Don’t Stand for Staggers Magnesium: How much is enough?

March 30, 2018

There are 15 minerals required by cattle for good health and productivity. One which cannot be stored and needs provided on a daily basis isMagnesium. Hypomagnesaemia (grass staggers) is a metabolic disorder of cattle caused by low magnesium levels in the blood. Grass staggers commonly occurs in suckler cows returning to heavily fertilised spring grass, however, it can also occur in Autumn during a late flush of grass. 

The recommended daily amount of magnesium for a suckler cow is between 0.2-0.3% of their diet. This means a cow consuming 15kg of DM/day requires at least 30g of Magnesium per day.

Supplementing Magnesium

There are a number of ways to get Magnesium into suckler cows, including, compounds, mineral supplements, Magnesium bullets, licks and blocks. For the purpose of this article the focus will be on compounds and licks and blocks.

Magnesium Rolls Versus Magnesium Buckets

Supplement Type


Magnesium supplied



ME Supplied


Davidsons Suckler Cow Rolls





Average of the top selling Magnesium buckets.





During service and early pregnancy, thin cows will struggle to conceive and hold. Autumn calvers should have a body condition score (BCS) 3 and spring calvers should be between 2.5-3 BCS. Change should be avoided during service and six weeks after positive PD testing. At the cost of an extra 6p/cow/day you will provide her with extra energy and nutrition in terms of ME and protein. The extra energy can help maintain body condition and improve fertility.

The suckler cow costs on average £700 per year, it is vital that she produces a viable calf every 365 days. A cow that is not pregnant for more than 12 weeks during the service period is a drain on resources. The two main ways of improving the bottom line in a suckler herd is to increase conception rates and reduce calving interval. In a study by Dugmore et al (2001), cows supplemented with at least 30g of Magnesium had a much improved services per conception and calving interval.

Author: Lauren Frew

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