With the warmer weather and the winter moisture, your grasses out in the pasture will start their “Spring Greenup,” and things will start to look good again. It is during this time that forages come out of their dormant stage and begin growing rapidly again.
Though it may seem like the greatest time of the year, with all of the green across the pasture, it is not without its challenges and concerns. During this time of year, a particular problem known as grass tetany can cause issues with your cowherd.
For those of you not in the know, you may be asking, “What is grass tetany?” “What kinds of problems can it cause my operation?” and “How do I treat or even prevent it from happening?“. In regard to those questions, here are some things you should consider.
What causes grass tetany?
Grass tetany is a metabolic disorder that is caused by a low concentration of the mineral Magnesium in the blood. A producer can find it in all classes of cattle, and if it is not treated in time, it can be fatal.
This disease typically happens when cows graze rapidly growing, lush, green pastures. It can also occur when cows are grazing cereal grains. But it tends to happen more often during the spring with warm-season grasses.
During their early spring growth, forages will be low in many minerals, including Magnesium. It is during this time that forages do not absorb enough Magnesium from the soil. This problem is compounded by the fact that forages are mostly water at this stage. This problem means cows cannot consume enough of it to get the necessary minerals.
The risk of grass tetany also increases in lush, green pastures that are high in Potassium and Nitrogen. These particular minerals can interfere with the absorption of Magnesium by the cow.
The cow’s stage of production can also play a factor in the risk of getting grass tetany or not. Cows in the late gestation and lactation stages can get it because their body uses the Magnesium they consume for milk production.
Older cows tend to be more likely to get it than their young counterparts. This reason is because the older ones are not able to pull Magnesium from places like their bones in order to meet their body’s demand for it.
Symptoms
Visually diagnosing the symptoms of grass tetany can be tricky. This reason is because the symptoms can come on so fast that by the time you can see them, the cow will likely already be dead.
Some of the symptoms can be things like grazing away from the herd, increased irritability, muscle twitching, convulsions, decreased milk production, and even a staggering walk. Most of these symptoms are because Magnesium plays a role in neuromuscular function in cattle. So unless you are watching your herd very closely, it can be challenging to see the early signs of grass tetany.
If left untreated, cows will then lie down and begin a paddling-like motion with their legs. The final stages of the symptoms are that the cow will lie down, slip into a coma, and then die.
Ways to treat it
Being able to treat grass tetany in a fast manner can be difficult. This reason is because the death of the cow can occur relatively quickly. One day, the cow may look fine, but then the next, she will be dead.
It is necessary to restore the magnesium levels in your herd’s blood if they have grass tetany. Preventing it from getting worse requires immediate action. There are a few different ways that you can go about doing that.
One way that this can be done is by a veterinarian giving an intravenous injection of Magnesium and Calcium solution to the cow. This injection can work during the early stages of the disease when time is not as critical as later on.
Suppose it is a severe problem, and you must act quickly. In that case, a producer can inject the Magnesium/Calcium solution under the skin. However, if this is something that you are not entirely used to, I would not recommend doing this yourself.
There are also some oral options that are available to the producer. These options are generally to prevent any of your cows from relapsing. These oral sources of Magnesium are:
- A Magnesium oxide powder for putting onto either feed or on the pasture
- Magnesium lick blocks
- Slow-release capsules
- Magnesium sulfate or soluble magnesium chloride that can be added to hay or silage
- Adding Magnesium to concentrates
Your veterinarian or local feed store can provide you with these products.
Ways to prevent grass tetany
When it comes to this particular disease, taking steps to prevent it from showing up in the first place is really the best option. Death can come so quickly that you may not even get the chance to treat it. As they say, “An ounce of prevention is better than a pound of cure.”
The general rule of thumb is to provide a mineral or lick tub with additional Calcium and Magnesium. One with at least 8%-12% Magnesium is the best one to go with. This type of tub will provide the minerals your cows will need and keep grass tetany away.
Issue with Magnesium
An issue with increasing the amount of Magnesium offered to cattle is that the cattle will not consume enough to be of any help. This problem is caused by the fact that Magnesium is relatively low in palatability, so cows are less likely to eat it. Because it is so unpalatable, it is recommended only to put a high-Mg mineral when they need it. Another way to make it more likely to be consumed is to mix the mineral with a more palatable feed or salt. Adding salt will also mean the sodium requirement is being met, which will help with Magnesium absorption.
If you would like to read more about the importance that minerals play in your cow’s diet, then check out one of my previous posts, “What you don’t know about minerals can hurt”.
Now, on to when you should be putting the minerals out. According to the Veterinary Quarterly Review published by the Texas AgriLife Extension service, you should provide the supplement 30 days before grass tetany typically occurs. This timeframe means either in late winter or early spring.
During this time, your forages are mostly water. Increasing your cows’ roughage and energy intake is a good idea. Forages will be nearly 75% water at this time, which will dilute any nutrients they may provide
Another tactic you could use is reducing your forage’s Potassium and Nitrogen levels. Though these are also necessary nutrients, too much of them can have a negative impact on Magnesium absorption. Test your forages to find out what these levels are.