Fresh spring growth is a welcome sight for producers looking for animal forage.  However, this lush growth may also be the perfect set of conditions for a case of grass tetany.

Grass tetany is the result of low levels of magnesium in an animal’s blood stream, often brought on by diet due to low magnesium levels in lush, newly growing grass. Calcium also plays a role, helping improve magnesium absorption.

In lactating animals, this drain on magnesium and calcium from milk production throws these imbalances off even more.  As a result, high milk producing and older animals are most at risk for developing tetany.

To prevent tetany problems this spring, it’s best to wait until grass in pastures has grown to at least 6 inches high before grazing.  Legumes like alfalfa or clover, are a good source of magnesium, so a diet of mixed grass and legumes can help balance mineral demands.

While cultural practices can reduce risk, providing correct and adequate mineral supplementation may be the most fool proof solution. Cattle should be consuming 3-4 ounces daily of mineral containing supplemental calcium and 10-13% magnesium oxide at least 30 days before grazing begins, to ensure proper intake has been established. 

Most high magnesium mineral utilize magnesium oxide, which is bitter tasting and can reduce animal consumption.  Mix magnesium fortified mineral with salt into a complete package or feed with a highly palatable protein or energy supplement to improve intake

High magnesium mineral should be provided for animals until cool season grasses slow down growth and the levels of lush, fresh forage are reduced, around mid-May. 

Dealing with grass tetany in the spring doesn’t have to negatively impact your herd. Plan now to adjust grazing management or mineral supplementation for a tetany-free spring.

By Ben Beckman