Balance a total mixed ration (TMR) for cattle by blending ingredients to meet crude protein and TDN targets. Free online TMR formulation tool.
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. It illustrates the fundamental trade-off between high-protein supplements and lower-protein forages that underlies all ration formulation. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation.
Feeding a balanced TMR maximizes feed efficiency, supports consistent animal performance, and prevents metabolic disorders. This calculator gives you a quick blend ratio for two ingredients so you can meet protein targets without expensive formulation software. It’s ideal for small operations and field estimates. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Pearson Square method: Parts of A = |CP_B − Target CP| Parts of B = |Target CP − CP_A| Total parts = Parts of A + Parts of B % Ingredient A = (Parts of A / Total parts) × 100 % Ingredient B = (Parts of B / Total parts) × 100 Blend TDN% = (%A × TDN_A + %B × TDN_B) / 100
Result: 83.3% Ingredient A, 16.7% Ingredient B
Parts of A = |44 − 14| = 30. Parts of B = |14 − 8| = 6. Total = 36. %A = 30/36 = 83.3%. %B = 6/36 = 16.7%. Blend TDN = (0.833 × 65) + (0.167 × 80) = 54.1 + 13.3 = 67.5% TDN. The ration meets the 14% CP target.
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.
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.
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.
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.
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.
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.
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.
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.
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.