YielixUnderstanding Dry Matter and Feed Rations
Compare feed on the material, not its water
Dry matter (DM) is the portion of feed remaining after moisture is excluded. Reporting ingredient quantity and nutrients on a DM basis lets a high-moisture feed and a dry feed be compared without letting water distort the result.
A feed test should state whether values are as-fed or dry-matter based. Use as-fed quantities to load and deliver feed, then use DM quantities to compare ingredients and calculate weighted nutrient contributions.
Convert as-fed ingredients to dry matter and inspect ration nutrient totals
Feed Ration Builder
Build feed rations with multiple ingredients and see nutrient totals on a dry-matter basis with CP, TDN, and NDF breakdown.
Read the basis before building a ration
Forage analysis is the best input for a ration because moisture and nutrient concentrations can differ between lots. The calculator includes reference values for common feeds, but those values are starting points; substitute a current laboratory result when one is available.
After converting each ingredient to DM, combine its DM contributions to calculate the ration total and weighted nutrient percentages. Pair that total with a species- and production-stage intake estimate from the DMI Estimator, then monitor feed conversion with the Feed Conversion Ratio Calculator.
Formula and units
dry-matter quantity = as-fed quantity × (DM % ÷ 100) [kg or lb DM]
ration nutrient % = Σ(DM quantity × ingredient nutrient %) ÷ total DM quantity × 100
DM% and nutrient percentages must be on the same basis. Mass units can be kg or lb, but do not mix them in one ration entry.
Worked example: why equal as-fed amounts differ
Use the verified calculator fixture: 10 kg corn silage at 35% DM and 10 kg alfalfa hay at 90% DM.
- Corn-silage DM:
10 kg × 0.35 = 3.5 kg DM. - Alfalfa-hay DM:
10 kg × 0.90 = 9.0 kg DM. - Total:
3.5 + 9.0 = 12.5 kg DMfrom20 kgas-fed. - Calculator result: the weighted crude-protein value is 16.86% DM basis.
The live calculator therefore shows that equal scale weights do not supply equal DM. It totals reference ingredients; it does not certify that this two-ingredient mix meets a specific animal’s complete requirements.
Use the calculator’s verified corn-silage and alfalfa-hay fixture
Feed Ration Builder
Build feed rations with multiple ingredients and see nutrient totals on a dry-matter basis with CP, TDN, and NDF breakdown.
Convert back to the amount delivered
Once a DM requirement or ration target is known, divide by the current feed DM fraction to determine as-fed delivery. Recheck that conversion when silage, pasture or hay moisture changes. A promising DM total still needs an appropriate nutrient target, minerals, vitamins, health and production context before it becomes a feeding recommendation.
Assumptions and limitations
- Reference ingredient values are averages; laboratory forage results take priority for a specific lot.
- The calculator’s nutrient totals are weighted DM calculations, not a complete diet formulation.
- DM intake varies with species, body weight, production stage, feed quality, weather and health.
- Minerals, vitamins, feed interactions and animal-specific requirements require a qualified nutrition review.
Common mistakes
- Comparing silage and hay by as-fed weight rather than DM.
- Mixing as-fed and DM-basis nutrient values in the same calculation.
- Leaving an old moisture result in the ration after changing a silage or forage lot.
- Treating a nutrient total as proof that the ration is balanced for a particular animal group.
Sources
The calculator’s reference feed composition and beef intake context are based on the National Academies’ Nutrient Requirements of Beef Cattle and its dairy reference values use the National Academies’ Nutrient Requirements of Dairy Cattle. Use a current forage test alongside these reference sources.