The next few weeks will see the turnout of cows on farms, many farmers on dry land have already taken advantage of recent dry spells and granted cows and calves access to the spring grass.
Now the attention must turn to the prevention of grass tetany at pasture as we enter a high-risk period.
The disease is not limited to affecting beef cows, as it can target dairy cows also. One of the causes is the turnout of cows to heavy, lush and low-fibre grass in paddocks. Paddocks that have received a heavy application of nitrogen (N) and potassium (K) will leave cows at risk.
Along with this, a contributor can be a change in the weather which will be expected throughout the next few days and weeks ahead.
Another trigger is stress, which can occur with a rapid change in diets i.e. switching from a silage-based diet to a grass-only diet. Cows that are coming into heat and bulling will also experience stress this spring in cases.
Symptoms
There are a few symptoms which can be linked to grass tetany that farmers should be wary of, as it can lead to sudden death in adult cattle. Famers need to keep a watchful eye on their cows when herding over the coming weeks.
Symptoms include:
- Muscle tremors;
- Cow may appear nervous or stiff in her legs;
- Frothing from the mouth;
- Staggering;
- Having a wide stare;
- Visual distress and spasming on the ground;
- Death.
Treatment
Identifying a case of grass tetany will warrant the call of a vet immediately. If it can be identified in the early stages, there is less of a risk of death occurring.
The cow should be administered magnesium sulphate. Depending on the severity of the case, the vet will identify if a sedation is needed in order to prevent brain damage.
Once treated, the cow should settle down and the farmer should see reduced excitability. Again, depending on the severity of the case, her recovery may vary especially if brain damage has occured.
Prevention
Like any health issue, ‘prevention is better than the cure’, while also being cheaper than having to call out your vet to treat cases.
The main prevention method is by providing the cow with a regular daily intake of magnesium during the risk period.
These can include feeding a concentrate containing Mg at pasture; offering cattle licks or blocks; Mg boluses supplementing Mg in the water supply; or pasture dusting with Mg.
However in the cases where a lick bucket is being used, remember that all of the cows may not ‘lick’ and consume the minerals – therefore a watchful eye at herding is still necessary.
If possible, the feeding of hay or straw at pasture will prevent a significant drop in rumen pH and slows down digestion to allow more time for mg absorption.