Dry Matter Basis Calculator
Enter an as-fed (wet) nutrient percentage and the sample moisture percentage to convert it to a dry-matter basis (DMB%), for fair comparison of feeds, forage and crop nutrition.
輸入資料
計算結果
重點速覽：Dry-matter basis (DMB) converts a nutrient percentage measured on an as-fed (wet) basis into one measured on a dry-matter (water-removed) basis. Feeds, forage, silage and crops differ hugely in moisture (fresh grass up to 80%, hay only ~10%), so comparing as-fed percentages is distorted by water dilution. The dry-matter basis removes water first: DMB% = as-fed% × 100 ÷ (100 − moisture%), where (100 − moisture%) is the dry matter content. Expressing nutrition on a dry-matter basis lets feeds of different moisture be compared fairly — the standard in animal nutrition formulation and forage quality assessment.
計算公式
Dry matter content: DM% = 100 − moisture%.
Dry-matter basis: DMB% = as-fed% × 100 ÷ (100 − moisture%).
Reverse: as-fed% = DMB% × (100 − moisture%) ÷ 100.
$$DM\% = 100 - M\%$$$$DMB\% = \frac{AF\% \times 100}{100 - M\%}$$$$AF\% = \frac{DMB\% \times (100 - M\%)}{100}$$使用說明
- Enter the nutrient percentage on an as-fed (wet) basis (e.g. crude protein 30%).
- Enter the sample moisture percentage (0–100).
- The tool instantly gives DMB% and dry matter content for fair comparison across feeds of different moisture.
Typical feed moisture (approximate)
| Feed type | Moisture % (approx) | Dry matter % |
|---|---|---|
| Fresh grass | ≈ 80 | ≈ 20 |
| Silage | ≈ 65 | ≈ 35 |
| Hay | ≈ 10 | ≈ 90 |
| Grain (corn) | ≈ 14 | ≈ 86 |
| Concentrate feed | ≈ 10 | ≈ 90 |
Moisture varies with harvest timing and storage; values are typical. Use laboratory analysis for precise formulation.
理財情境案例
Hay crude protein on dry matter
Hay measured as-fed crude protein 30%, moisture 10%.
Dry matter content = 100 − 10 = 90%; DMB% = 30 × 100 ÷ 90 ≈ 33.33%.
On a dry-matter basis protein is ~33.3%, comparable with other feeds on the same basis.
High-moisture silage nutrient diluted
Silage as-fed crude protein only 8%, moisture as high as 78%.
Dry matter content = 100 − 78 = 22%; DMB% = 8 × 100 ÷ 22 ≈ 36.36%.
The 8% as-fed value becomes 36.4% on dry matter — high water heavily dilutes the as-fed figure, showing why a common basis matters.
常見問題
Why convert to dry-matter basis?
Feed moisture varies hugely and dilutes the as-fed percentage. Fresh grass is 80% water so crude protein looks low; hay has almost none so its number is high. Without removing water the two cannot be compared. The dry-matter basis (water removed) reflects true nutrient concentration — the standard in animal nutrition.
As-fed vs dry-matter basis?
As-fed is the actual state fed, water included — what the animal eats. Dry-matter basis removes all water and looks only at nutrient concentration in the dry matter. Formulation and comparison usually use dry matter to remove water interference, but actual feeding amounts must return to as-fed.
How to convert dry matter back to as-fed?
Reverse formula: as-fed% = DMB% × (100 − moisture%) ÷ 100. E.g. DMB crude protein 33.33%, moisture 10% → as-fed = 33.33 × 90 ÷ 100 ≈ 30%. After setting a formula you often convert back to as-fed to know how much (wet) feed the animal eats daily.
Where does moisture come from?
Most accurately by lab oven-drying (dry to constant weight; loss is moisture). Without lab data, use typical values by feed type (hay ~10%, silage ~65%, fresh grass ~80%) as estimates, but precise formulation should be lab-tested since even the same feed varies with harvest and storage.
Why does 100% moisture fail?
At 100% moisture dry matter is 0 (denominator 100 − 100 = 0), mathematically undefined, and it means the sample is all water with no dry matter to compute concentration, so the calculator returns 0. Feed moisture never reaches 100%; a near-100% value means the input is wrong — re-check the moisture data.
相關工具
參考資料
Content reviewed by the Hong Kong Calculator science team. Dry-matter basis per DMB% = as-fed% × 100 ÷ (100 − moisture%), the standard feed-nutrition conversion.