DM (Dry Matter)
DM — Dry Matter — is the portion of any feed ingredient that remains after all moisture has been removed. It is the foundation for every meaningful nutrient comparison in cattle nutrition, because moisture varies enormously between ingredients (green fodder is 80% water; compound feed is 11% water) and would otherwise distort all comparisons.
How DM is measured
A weighed sample of feed is dried in an oven at 100–105°C until weight stops changing (typically 24 hours). The dried weight, divided by the original wet weight, gives the DM percentage.
DM % = (Dry weight / Fresh weight) × 100
Why DM matters
All nutrient comparisons — protein, fat, fibre, TDN, mineral content — are reported on a dry matter basis so that a wet ingredient can be compared fairly to a dry one.
Example: 25 kg of fresh green fodder (20% DM) and 5 kg of compound feed (89% DM) might seem like different sizes, but their dry matter contributions are:
- Green fodder: 25 × 0.20 = 5 kg DM
- Compound feed: 5 × 0.89 = 4.45 kg DM
Comparable amounts of nutrition.
Typical DM content of common feed ingredients
| Ingredient | Dry matter % |
|---|---|
| Soybean meal | 89–90% |
| Maize (grain) | 87–90% |
| Compound cattle feed | 89% (11% moisture max per BIS) |
| Dry fodder / straw | 88–92% |
| Maize silage | 30–40% |
| Green fodder (mature) | 22–30% |
| Green fodder (young) | 15–20% |
| Fresh berseem / lucerne | 14–18% |
| Sugarcane tops | 25–30% |
| Whole milk | 12–13% |
Dry matter intake (DMI)
The amount of dry matter an animal eats per day is called Dry Matter Intake or DMI. Targets:
| Animal class | DMI (% of body weight) |
|---|---|
| Lactating cow | 3.0–3.5% |
| Lactating buffalo | 2.5–3.0% |
| Heifer | 2.5–3.0% |
| Dry cow | 2.0–2.5% |
| Calf (4–6 months) | 3.0–3.5% |
For a 450 kg lactating cow, DMI target is approximately 13.5–15.8 kg per day.
Practical use
When formulating any ration, compute the DM contribution of each ingredient first, then sum them to get total DMI. The total ration's CP%, TDN%, fat%, and fibre% are calculated on the combined DM basis. This is how the DCP and TDN calculator and the ration cost calculator compute their numbers.