Magnesium is becoming increasingly important when examining Animal Welfare on the Farm

magnesium dairy cows

February 13, 2020

Magnesium plays a key role in muscle and nerve function in ruminants while Deficiencies are very rapid and can be fatal.

It is stored in low levels in the cow’s body and requires regular daily intakes. Magnesium can play a key role in enzymes, muscle and nerve function. In ruminants, the main problem we see is tetany (deficiency) and death. This is one of the most serious deficiencies because of the speed of onset to collapse and death.

When animals begin lactating the demand for magnesium can rise quickly. Sodium also helps in the digestion transport of magnesium from the gut into the blood.

There are a number of things that affect magnesium uptake:

  • Dry matter intake (can be affected by a number of things)
  • Potassium(too high)
  • Sodium (too little)
  • Ammonia or nitrogen high
  • Not enough fibre
  • CLA fats in spring grass can affect magnesium uptake

We must remember also it is estimated cows only ingest/absorb 20% of magnesium (average) so we must look at ensuring supplementation at-risk period is optimal.

We often call this deficiency grass tetany as it occurs at grass. It can occur at other times where intakes are affected. This can be weather-related or in stressful conditions like weaning time for suckler cows.

Magnesium is stored poorly in the body meaning that anything that affects intakes or absorption can cause the symptoms of hypomagnesia.

In cows, it is absorbed from the rumen and high potassium levels will affect its uptake, remembering both slurry and fertilzers can contain potassium.

With a high risk in grass-based systems and also with very little time when animals become deficient, we must manage this mineral.

Check out our video below from our Vetineary Consultant ‘Tommy the Vet’ regarding the importance of Magnesium for cattle health.