Milk fever

Milk fever

What to look for

  • Downer cow shortly before or after calving
  • Most often found lying down, resting upright on the sternum with the head erect
  • Progresses to lying on their side
  • If not treated, will become unconscious and die within a few hours
  • In the early stages cows may be excitable and appear unstable when standing and walking


Low blood calcium level. Around calving time, cows need to mobilise large amounts of calcium from body stores such as bone. If this occurs too slowly the amount of calcium in the blood may fall below optimal levels resulting in milk fever.

Animals likely to be affected

Older, high producing cows in good body condition, shortly before or after calving. Occasionally occurs a few weeks after calving when cows are in oestrus.

Other diseases with similar signs

Confirming the diagnosis

Milk fever is usually diagnosed by the cow’s history and her response to treatment. If the cow is found dead, laboratory testing can help rule out other possible causes of sudden death.


Cows with milk fever need an injection of calcium (usually calcium borogluconate solution) preferably early in the course of the disease. There is little evidence that milk fever treatments containing additional minerals are any more effective than straight calcium products. If the cow is found early, oral calcium supplements or a calcium injection under the skin can be very effective. Injections under the skin can cause problems such as swelling and infection. Your vet may need to give a treatment into the vein but this requires careful monitoring to prevent heart failure.

Cows need to be watched after treatment because they can appear to recover and then have a relapse some time later. If a cow responds to treatment but is reluctant to get to its feet, it should be encouraged to rise as lying down for long periods can lead to further complications.

Risk factors

  • Cows calving in good or fat condition
  • Jersey breed
  • Cows with history of milk fever
  • High green feed diet during the transition period
  • Feeds that have had recent application of potash


Changing the cow’s diet during the transition period (from 4 weeks before calving until 4 weeks after calving) can reduce the occurrence of milk fever and other metabolic diseases, and optimise production and fertility. The simplest approach is to restrict the amount of green feed in the last 2 weeks of pregnancy and provide hay from sources that not recently been treated with potash fertilisers. At the other end of the scale cows may be fed a total mixed ration that includes a balance of dietary cations and anions.

More information

Transition feeding with limited effective fibre (PDF, 281KB)

Learn how a pre-calving diet sets up cows for lactation.

1. Meet her nutritional requirements, not just for maintenance, but also for final development of her foetal calf, and development of her udder.
2. Give her rumen microbes time to gradually adapt to the milker diet they will need to handle once she calves.
3. Reduce the chances of her suffering metabolic disorders and other health problems around calving, such as milk fever, grass tetany, ketosis, twisted stomach (displaced abomasum or DA) and retained foetal membranes (RFMs).
4. Enable her to eat more in the first few critical weeks of her lactation, and thereby lose less body condition and produce more milk.

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