ISSUE FOCUS FEED & ADDITIVE MAGAZINE March 2023 41 Step 1: Calculate the CP in the supplement and grain mixtures. • Supplement mixture o 50% SBM × (54 ÷ 100) = 27% CP o 50% CGF × (24 ÷ 100) = 12% CP o 27% + 12% = 39% CP • Grain mixture o 60% Corn × (10 ÷ 100) = 6% CP o 40% SBH × (12 ÷ 100) = 4.8% CP o 6% + 4.8% = 10.8% CP Step 2: Place the CP for each mixture on the Pearson Square and subtract diagonally. • 39.0 – 15.0 = 24 parts grain mixture • 10.8 – 15.0 = 4.2 parts supplement mixture • 24 + 4.2 = 28.2 total parts • Grain mixture: (24 ÷ 28.2) × 100 = 85.1% • Supplement mixture: (4.2 ÷ 28.2) × 100 = 14.9% Step 3: Determine how much of each ingredient are needed. • Supplement mixture o 4.2 parts × 50% = 2.1 parts SBM and CGF each o (2.1 parts ÷ 28.2 parts) × 100 = 7.45% SBM and CGF each • Grain mixture o 24 parts × 60% = 14.4 parts Corn - (14.4 ÷ 28.2) × 100 = 51.06% Corn o 24 parts × 40% = 9.6 parts SBH - (9.6 ÷ 28.2) × 100 = 34.04% SBH Step 4: Check the math. • 7.45 lb × 54% CP = 4.02 • 7.45 lb × 24% CP = 1.79 • 51.06 lb × 10% CP = 5.11 • 34.04 lb × 12% CP = 4.08 • 4.02 + 1.79 + 5.11 + 4.08 = 15 lb CP Step 5: Convert to as-fed basis. CONCLUSION The Pearson Square is an excellent tool to use when formulating livestock rations. It is most efficient when only two ingredients are being fed. However, more ingredients can be used with a bit more math involved. The Pearson Square can be effective if access to diet formulation software is limited. A Pearson Square can often be used when mixing high- and low-quality forages together. Remember when using a Pearson Square, it’s important to work within the same units, such as dry matter or as-fed or pounds and kilograms. Any nutrient can be used to balance a diet with a Pearson Square as long as the nutrient requirement falls between the nutrient concentrations in the feeds used. Remember to always check your math when finished with a Pearson Square. About Dr. Megan Van Emon Dr. Megan Van Emon is an Extension Beef Cattle Specialist at Montana State University. Her research focuses on supplementation strategies, cow-calf production, water quality, and bull development. Dr. Van Emon’s research and extension programs focus on ruminant nutrition and improving beef cattle production in Montana and throughout the United States. She is located at USDA-ARS Fort Keogh in Miles City, Montana.
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