Total Mixed Ration Calculator

About the Total Mixed Ration Calculator

The Total Mixed Ration (TMR) Calculator helps you balance a two-ingredient ration to meet target crude protein (CP%) and total digestible nutrient (TDN%) levels for cattle. TMR feeding ensures every bite an animal takes contains a consistent blend of forages, grains, and supplements, eliminating sorting behavior and improving feed efficiency.

Balancing a TMR requires knowing the nutrient content of each ingredient and the target nutrient levels for the class of cattle being fed. This simplified calculator uses a Pearson Square approach for two ingredients to determine the proportion of each that achieves your CP target. It also reports the resulting TDN of the blend.

While commercial feedlots and dairies use sophisticated formulation software with dozens of nutrients and constraints, the two-ingredient Pearson Square remains a valuable teaching tool and quick field check. This page uses that method as a fast protein-target check, which is useful for field estimates even when full ration software does the final formulation.

When This Page Helps

Small operations often need a fast blend ratio before paying for a full reformulation. This page gives that rough mix while keeping the protein target in view.

How to Use the Inputs

1. Enter the crude protein (CP%) of Ingredient A (e.g., corn silage at 8%).
2. Enter the TDN% of Ingredient A.
3. Enter the crude protein (CP%) of Ingredient B (e.g., soybean meal at 44%).
4. Enter the TDN% of Ingredient B.
5. Enter your target CP% for the ration.
6. Review the blend percentages and resulting TDN of the mix.

Example Calculation

Tips & Best Practices

• The Pearson Square only works when one ingredient is above the target and one is below.
• For more than two ingredients, use linear programming software or consult a nutritionist.
• Always verify mineral and vitamin levels separately — the Pearson Square only addresses CP.
• Test your ingredients with a forage lab before formulating — book values can be inaccurate.
• Adjust the ration when switching to a new lot of hay or silage with different quality.
• TMR mixing order matters — add dry ingredients first, then wet ingredients for consistent blending.

TMR Feeding vs Component Feeding

TMR feeding delivers all nutrients in every bite, preventing cows from sorting and selectively eating grain while refusing forage. This improves rumen pH stability, reduces metabolic disorders like acidosis, and increases overall feed efficiency. Component feeding — offering forage and grain separately — allows sorting and creates inconsistent nutrient intake throughout the day.

Getting the Most From Your TMR

Proper mixing is as important as proper formulation. Over-mixing breaks down effective fiber length, while under-mixing leaves hot spots of grain or supplements. Target 3-5 minutes of mixing after the last ingredient is added. Use the Penn State Particle Separator to check particle size distribution.

When to Reformulate

Reformulate your TMR whenever you open a new lot of hay or silage, when forage test results change, when animal performance drops unexpectedly, or when ingredient prices shift significantly. Regular forage testing and ration adjustment keep your feeding program on track.

Frequently Asked Questions

• What is a total mixed ration?

  A TMR is a feeding method where all forages, grains, protein supplements, minerals, and vitamins are blended together into a single uniform mixture. Each bite contains the same nutrient balance, which improves intake consistency and rumen function.

• What is the Pearson Square?

  The Pearson Square is a simple algebraic method for determining the proportions of two ingredients needed to achieve a target nutrient level. It works by calculating the difference between each ingredient’s nutrient content and the target.

• Can I balance for more than two nutrients?

  The Pearson Square balances for one nutrient at a time with two ingredients. For multi-nutrient, multi-ingredient rations, use ration balancing software such as AMTS, NDS, or PC Dairy. These tools handle all nutrients and constraints simultaneously.

• What CP% target should I use for beef cattle?

  Growing calves need 12-14% CP. Finishing cattle need 12-13% CP. Lactating beef cows need 10-12% CP. Dry cows in mid-gestation need 7-8% CP. Consult NRC requirements for your specific class and production level.

• What is TDN?

  Total Digestible Nutrients (TDN) is a measure of feed energy calculated as the sum of digestible crude protein, digestible crude fiber, digestible nitrogen-free extract, and 2.25 times digestible ether extract. Higher TDN means more energy per pound of feed.

• How accurate is a two-ingredient ration?

  A two-ingredient ration can meet CP targets accurately but may not meet all mineral, vitamin, and fiber requirements. In practice, most rations contain 4-8 ingredients plus a mineral and vitamin premix to meet all nutritional needs.