Spring Turnout – Supplementing lactating cattle with magnesium

Magnesium for cows


Although the annual rate of hypomagnesaemia/staggers/tetany (low blood magnesium) in UK dairy cows is less then 1%, one third of affected cows will die. These clinical cases are the tip of the iceberg; the rest of the group may also be sub-clinically affected. Hypomagnesaemia remains one of the very few veterinary emergencies on farms.

There are no hormonal mechanisms in the body to allow cows to regulate their blood magnesium levels. Maintaining blood magnesium levels is therefore entirely dependent on short term (daily) absorption of magnesium from the diet because the magnesium stored within the body is not readily mobilised by the cow.

Lactating cows (both beef and dairy) are particularly prone to hypomagnesaemia after turnout to spring grass because they have a high requirement for magnesium for milk production. The higher the milk yield, the higher the daily magnesium requirement.

Hypomagnesaemia can occur due to a low magnesium intake (due to low levels in grass, when grass alone is fed) or because the magnesium has a low availability (a poor efficiency of absorption) within the cow.

What affects the level and availability of magnesium in spring grass?

A low soil pH reduces magnesium uptake by the grass

High potassium levels in grass reduces magnesium availability in the rumen

Increased rumen pH after turnout reduces the solubility of magnesium, so less is absorbed by the cow

More rapid passage of food through the rumen reduces the time available for the absorption of magnesium.

There are 3 key criteria for an effective magnesium supplement:

The magnesium level in the formulation

Its palatability and therefore the intake realistically achievable – particularly important when the supplementary magnesium is to be fed free choice

The availability of the magnesium to the cow.

Crystalyx Cattle High-Mag contains 10.5% magnesium and is formulated with dehydrated molasses to ensure palatability even on lush spring grass. Independent research at Glasgow Vet School has confirmed the availability of the magnesium in Crystalyx Cattle High-Mag is superior to any other pure calcined magnesite source evaluated at Glasgow (so the magnesium is more efficiently absorbed by the cow).

And because Crystalyx Cattle High-Mag contains the full range of essential trace elements and vitamins often lacking in grass, the risk of other nutrient deficiencies is also reduced.

Crystalyx Cattle High-Mag is a palatable, cost effective self-help feed lick that can help to maintain normal blood magnesium levels this spring.

Find your nearest Crystalyx stockist here.