Dry Matter Intake (DMI) Calculator
Calculate how much feed an animal needs to eat based on its body weight and feed moisture content
Animal Profile
Who is eating? We calculate DMI based on body weight percentage.
Don't know? Use our Weight Estimator tool.
Feed Type
What are they eating? Farmers usually feed "wet" grass, but nutrients are in the "dry" matter.
Auto-fills when you select a preset above, or enter manually.
Understanding Dry Matter Intake
Dry Matter Intake (DMI) is the amount of feed an animal consumes on a moisture-free basis. It's crucial for proper nutrition because nutrients are contained in the dry matter, not the water content of feed.
Why DMI Matters:
- Fresh grass can be 80% water - you need 5x more to get the same nutrients as dry hay!
- Underfeeding leads to slow growth and poor milk production
- Overestimating nutrition from wet feeds is a common mistake
How DMI is Calculated
DMI is calculated based on a percentage of body weight, adjusted for the animal's production stage:
~2.5% of body weight
~3.5% of body weight
~2.0% of body weight
~3.0% of body weight
Typical Feed Dry Matter Content
Different feeds have vastly different moisture content. Here are typical dry matter percentages:
| Feed Type | Dry Matter | Moisture |
|---|---|---|
| 🌿 Fresh Grass | ~20% | ~80% |
| 🍂 Silage | ~35% | ~65% |
| 🌾 Hay / Straw | ~85% | ~15% |
| 🥡 Concentrate | ~90% | ~10% |
DMI Calculation Formula
Step 1: Calculate Required Dry Matter
Required DM = Body Weight × (Target DMI% ÷ 100)
Step 2: Calculate As Fed Amount
As Fed = Required DM ÷ (Feed DM% ÷ 100)
📝 Example Calculation:
- • Cow: 400 kg (Beef/Fattening → 2.5%)
- • Feed: Fresh Grass (20% Dry Matter)
- • Required DM = 400 × 0.025 = 10 kg
- • As Fed = 10 ÷ 0.20 = 50 kg
💡 You need 50 kg of grass to get 10 kg of food!
Frequently Asked Questions
What is the difference between "As Fed" and "Dry Matter" weight?
"As Fed" is the actual weight of feed you put in the trough, including water content. "Dry Matter" is the weight of feed without any water - this is where the actual nutrients are. Fresh grass might be 80% water, so you need to feed much more to get the required nutrients.
Why do different production stages have different DMI requirements?
Different activities require different energy levels. Lactating dairy cows need more food (3.5% of body weight) because milk production requires significant energy. Maintenance cattle need less (2.0%) because they're not growing or producing milk.
How can I measure dry matter percentage of my feed?
The most accurate method is laboratory testing. For quick estimates, you can use a microwave oven method: weigh feed, dry it in short intervals, and calculate the weight difference. Commercial forage testers are also available for on-farm use.
What happens if I underfeed my cattle?
Underfeeding leads to reduced growth rates, lower milk production, poor body condition, weakened immune system, and reproductive problems. It's one of the most common causes of poor farm profitability.
