Poultry feed formulation — the Pearson square method
Want to know how much maize and how much soybean meal to blend so the feed contains 18% protein? The Pearson square is the simplest way — we explain it step by step, with a worked example and a verification check. At the end we are upfront about what this method does NOT calculate.
verifiedFrom the team that has organised work on poultry farms for years.
Poultry nutrition starts with protein. Protein (= the percentage of protein in the feed) is one of the most important parameters for chicken, turkey or broiler feed. Too little — the bird grows more slowly and lays less well. Too much — unnecessary cost. That is why farmers want to know how to blend ingredients to hit the target exactly. Below we show the simplest method. For ready-made feeding norms, see the guides on broiler feeding — norms or layer feeding — norms.
What is the Pearson square method?
The Pearson square (also called the "square method" or "cross method") is a simple technique for calculating in what proportions to blend TWO ingredients so that the mixture has a target protein percentage (or any other nutrient). It needs no computer or spreadsheet — just paper and a pen. The method has been used in animal nutrition science for decades. For more about feed mixtures in general, see the guide on poultry feed mixtures.
Important disclaimer — read before calculating
The Pearson square balances ONLY protein from two ingredients. A complete, real poultry feed must also have the right energy (megajoules or Mcal per kilogram), amino acids (lysine = the key amino acid for muscle building; methionine = an essential amino acid for layers), calcium, phosphorus, vitamins and a mineral premix. None of that is calculated by the square. A full feed recipe is produced with a dedicated feed balancing programme or by buying a ready-made feed from a mill. This guide is educational — it shows the method and teaches proportional thinking, but it does not replace a full feed balance. For commercial broiler and layer production it is always worth consulting a nutritionist.
How to calculate a feed recipe using the Pearson square
- 1
Draw a square and write the target protein in the centre
Draw a square — four lines forming a frame. In the centre write the target protein percentage for the finished feed. In our example: 18.
- 2
Write the ingredients on the left side of the square
On the left side of the square, at the top corner, write the first ingredient with its protein content. At the bottom corner write the second ingredient with its protein. In our example: top left = maize 9%, bottom left = soybean meal 44%.
- 3
Subtract diagonally — always the smaller from the larger
Now calculate diagonally. For each ingredient subtract the value on the opposite diagonal from the central target value — always take the absolute value (the result is always positive, never negative). Maize (top left): |44 − 18| = 26 parts. Soybean meal (bottom left): |18 − 9| = 9 parts. Write the results on the RIGHT side of the square — opposite the second ingredient (the diagonal result for maize = 26 is written next to the soybean meal, the diagonal result for soybean meal = 9 is written next to the maize — this is important, do not mix the sides).
- 4
Add up the parts and calculate percentage shares
Total: 26 + 9 = 35 parts. Share of maize: 26 ÷ 35 = 0.743 = 74.3%. Share of soybean meal: 9 ÷ 35 = 0.257 = 25.7%. This means: to make 100 kg of a blend with 18% protein, take about 74.3 kg of maize and about 25.7 kg of soybean meal.
- 5
Verify the result
It is always worth checking: 74.3% × 9% + 25.7% × 44% = 6.69% + 11.31% = 18.00% protein. Correct! If the result is off by tenths of a percent, that is a rounding difference, not an error in the method.
- 6
Important: this is only a protein balance
You have calculated the proportions that give 18% protein from these two ingredients. But a complete poultry feed needs much more: a vitamin and mineral premix, lysine, methionine, the right energy, calcium and phosphorus. If you are mixing feed on the farm, add a premix according to the manufacturer's recommendations and consult a nutritionist or a feed mill for the full recipe. Detailed norms for broilers are in the guide broiler feeding — norms, and for layers in layer feeding — norms. For more on broiler farming in general, see broiler farming.
Where the Pearson square is genuinely useful
Four situations where the square really helps.
Quick ratio estimates
You want a rough idea of how much soybean meal to combine with maize — without a computer programme. The square gives a result in a few minutes on paper.
Learning about feed balancing
This is a classic method taught on animal nutrition courses. If you are learning to think about ingredient proportions, the Pearson square is a good starting point.
Adjusting an existing blend
You have a ready blend and want to enrich it with one high-protein ingredient? The square shows in what ratio to add it to hit the protein target.
Checking a supplier's recipe
A feed supplier gives you the composition? You can check on paper whether the proportions of the two main ingredients add up — and ask informed questions.
What the Pearson square does NOT calculate
Honesty first — these things require a full feed balance or a specialist consultation.
Only two ingredients
The method works with a pair of ingredients. A real feed has several or more (maize, wheat, soybean meal, rapeseed meal, premix, lysine, methionine…). For three or more ingredients you need other methods or a computer programme.
Only crude protein
The square calculates crude protein percentage. It does not check the amino acid profile (lysine, methionine, threonine) — and poultry, especially broilers and layers, need these in specific proportions.
Energy is not calculated
Metabolisable energy (ME, megajoules per kg of feed) is the second key parameter alongside protein. The square ignores it. A feed can have good protein but poor energy — and the bird will not grow or lay as it should.
No calcium, phosphorus or vitamins
A layer needs a lot of calcium to build egg shells. Chicks and broilers must not receive too much phosphorus. A vitamin and mineral premix is part of every farm recipe. The square does not cover any of this.
Frequently asked questions about balancing protein in poultry feed
What is the Pearson square and what is it used for?add
The Pearson square is a simple method for calculating in what proportions to blend two ingredients so the mixture has a target protein (or other nutrient) percentage. You draw a square, write the target in the centre (e.g. 18% protein), write the two ingredients on the left with their protein contents, and subtract diagonally — always the smaller from the larger. The differences on the right are the number of parts of each ingredient. The method is useful for quick estimates but does not replace a full feed balance.
What protein percentage should broiler feed have, and what about layer feed?add
Broadly: broiler starter (the first weeks) needs about 22–23% protein, grower about 20%, finisher about 18%. A layer at peak production needs about 16–17% protein in the feed, but also a lot of calcium. Exact norms depend on the breed and producer — details are in the broiler feeding and layer feeding guides on DlaFerm.pl.
How much protein does maize have, and soybean meal?add
Maize typically has about 8–9% crude protein in dry matter — it is an energy ingredient, not particularly rich in protein. Soybean meal (a high-protein feed from soya, the product after oil extraction) has about 44–48% protein depending on the extraction level. That is why these two ingredients complement each other well: maize provides energy, soybean meal provides protein.
Can I balance three or more ingredients with the square method?add
The classic Pearson square only works with two ingredients. For three or more you use a system of equations or computer feed balancing programmes (e.g. spreadsheets with formulas or dedicated applications). In commercial farm practice, for larger scales it is worth consulting a nutritionist or feed mill for the recipe.
Is feed with 18% protein (maize + soybean meal) sufficient for poultry?add
Protein alone is not enough. Poultry feed must also have the right energy, amino acids (lysine and methionine in the right proportions), calcium, phosphorus and a vitamin and mineral premix. A blend of maize and soybean meal gives the right total protein, but without a premix, lysine and methionine the bird may grow more slowly or lay less well. In farm production a premix is always added according to the manufacturer's recommendations.
Where can I track flock nutrition in the DlaFerm.pl app?add
In DlaFerm.pl you can log feed consumption, bird weights and flock parameters. This lets you check whether the birds are growing to the norm and respond early to any deviations. Registration is free — write to us or create a farm account. Full support for feed modules requires contact with our team.
Track flock nutrition in DlaFerm.pl
Want feed consumption, weights and flock parameters in one place? Write to us or create a free farm account.
Phone
+48 796 258 151