiple components. Organic acids (formic, fumaric, propionic, citric, and their salts) reduce gastric pH and exert direct bacteriostatic action. Gastric content acidification also improves endogenous protease activity and mineral solubility. Microencapsulated acid forms have more distributed action throughout the gastrointestinal tract, including the small intestine where bacterial pressure is most critical.
Coccidiostats, included as additives in formulation, are an inseparable part of sanitary management in litter-raised broilers. Their inclusion must be declared in formulation and comply with rotation programs established by the farm or integrator's sanitary protocol, considering withdrawal periods for slaughter and permitted drug categories.
Probiotics with Bacillus and Lactobacillus strains have growing evidence for improving intestinal mucosa integrity, modulating cecal microbiome, and reducing Salmonella and Campylobacter colonization. In AGP-free production systems, the combination of organic acids, phytase, NSP enzymes, coccidiostat program, and proven-quality probiotics constitutes the foundation of the nutritional approach for intestinal health.
Corn variability and mycotoxins: specific risks in poultry
Corn accounts for 60% to 70% of most broiler and layer diets. Its metabolizable energy variation between crops and regions can be 150 to 200 kcal/kg of diet, sufficient to measurably impact feed conversion. Starch, oil, and moisture content are the main determinants of this variation and must be monitored in each received lot.
Mycotoxins deserve special attention in poultry because birds have different sensitivity from swine for some major toxins. Aflatoxins B1, B2, G1, and G2 are especially problematic: birds are more sensitive than swine, with concentrations of 20 to 50 ppb already causing immune suppression, decreased laying, and liver changes in layers, and growth compromise in broilers. Fumonisins at high concentrations cause leukoencephalomalacia in horses, but in birds effects are more subtle: immune suppression, reduced cholesterol and fat-soluble vitamin absorption. Deoxynivalenol (DON) is the most prevalent in Brazilian wheat and causes feed refusal in birds above about 5 mg/kg, with direct impact on intake and performance.
Mycotoxin monitoring at corn and wheat receiving, combined with the decision to use adsorbents or direct contaminated lots to less sensitive species, is part of raw material quality control that feeds precision formulation.
Formulamix integrates Rostagno energy equations directly into ingredient matrices and connects with Labinfy to automatically recalculate energy and amino acid values with each newly analyzed lot, keeping formulation always based on the actual composition of ingredients in stock.
From formulation to productive result: cost per kg and cost per crate of eggs
The economic formulation assessment metric is not cost per ton of feed but cost per produced unit: cost per kg of live broiler in broilers, cost per crate of eggs in layers. A diet costing R$30/ton more that improves feed conversion from 1.78 to 1.72 in broilers can result in lower cost per kg produced, depending on selling price and farm scale. This calculation is rarely done systematically and is exactly where formulation software sensitivity analysis has direct application.
By varying digestible lysine level between 0.85% and 1.05% in 0.02% increments and mapping the corresponding formulation cost, the nutritionist visualizes the cost curve across a spectrum of options. Combined with historical feed conversion data by lysine level, obtained from literature or internal experiments, this analysis guides the decision on where to position formulation in the trade-off between feed cost and feed efficiency.
Frequent reformulations driven by ingredient price variation are a reality in integrated poultry. The ability to quickly respond to a soybean meal price increase, simulating partial substitution with canola, meat meal, or corn coproducts (gluten, DDG), and instantly checking the impact on digestible amino acid profile and cost, is what makes formulation software a strategic instrument in daily operations, not just a recipe calculator.