It is stored in low levels in the cows 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 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
Magnesium also plays a vital role in calcium metabolism.
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.