Magnesium supplements vital to combat the ‘staggers’

IT will be a relief to get cows and calves out in this spring after the long winter housing period for most farmers.

With variable weather conditions, variable grass growth and some cows starting to come back in heat, cows can become stressed and may be prone to grass tetany, otherwise known as hypomagnesaemia or ‘staggers’.

Grass tetany is an acute magnesium deficiency in the blood of lactating cows (it also can occur in sheep) which is potentially fatal.

Cows basically need 20-40g of magnesium per day but magnesium is one of those minerals that does not recycle well and therefore animals have a daily intake requirement.

Any animal suffering from the condition will need immediate first aid therapy and/or veterinary attention.

If you do get a case of tetany it is important that some level of preventative measures are introduced to all other lactating animals in the group as experience has shown the symptoms to appear at herd level.

Any factor that leads to a decrease in the daily magnesium intake or absorption can predispose an animal to tetany. Well fertilised (with nitrogen & potash) grazed grass, that is lush and fast growing can often be low in magnesium (Mg) and with high digestibility it often passes through the animal so quickly the animals cannot absorb sufficient Mg.

Grass tetany can also occur in cases of reduced food intake.

This can arise due to bad weather conditions particularly cold wet weather.

Stress can also be a risk factor for grass tetany. This can occur due to transport of cows, cows on heat or where cows are being held tight on low grass covers and they begin to lose weight.

In autumn the stress of weaning can induce tetany in cows. Cases have been reported in cows that were housed even up to a week after weaning. Some soils will be naturally high in potassium and with high nitrogen applications these areas are more high risk.

Where grass tetany occurs cows become excitable, nervous, twitchy and become unsteady on their feet.

This can lead quite quickly to a stage where an animal will literally stagger and fall over, go into spasm or seizure on the ground and begin to froth around the mouth.

If this is left untreated it will lead to brain damage, heart failure and death within several hours. In many cases the only sign is an animal found dead in the field with the characteristic scratch marks on the ground around the legs and feet where the cow was in spasm prior to death.

It is due to the fact that Mg is involved in the electrical activity of both nerves and muscles that once deficiency occurs it will begin to affect the movement and temperament of the animal.

Treatment: Where you suspect you have a case of tetany you should contact your vet.

If you have magnesium sulphate (400ml) on hand you could administer it under the skin while you wait for the vet to attend the animal.

Depending on the severity of the case the vet may sedate the animal.

They will then generally administer calcium/ magnesium intravenously. If treatment is successful some cows could be up within the hour while some cows make take several hours to get back on their feet again.

Prevention is always preferable to treatment and the chance of grass tetany will be reduced if you can ensure a regular daily magnesium intake during the high risk period.

Mg can be supplied in feed, through the water supply, by rumen bolus, High Mg buckets or blocks and CalMag.