How this hay calculator works
Extension intake tables are published on a dry-matter basis — a dry beef cow on average-quality forage eats about 2.2% of body weight in dry matter per day (Oklahoma State: 1.8% on low-quality forage up to 2.5% on high-quality). But hay isn't pure dry matter: it's typically ~88% DM. Our ruminant presets already do that conversion for you — e.g., the beef-cow preset shows 2.5% because 2.2% DM ÷ 0.88 ≈ 2.5% as-fed hay, which is what you actually buy and feed. The horse preset uses the University of Maryland's as-fed rule directly (a 1,000-lb mature maintenance horse eats about 20 lb of hay a day). The formula:
Total hay (as-fed) = weight × as-fed intake% × head count × days ÷ (1 − waste)
Waste is a combined storage + feeding loss and matters more than most people expect: a typical unrestricted ring feeder can run ~25%, ground feeding worse, and limiting access to a feeder can bring it near 10%. If your winters run long, add two to four weeks of cushion — hay is cheaper in September than in February.
Typical daily hay intake (as-fed, presets)
| Animal | Typical weight | As-fed intake (% BW) | Hay per day |
|---|---|---|---|
| Horse (maintenance) | 1,000 lb | 2.0% | ~20 lb |
| Beef cow (dry) | 1,300 lb | 2.5% (≈2.2% DM) | ~33 lb |
| Dairy cow (dry) | 1,400 lb | 2.3% (≈2.0% DM) | ~32 lb |
| Goat | 150 lb | 3.4% (≈3.0% DM) | ~5 lb |
| Sheep (ewe) | 175 lb | 3.4% (≈3.0% DM) | ~6 lb |
Growing, late-gestation, and lactating animals need more — sometimes much more. Lactating dairy cows in particular need a balanced ration, not a hay rule of thumb; work with your nutritionist. Forage quality shifts intake up or down.
Frequently asked questions
How much hay does a horse eat per day? About 2% of body weight — 20 lbs a day for a 1,000-lb horse, roughly 600 lbs a month, before waste.
How many round bales for one cow for winter? A 1,300-lb dry beef cow at ~2.2% of body weight in dry matter (≈2.5% as-fed) for 150 days eats about 4,900 lbs of hay; with 15% waste you should plan to buy roughly 5,700 lbs — 8 to 9 typical 700-lb 4×5 round bales.
Should I feed more hay when it's cold? Yes, and it's species-specific. For horses, University of Minnesota guidance: below a horse's lower critical temperature (~18°F for a winter-coated horse), energy needs rise about 1% for each additional °F drop — wind, wetness, shelter, and body condition move that threshold. Cattle guidance is similar in spirit. In a hard winter, the safest plan is extra hay on hand.
Sources
- University of Maryland Extension — Calculating Your Horse's Winter Hay Needs
- Oklahoma State University Extension — Nutrient Requirements of Beef Cattle (dry-matter intake by forage quality; bale weights)
- University of Minnesota Extension — Efficiently Feeding Hay to Cattle; Caring for Your Horse in Winter
- NC State & Penn State Extension — winter hay planning guides