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Metabolic disease

Any change in diet can upset the metabolic state of a cow. In particular the flush of spring grass growth can lead to increased problems as it is low in dry matter and certain minerals. Specific diseases to look out for include:


Hypomagnesaemia is pretty uncommon these days as most farmers are aware of the risk and try to pre-empt it. Staggers occurs most often in the spring when the grass has grown quickly, so contains low magnesium levels. Grass also contains a high moisture level and low fibre value causing a decreased gut transition time, thus decreasing the available time for the cow to absorb magnesium. This is especially a problem because the cow cannot store magnesium, meaning all its requirements are from the diet.

Typical signs to look out for are jittery, nervous cows in the early stages. This rapidly progresses to downer cows, fitting and death.

One affected animal potentially  means that there are other animals in the herd that are subclinically affected. For this reason herd treatment should be initiated.


The best way to prevent or treat subclinical staggers is to ensure sufficient magnesium content in the diet, through supplements (in either the feed or water) or a bolus. A 40 litre cow would typically need 40-50g magnesium a day. Providing rough fibre will also decrease gut transit time and increase the time available for nutrient absorption.

The treatment of a single case is by giving a bottle of magnesium under the skin and a bottle of calciject 5 in the vein. DO NOT PUT STRAIGHT MAGNESIUM INTO THE VEIN as it can damage the heart. It is also a good idea to give the cow an anti-inflammatory to minimize the risk of muscle damage from recumbency and fitting. 

Milk Fever

Hypocalcaemia is much more common, particularly in transition and freshly calved cows. It is caused when too much calcium is directed to the udder for milk production meaning that the blood levels drop dangerously.

This is further complicated when the cow is fed too many positive ions (eg potassium) and too few negative ions (eg chloride). These positive ions prevent mobilisation of calcium from the bones. Spring grass is particularly high in potassium and low in calcium and magnesium resulting in a high risk period.

Typical clinical signs of milk fever include:

  • Depression
  • Unsteadiness
  • Delayed calving
  • Low temperature/sweating
  • Recumbency

Again, seeing one clinical case will often mean you have many more subclinical cases in the herd. These animals may seem to be healthy but you will see an increased number of retained cleansings, metritis, ketosis and displaced abomasums.

Many farmers now choose to house their cows leading up to calving. This results in greater control of the diet and a limit in potassium intake from the grass.  Magnesium is also needed to help absorption of calcium.

To prevent milk fever magnesium chloride is often added to dry cow drinking troughs or the ration. There is also an added benefit from using chloride in that it acidifies the blood which also helps calcium mobilization.

The use of dietary cation-anion balanced diets and calcium boluses also have a place in preventing milk fevers; for further information please ask one of us.

Treatment of a single case of milk fever involves giving calcium in the vein and under the skin. There is also an argument to give phosphorus as an adjunct to calcium as these two minerals are linked.



There is a risk of ketosis (acetonaemia/slow fever) in cows in the first month of turnout as there are varying levels of dry matter and sugars in fresh grass.

Ketosis is caused when the cow’s energy intake is less than its energy requirements. This normally occurs when freshly calved and her dry matter intake can’t not keep up with the energy needed for milk production.

The cow is unable to compensate for this so starts breaking down her body reserves. Cows with a condition score of over 3 are particularly predisposed as their DMI after calving is greatly reduced. 

As usual - if it occurs in one cow, it is likely that there are many others within the herd that may be suffering subclinically.

Clinical signs include poor milk production, loss in condition and reduced feed intake. Some people can smell the typical “pear-drop odour” on the breath.

Prevention is better than cure as always. Ensuring good dry matter intake after calving is essential.

If you have a case please contact the practice to discuss your cow nutrition.