🔄 Feeding
How dairy cows are fed: about 18 kg of feed dry matter a day at peak lactation; feed is roughly half of a dairy farm's costs.
Feeding is the diet dairy cows receive on the farm: fresh grass, silage, hay, compound feed and grain. At peak lactation, 8–10 weeks after calving, an Irish herd eats on average about 18 kg of feed dry matter per cow per day. The diet determines how much milk a cow gives and what that milk is like.
Teagasc gives an example: a 550 kg cow gives 25 kg of milk with 4.3% fat on a diet of 80% grass and 20% concentrate. Fibre (NDF) should be 32–36% of dry matter — with less, the risk of acidosis rises — and crude protein 15.5–17%. Spring grass is almost 40% more nutritious and 70% richer in protein than average silage.
On large farms, feeds are mixed into a total mixed ration (TMR) so the cow cannot pick out favourites and the rumen bacteria get the same food all day. Feed should be available about 20 hours a day, with about 5% left before the next feeding. Water matters just as much: a cow weighing about 680 kg drinks 70–135 L a day, and 120–200% more in hot weather.
Why it matters to you. Feed is the biggest cost: in Northern Ireland in 2023, concentrates and forage made up about half of all dairy farm costs, and that shows in the price of milk. The diet also shapes the fatty-acid profile: milk from cows on pasture has more omega-3 and beta-carotene. But no official body considers milk from silage-fed cows harmful.
Facts
| Main use | Nutrients and protein for milk yield 1 |
|---|---|
| Duration | Peak intake — 8–10 weeks after calving 1 |
| Country | Ireland — Teagasc data 1 |
How it connects to milk
Links
- Feeds
- 🐄 Cow
- Fed on
- 🌾 Hay, 🌾 Silage, 🌾 Compound feed
- Next step
- 🔄 Milking
- What it yields
- 🥛 Milk
- Who works with it
- 👷 Animal scientist, 🧑🌾 Farmer
- Part of
- 🏡 On the farm: feed, grazing and milking
- In other topics
- 🐝 Sheep grazing in vineyards
Frequently asked questions
How much does a dairy cow eat?
At peak lactation, about 18 kg of feed dry matter a day (Teagasc). First-lactation heifers eat about 15 kg.
What is TMR?
Total mixed ration: all feeds are mixed so the cow cannot pick out individual ones and the rumen gets the same food all day.
How much water does a cow drink?
A cow weighing about 680 kg drinks 70–135 L a day depending on yield and temperature, and 120–200% more in hot weather.
Is milk from silage-fed cows harmful?
No. The diet changes the fatty-acid profile of milk — pasture milk has more omega-3 — but not its safety.
Why is grass better value than silage?
Spring grass is almost 40% more nutritious and 70% richer in protein than average silage, and costs half as much.
What to read next
- 🐄 Cow — The world's main source of milk: ≈81 % of global milk output (FAO). High-yielding cows give up to 60 kg of milk a day.
- 👷 Animal scientist — A specialist in feeding, housing and breeding animals; according to the BLS the US has 3,400 animal scientists, and the EU defined a "breeding programme".
- 🌾 Hay — Hay is grass or legume forage cut and dried as livestock feed; dairy farms often make it from alfalfa, and it is baled at 20% moisture or less.
- 🔄 Milking — 2–3 times a day, by hand or by machine.
- 🐝 Sheep grazing in vineyards — Sheep grazing in vineyards means a flock eating the grass and weeds between vine rows in winter while adding nutrients to the soil.
Similar
Sources
- Teagasc (2025). Nutrition of the spring calved dairy cow in the early lactation period
- New Mexico State University Extension, Guide D-107 — Water for Dairy Cattle
- University of Kentucky Cooperative Extension ID-141B — Managing the Total Mixed Ration
- Irish Farmers Journal (2024). Half of all cost on NI dairy farms is feed
- Alothman M. et al. The «Grass-Fed» Milk Story. Foods 8(8):350, 2019