LINCOLN, Neb. — Fresh spring growth is a welcome sight for producers looking for animal forage. However, lush spring growth may be the perfect condition for a case of grass tetany. While turnout may be a ways off, mitigating this risk starts now.
Grass tetany is the result of low levels of magnesium in an animal’s blood stream. Low magnesium levels in lush, newly growing grass are often a main cause. In lactating animals, low dietary magnesium paired with a drain on calcium from milk production increases risk even more. Calcium aids in magnesium absorption. This means 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 six inches high before grazing. Legumes like alfalfa or clover are a good source of magnesium, so grazing mixed grass and legume pastures can help balance mineral demands.
While cultural practices can reduce risk, providing correct and adequate mineral supplementation may be the most certain remedy. Cattle should be consuming 3-4 ounces daily of mineral containing supplemental calcium and 10-13% magnesium oxide. This should start at least 30 days before grazing begins to ensure proper intake has been established.
Most high magnesium minerals 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.
— Ben Beckman, extension educator, University of Nebraska-Lincoln