Expert advises producers about grass tetany disease

Wednesday, February 3, 2016

Livestock producers reminded to add magnesium to feed

Since the 1970s, after a bad outbreak of grass tetany, a disease that can cause death in livestock, Eldon Cole, livestock specialist with the University of Missouri Extension, has been advising producers this time of year to remember to add extra magnesium to their cow's minerals to protect them.

The disease, also known as winter tetanus, grass staggers or hypomagnesemia, usually affects cows six years and older. In its early stages, producers may notice atypical nervousness in their cow and over time, aggressiveness and staggering.

Given the seriousness of the disease, for 40 years Cole has stressed awareness of the disease, prevention measures, and dubbed January as grass tetany month.

"If not treated, she'll fall and be unable to right herself," Cole said. "She'll lie on her side and thrash around with her legs in a paddling motion. Soon, she likely will die with evidence showing her struggles."

Treatment includes giving intravenous solutions of calcium and magnesium. Oral drenches or enemas can be used. Cows should respond and be back on their feet shortly after treatment. Sometimes, cows may relapse and need another treatment.

But a positive tetany diagnosis can be tricky because symptoms can be confused with milk fever, or a lack of feed, Cole said.

"I still check with veterinarians and farmers each winter to see if any unusual amount of tetany is showing up, but it is certainly not to the degree we experienced 40 years ago," Cole said.

In the winter of 1973, a particularly bad case of tetany broke out.

"I've gone back in my notes to see how we handled that alarming problem back then," Cole said. "From December 15, 1972, until April 12, 1973, I logged 65 calls from farmers with tetany cows. I do not have any actual death count, but several died."

Most of the calls came from livestock producers in Barry, Greene, Christian and Stone counties and the first cases involved cows with two to three-month-old calves on them. Closer to April, tetany symptoms were in cows with two to three-week-old calves nursing.

"I recall at that time there were differing opinions as to what caused the problem to be so bad," Cole said. "Some felt it was a bacterial concern, but most agreed magnesium was involved."

Since that time, research has discovered imbalances between magnesium, phosphorous, nitrogen and potassium in the soil and forage, minerals crucial to body processes.

Cold, damp conditions and wet soils can also contribute, along with biological makeup.

"Genetics seems also to be involved," Cole said. "In the 1970s, a University veterinarian said that we killed off all the sensitive tetanus cows in 1973, so we should not have problems for several years. Blame was cast on farmers who over-fertilized. The problem involved the animal, soil, forage and weather."

To help prevent the disease, Cole always recommends feeding extra magnesium this time of year, through mid-April.

"If you feel your tetany risk is low, maybe just feed legume hay or early-cut grass hay," he said. "You might even have a forage test run on your hay to see if the magnesium level is 0.2 to 0.3 percent. If you choose to feed mineral, I suggest it contain 10 percent magnesium. If you mix magnesium into a protein/energy feed, the target should be to get one to two ounces per day of magnesium oxide into the cow."

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