Grass tetany could be looming for cattle, sheep

cattle pasture
Cattle on pasture

Are your pastures ready for spring and your livestock ready for pasture?

As fast as this year seems to be going, pastures will be greening up and it will be time to start grazing again. Although we haven’t had much of a winter so far, and I hope I am not jinxing us by mentioning it here.

Spring arrives soon

Soon it will be time to start preparing our livestock for lush green pastures. Last year was a tough year for getting stored forages harvested, especially first cutting hay.

Supplement energy

Some hay analysis I have seen this past year would suggest that many need to supplement energy to maintain body conditions during this last trimester prior to the spring calving and lambing season.


Last fall many pastures were overgrazed with the dry weather. With this combination, we should be watching both pastures and livestock closely. The transition from stored feed should be a gradual process so that animal performance does not suffer.

Hay supply

Maintain adequate quantities of dried hay in the ration until pastures have reached at least six inches in height and temperatures are consistently above 60 degrees Fahrenheit. This will also reduce early grazing damage to pasture and allow for soil moisture to be used for plant growth.

Forage stands

Removing animals from wet soils conditions to corrals or sacrifice lots will keep forage stands healthier and more productive into the growing season. Preparing for the early grazing season it is important that your mineral program complement the feeds you are feeding now.

Grass tetany

One of the major problems cattle and sheep producers encounter in the early spring is grass tetany, also known as grass staggers, spring tetany or lactation tetany.

So what causes grass tetany? Grass tetany typically occurs in the spring, but can occur in the fall or when you have rapidly growing, succulent, cool season grasses. This condition is a metabolic or nutritional condition in dairy, beef cattle and sheep with low blood levels of magnesium.

Magnesium levels

Lush green grasses are generally low in magnesium, but are made worse by having high potassium and protein levels. Mineral imbalances of high potassium and nitrogen along with low calcium, sodium and phosphorus levels can tie up magnesium in the soil making the problem worse.

Soil sampling

This is another reason for soil sampling and why you should apply fertilizer based on results, use no more potassium than needed since grasses are luxury consumers of potassium.


Feeding high magnesium mineral supplements is a preventative measure to reduce or prevent grass tetany. Cows require 20 grams of magnesium daily which can be accomplished through consuming three to four ounces per day of a mineral mix containing 12 to 15 percent magnesium.

Just because you provide high magnesium mineral mix doesn’t mean your livestock are in the clear. You need to monitor mineral intake and make sure all animals are consuming desired amounts. Magnesium alone can result in decreased palatability and decrease consumption.

Mineral mix

If livestock do not consume adequate levels from a free choice mineral mix, the supplemental magnesium can be combined with more palatable feeds such as dried molasses or soybean meal. Commercial mixes are available and a few University Specialists have provided home-made mineral mixes online. The high magnesium mineral supplements should be provided prior to turning livestock out onto lush pastures.

Feed before spring

Recommendations that I have found suggest provided these supplements two weeks to 30 days prior to turning out livestock onto pastures. High magnesium supplements do not need to be provided year round, but will not create any problems you feed it too early or late into the season.

Females at risk

Females are more prone to the disease especially the older heavy lactating females.
Steers, heifers, dry cows and growing calves are less susceptible, but can still contract tetany in the right conditions.

Keep your eyes open

Symptoms often include going off feed, nervousness, show muscle spasms, convulsions, irritability, lapse into a comma, aggressiveness and lastly death. Producers should keep a close eye on livestock in the early grazing season since these symptoms often occur rapidly.

Contact a veterinarian

Should you suspect grass tetany, contact your veterinarian immediately.

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