Cattle Ration Calculator
Enter body weight, production stage, and at least one feed with amount fed to analyze your ration.
| Production stage | DMI (% BW) | CP % | TDN % |
|---|---|---|---|
| Dry cow | 1.8 | 7.5 | 50 |
| Late gestation (last 60 days) | 1.8 | 9.5 | 60 |
| Early lactation | 2.2 | 12 | 65 |
| Mid lactation | 2.2 | 11 | 62 |
| Growing calf | 2.4 | 14 | 68 |
| Stocker/yearling (2 lb/day gain) | 2.5 | 13 | 68 |
| Finishing | 2.4 | 12.5 | 72 |
NASEM/NRC planning figures. Work with your nutritionist for final rations.
Understanding dry matter vs. as-fed weight
Hay at 90% dry matter is not the same as silage at 35% dry matter — even if you feed the same number of pounds from the scoop.
A cow eating 30 lb of hay as-fed gets about 27 lb of dry matter. Thirty pounds of corn silage as-fed is only about 10.5 lb of dry matter. Protein and energy requirements are calculated on a dry matter basis. Feeding by as-fed weight without adjusting for moisture leads you to overestimate silage and underestimate hay.
The calculator converts each feed using its dry matter percentage. Use your forage test for exact DM, CP, and TDN — or start with the defaults and refine when lab results come back.
Protein and energy — the two numbers that matter most
Crude protein (CP) drives reproduction, immune function, and calf growth in utero. Protein-deficient cows lose body condition, breed back slower, and produce weaker calves. Excess protein is expensive and can increase water intake and urinary volume — rarely the main problem on range, but real in a feedlot.
TDN (total digestible nutrients) is the energy side. Energy shortfall shows up as weight loss, low milk, and slow gains. Late gestation and early lactation are the highest-risk windows — exactly when many ranchers feed the same hay they fed all summer without retesting.
Run your hay test numbers through the calculator above. Green means you are close. Red means you are buying a problem that shows up at calving.
Late gestation nutrition
Roughly 75% of fetal growth happens in the last 60–90 days of pregnancy. Protein and energy requirements jump in that window. A dry cow ration that held body condition in August will not automatically work in December for a March calver.
This is why the nutrition plan 90 days before calving is critical — see our calving season prep guide for the full timeline. Balance your late-gestation ration here before you start buying supplement in a hurry.
When you are planning spring pasture and fertilizer for the year ahead, our fertilizer rate calculator helps you estimate input costs alongside feed.
Common feed reference values
Use these as starting points until you have a forage test:
| Feed | DM % | CP % | TDN % |
|---|---|---|---|
| Bermuda grass hay, mature | 90 | 8 | 52 |
| Bermuda grass hay, leafy | 90 | 12 | 58 |
| Alfalfa hay | 90 | 18 | 60 |
| Corn silage | 35 | 8 | 70 |
| Ground corn | 88 | 9 | 88 |
| Distillers grains (wet) | 32 | 28 | 80 |
Values are typical ranges — your stack may differ. Always prefer lab results over tables.
For herd timing around calving, cross-check with the cattle gestation calculator and calving date planner.
Cattle Ration Calculator FAQ
How do I know what TDN my hay is?
Forage test from a lab. Until then, use Extension tables for your grass type and cut (mature vs. leafy).
What is a good protein supplement for late-gestation cows?
Cottonseed meal, soybean meal, or distillers grains depending on price and availability. Target 9.5% CP on dry matter in the last 60 days before calving.
How do I adjust rations for drought or poor hay quality?
Retest hay, lower pasture utilization, and increase supplement. Enter the actual CP and TDN from your test — not last year’s numbers.
Can I use this calculator for stocker cattle?
Yes. Select Stocker/yearling from the production stage dropdown.
How does a calf’s ration differ from a mature cow?
Calves need higher protein and more dry matter per pound of body weight. Use the Growing calf stage and enter actual calf weight.