Hypomagnesaemia (grass staggers) is a metabolic disorder of cattle and sheep caused by low magnesium levels in the blood. It commonly occurs in lactating cows when they are turned out to grass in the spring. It can also occur in autumn when there is a late flush of grass growth.
The condition typically occurs on a cold/wet day when the cattle do not consume as much grass as normal. The disease can occur in both adult cattle and calves of beef and dairy breeds.
Staggers results from an inadequate absorption of magnesium from the digestive system. It is a difficult disorder for the animal to control since there are very little magnesium reserves in the animal's skeletal structure, thus a daily intake is required.
The risk is highest early in the grazing season given the lushness and low mineral content of spring grass, especially if it is rich in nitrogen and potash, as this can slow down magnesium absorption in livestock.
Other causes include:
The symptoms of grass staggers are:
An early warning sign can be a reduction in milk yield. However, often the attack comes on so rapidly that the animal shows no symptoms.
Remember - any individual incidents in the herd will mean that magnesium levels are low in the entire herd as often only one or two animals in the first instance will exhibit major symptoms.
It's essential to have a regular supply of magnesium in the diet, either from free access high magnesium minerals (Magnesium Oxide) or preferably mixed into supplementary feed such as in-parlour concentrates for dairy cows. Supplementary feeds such as low quality silage, hay or sugar beet pulp which are high in fibre are useful in slowing down the rate of passage of digesta through the intestine, and thus, increases the length of time for absorption of magnesium to occur. The absorption of magnesium is reliant on the inclusion of sodium in the ration, be that within the mineral or fed in a supplementary form (ground rock salt, PDV salt or lump rock salt).
In the event of an attack of grass staggers the vet will administer magnesium to cure the condition.
Other ways to prevent staggers:
Calcined Magnesite ('Cal Mag') - The most commonly used and economic source of supplementary magnesium for ruminant livestock. The magnesium in Cal Mag is highly available during digestion. Due to its poor palatability, Cal Mag is normally included in TMR rations, minerals, mineral buckets, compounds or blends.
Magnesium Chloride flakes - Because of its high solubility, Mag Chloride is normally administered via the drinking water. It can also be added to the TMR diet.
High Magnesium Cattle buckets - A convenient means of supplying magnesium, and other essential minerals and vitamins, in situations where it is not possible to use conventional powdered minerals, eg. sheep at grass or suckler cows.
High Magnesium Sheep buckets - As above but formulated with zero copper.
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