How much hay for the winter?
Running out of hay in late winter is expensive: prices are highest when everyone needs it. A simple calculation from body weight, intake and the feeding period gives the tons and bales to buy or store, with a margin for waste.
The calculation
Hay per animal per day = body weight × dry matter intake % × share of ration from hay ÷ hay dry matter %
Total hay = animals × hay per day × days ÷ (1 − waste)
Bales = total hay ÷ bale weight
Example
30 cows of 1,200 lb, eating 2.5% of body weight in dry matter, fed hay only for 150 days, with hay at 88% dry matter and 15% waste:
- hay per cow per day: 1,200 × 0.025 ÷ 0.88 ≈ 34 lb;
- total: 30 × 34 × 150 ÷ 0.85 ≈ 180,500 lb, about 90 tons;
- with 1,200 lb round bales: 151 bales.
Typical intake
| Animal | Dry matter intake |
|---|---|
| Beef cow, mid-pregnancy | 2% to 2.5% of body weight |
| Lactating beef cow | 2.5% to 3% |
| Dairy cow | 3% to 4% |
| Horse, maintenance | 1.5% to 2% |
| Sheep and goats | 2.5% to 3.5% |
Cold weather raises energy needs: below the lower critical temperature, around 32 °F for a cow with a dry winter coat, intake rises by roughly 1% for each degree colder.
Waste adds up
Hay waste depends a lot on feeding and storage:
- round bales fed on the ground without a ring: 25% to 45%;
- with a cone or ring feeder: 5% to 15%;
- bales stored outside uncovered can lose 10% to 30% of their dry matter, mostly in the outer layer.
Storing bales under cover or on a well-drained base and feeding with a good feeder often pays for itself in one winter.
Weigh your bales
Round bales from the same baler vary widely: a 5 × 6 bale can weigh from 900 to 1,500 lb depending on the crop and density. Weigh a few bales on a scale or ask the seller for weights; buying by the ton is fairer than by the bale.
Quality matters too
Test hay for protein and energy. Low-quality hay may meet the dry matter target but still leave animals short of energy and protein, especially in late pregnancy.