Guide
What Is Silage? A Simple Guide for Dairy Farmers
How silage is made, why farmers use it, and how to store and feed it without waste.
Silage is green fodder, such as maize, that is chopped, packed tight and sealed without air, so it ferments and keeps as moist, nutritious feed for months.
Why dairy farmers make silage
- It stores green fodder from the season of plenty for the months when fields are bare.
- Cows get the same feed every day, which keeps milk yield steadier.
- It can cost less per kg than buying fodder in the lean season.
How silage is made, step by step
- Harvest at the right stage. Maize is usually cut when the grain is at the dough to early dent stage, when the whole plant is around 30–35% dry matter.
- Chop short. Short pieces pack tighter and squeeze out more air.
- Fill fast and pack hard. Spread thin layers and drive over them repeatedly. A common target is about 14 lb of dry matter per cubic foot, around 640 kg of silage per m³ at 35% dry matter.
- Seal at once. Cover with plastic and weigh it down with tyres or soil, so no air gets in.
- Wait. Bacteria turn sugars into acid, which preserves the crop. Open after about three weeks.
How much is lost?
Some feed is always lost. In one study of bunkers and bags, dry matter losses were about 5–11%, highest in the loosely packed top layer and in bags. Silage packed below the density target can lose 17–20%.
Feeding silage
- Introduce it slowly over a week, mixed with the usual fodder.
- Take a full, clean slice from the face every day and feed it fresh.
- Throw away mouldy or rotten silage. It can make animals ill.
Plan your pit with the silage calculator, and see what silage costs in your ration with the feed cost calculator.
Questions farmers ask
What is silage made of?
Usually green maize (corn), sorghum, oats or grass, chopped and stored without air while it is still moist.
Is silage better than hay?
Silage keeps more of the crop's feed value when the weather makes drying hay difficult, and it gives green feed through dry months. Hay is easier to store, move and sell in small amounts. Many farms use both.
What is the difference between silage and haylage?
Haylage is grass or legume that is wilted to a drier state before storing airtight, so it sits between silage and hay. Silage is stored wetter, usually around 30–35% dry matter for maize.
How long does silage take to be ready?
Fermentation settles within a few weeks of sealing. Most farmers wait about three weeks before opening a pit.
Sources
- UNL CropWatch, Estimating the tonnage of silage in a bunker silo
- SARE, Dry matter loss in bunker and bag silage
Last reviewed 2026-10-10.