Enter the cow body weight and the diet Neutral Detergent Fiber (NDF, % of dry matter) into the Dry Matter Intake Calculator. The calculator will estimate the Dry Matter Intake (DMI) per day.
Related Calculators
- Dry Matter Calculator
- Carrying Capacity Calculator
- FCR Calculator
- Energy Corrected Milk (ECM) Calculator
- Fat Corrected Milk Calculator
- All Biology Calculators
Dry Matter Intake Formula
The calculator uses a different formula for each mode. Pick the one that matches the inputs you have.
Estimate DMI from body weight:
DMI = BW * (IntakePercent / 100)
Convert as-fed to DMI:
DMI = AsFed * (DM% / 100)
NRC 2001 lactating dairy cow:
DMI = (0.372 * FCM + 0.0968 * BW^0.75) * (1 - exp(-0.192 * (WOL + 3.67)))
where FCM = Milk * (0.4 + 0.15 * Fat%).
Rumen fill from NDF:
DMI = BW * (NDFcap / DietNDF)
Energy-based DMI:
DMI = EnergyRequired / DietNEl
- DMI: dry matter intake per day, kg or lb
- BW: body weight, kg or lb
- IntakePercent: expected DMI as % of body weight
- AsFed: feed offered or eaten on an as-fed basis per day
- DM%: feed dry matter percent (100 – moisture %)
- FCM: 4% fat-corrected milk, kg/day
- WOL: week of lactation
- NDFcap: NDF intake capacity as % of body weight, often near 1.2
- DietNDF: NDF concentration in the total ration dry matter, %
- EnergyRequired: NEl required, Mcal/day
- DietNEl: net energy for lactation in the diet, Mcal/kg or Mcal/lb DM
The Estimate DMI tab multiplies body weight by an intake percent, then optionally divides by feed dry matter to back-calculate as-fed pounds. The As-fed to DMI tab does the reverse, converting what an animal actually eats into the dry portion. The Dairy tab gives you three accepted prediction routes: NRC 2001 for early to mid lactation cows, NDF rumen fill for forage-limited diets, and an energy-balance check that asks how many pounds of a given diet are needed to cover a target Mcal load.
Typical DMI Values and Feed Dry Matter
Use these reference ranges to sanity-check your input percent and your output.
| Animal / stage | DMI, % of body weight |
|---|---|
| Beef cow, maintenance | 2.0 – 2.5% |
| Growing beef steer | 2.2 – 2.8% |
| Lactating dairy cow | 3.0 – 4.0% |
| Dry dairy cow | 1.8 – 2.0% |
| Mature horse, light work | 1.5 – 2.0% |
| Sheep or goat | 2.5 – 3.5% |
| Feed | Typical DM % | Moisture % |
|---|---|---|
| Grass or alfalfa hay | 88 – 90 | 10 – 12 |
| Corn silage | 30 – 38 | 62 – 70 |
| Haylage | 40 – 55 | 45 – 60 |
| Fresh pasture | 18 – 25 | 75 – 82 |
| Grain mix | 88 – 90 | 10 – 12 |
| Wet brewers grains | 22 – 28 | 72 – 78 |
Worked Example and FAQ
Example: lactating dairy cow. A cow weighs 650 kg, gives 35 kg of milk at 3.8% fat, and is in week 6 of lactation.
- FCM = 35 × (0.4 + 0.15 × 3.8) = 35 × 0.97 = 33.95 kg
- Lactation factor = 1 – exp(-0.192 × (6 + 3.67)) = 1 – exp(-1.857) = 0.844
- DMI = (0.372 × 33.95 + 0.0968 × 650^0.75) × 0.844
- DMI = (12.63 + 12.46) × 0.844 ≈ 21.2 kg/day
Example: as-fed to DMI. A steer eats 55 lb/day of corn silage at 32% DM. DMI = 55 × 0.32 = 17.6 lb/day. If the steer weighs 750 lb, that is 17.6 / 750 = 2.35% of body weight, inside the normal range.
Why use dry matter instead of as-fed? Water has no nutrients. Two feeds with the same as-fed weight can deliver very different amounts of energy and protein because their moisture content differs. Balancing rations on a DM basis removes that error.
What if my animal is eating more than 4% of body weight? Recheck the feed DM first. Wet feeds inflate as-fed numbers. If DMI truly exceeds 4%, the animal is likely a small, high-producing dairy cow or a young, fast-growing animal. Sustained intakes above 4.5% are uncommon.
Which dairy method should I pick? Use NRC 2001 when you know body weight, milk yield, fat, and stage of lactation. Use the NDF rumen fill method when forage quality drives intake, such as high-forage or low-quality diets. Use the energy method when you have a target Mcal requirement and a known diet density and want to size daily DM.
Does DMI include water? No. DMI is feed weight after all moisture is removed. Drinking water is tracked separately and is typically 3 to 5 times DMI on a weight basis for cattle.
