Work out how much hay or feed a cow eats per day, then scale it to your whole herd. Enter body weight and intake as a % of body weight, and you get daily, herd and total feed for the period, with optional cost.
Choose the animal (it sets a typical daily intake as a % of body weight), then enter weight, herd size and days. Intake here is on a dry-matter basis — adjust the % for your situation.
Daily feed per head = body weight × intake %. Multiply by the number of animals for the daily herd total, and by the number of days for the period total. Typical dry-matter intakes are around 2–3% for cattle and 3–4% for sheep and goats.
How Much Hay Does a Cow Eat per Day?
A common rule of thumb is 2 to 2.5% of body weight in dry matter each day. A 1,200 lb cow at 2.5% eats about 30 lb of dry matter. Hay is roughly 90% dry matter, so that is about 33 lb of hay as fed, before wastage. Lactating cows usually eat more than dry cows.
| Cow weight | Dry matter at 2% | Dry matter at 2.5% | Hay as fed at 2.5% (90% DM) |
|---|---|---|---|
| 1,000 lb | 20 lb | 25 lb | 27.8 lb |
| 1,200 lb | 24 lb | 30 lb | 33.3 lb |
| 1,400 lb | 28 lb | 35 lb | 38.9 lb |
Dry Matter Intake vs Feed as Fed
The intake percentage moves the answer most. Published figures are usually for dry matter, the feed left once the water is removed. Hay and grain are fairly dry, but fresh grass and silage are mostly water, so the same dry matter from silage weighs far more on the fork. Divide the dry matter amount by the feed’s dry matter fraction, from a forage analysis or the feed bag.
Getting Body Weight and Intake Right
Visual weight guesses are often well off. A livestock scale is best, and a weigh tape is a fair fallback for cattle and horses. Re-weigh growing animals regularly. Intake also shifts with stage and conditions:
- Lactating dairy cows, and ewes or does nursing young, eat considerably more than dry or maintenance animals.
- Cold, wet weather raises energy demand, while heat stress often cuts appetite.
- Poor-quality, stemmy forage is eaten in smaller amounts because it digests slowly.
Add a margin for wastage. Trampled or spoiled feed never reaches the animal, and losses are usually higher with bales fed on open ground than in covered feeders. Check what is left over each day to fine-tune your figure.
Quantity is not the same as a balanced ration. Protein, energy, minerals and clean water all matter, and needs differ between species. Sheep, for example, are sensitive to copper levels that suit cattle. Use the tool for budgeting and ordering, and ask a vet or animal nutritionist to check the ration itself. The Wikipedia article on fodder gives a useful overview of the main feed types.