Published 12 April 13

Hypomagnesaemia, or staggers, occurs when the input of magnesium is exceeded by the output, as a cow cannot store magnesium and relies on her daily dietary intake. Staggers can become a real issue in the spring when rapidly growing grass can have very low levels of magnesium. Add this to high milk outputs and the cow can quickly develop a magnesium deficiency, warns DairyCo extension officer Nicola Fair.

Obviously prevention is better than cure but if you do see the clinical signs of staggers it is important to act fast.  Look out for cows that are twitching, or seem unsteady on their feet. Affected animals can often be hyper excitable which can make them dangerous to handle, so take care. Clinical signs of an acute case can progress quickly and often the animal will just be found as a 'sudden death'.

Cows that show these signs need treatment immediately to prevent them deteriorating further, talk to your vet to come up with an appropriate treatment protocol.

Some calcium products for the treatment of milk fever also contain low levels of magnesium and can be given very slowly in the vein but black toped straight magnesium should only be given under the skin. Its black for a reason, too much magnesium too quickly will kill the cow you are trying to save!

If you think you may have cattle at risk of staggers talk to your vet to ensure you have the appropriate products in your medicine cabinet.

It's important to take steps to control the condition by supplementing magnesium either through your concentrate feed or direct into a TMR ration. Your feed supplier or nutritionist should guide you on the appropriate inclusion, but 60g/cow/day of calcined magnesite, somewhere in the ration, is the usual standard. 

If you're feeding calcined magnesite as part of a TMR it should be well mixed. The flour grade is likely to be more palatable and better absorbed, but can be difficult to handle and it is unpalatable without a carrier. Including the calcined magnesite in the parlour concentrate may be more straight forward if TMR feeding is not practical.

Avoid relying on a mineral block as there can be a huge variation in how much individual cows use them, leaving some cow still at risk of staggers

Adding magnesium chloride to the water may also be an option. It must be well mixed and not allowed to become too concentrated. There may also be problems with grazing cows on wet days as the cow will get most of their water from the pasture and drink less from the trough, therefore getting less magnesium.

To further minimise the problem management such as avoiding potash application in the spring is recommended, as this can lead to 'easy' uptake by the plant, offsetting the magnesium level in a rapidly growing grass plant.

Don't forget that slurry has high levels of potash so early doses on grazing can exaggerate the potential risk.  Also trying to minimise sudden ration changes and supplementary feed reductions are also good practices to adopt.