Blend two feeds to hit a target crude protein % with the Pearson square — and get pounds of each for a batch.
Use this when you mix a grain with a protein supplement (for example corn and soybean meal) and want the blend to land on one target nutrient, usually crude protein.
The target must sit between the two feeds. You cannot reach 20% protein by mixing a 9% feed with a 16% feed — the calculator will tell you when the target is out of range.
Draw a square with the target in the middle and the two feeds on the left corners. Subtract diagonally, ignoring signs: the difference between Feed B and the target is the parts of Feed A, and the difference between Feed A and the target is the parts of Feed B. Each feed's share is its parts divided by total parts.
parts_A = |B% − target%|
parts_B = |A% − target%|
share_A = parts_A ÷ (parts_A + parts_B)
lb_A = batch × share_A · lb_B = batch − lb_A
Corn at 9% CP, soybean meal at 44% CP, target 14% CP:
Parts corn = |44 − 14| = 30; parts soybean meal = |9 − 14| = 5; total = 35.
Corn share = 30 ÷ 35 = 85.71%; soybean meal = 5 ÷ 35 = 14.29%. A 1,000 lb batch needs about 857.1 lb corn and 142.9 lb soybean meal.
Check: (857.1 × 0.09 + 142.9 × 0.44) ÷ 1,000 = 14.0% CP.
Assumptions: exactly two feeds; nutrient values on the same basis (both as-fed or both dry matter).
Limits: balances one nutrient only. Energy, minerals, fiber, and intake limits are not checked. A third fixed ingredient needs a separate step.
Responsibility: use feed-test values and have production rations checked by a nutritionist or Extension specialist.
Yes. The square works for any single nutrient expressed as a percent or concentration, such as TDN, as long as both feeds and the target use the same basis.
Set the fixed ingredient aside, recalculate the target for the remaining pounds, then run the square on the two feeds that make up the rest.
Either, but do not mix bases. Converting both feeds to dry matter first gives the cleanest answer for wet feeds.