Pasture and Forage Minute: 2023 Grazing Plans, Preventing Grass Tetany

Apr 05, 2023

By Jerry Volesky

After a long winter of feeding hay, livestock producers are anxious for spring and the start of grass growth in their pastures. Last year’s drought conditions across the state left most pastures heavily used and short. A good sign is that longer-term precipitation forecasts for this spring are looking a little more optimistic. Now is the time to have a plan in place for your spring and summer grazing.  

It is known that the combination of drought and heavy grazing from last year can lead to reduced pasture production this year, even if we get near normal rainfall. Because of this, some reduction in stocking rate may be necessary.  

Another management recommendation that can be difficult to implement is to delay turnout this spring. This will allow those grasses to accumulate some growth and help in the recovery process. This has also been shown to result in more total forage production from those pastures. Another management tip for native pastures that were grazed first and into July in the 2022 season is to defer grazing of those pastures until later in the summer.

On native pastures, dominated by warm-season grasses, flash grazing or quickly rotating through a number of pastures in spring is also a method of capitalizing on early cool-season grass and weed growth. Remember that this must be for a short period of time and does not alter the suggestion of delaying turnout to your primary summer pastures.

Producers might also consider seeded annual forages as another option that can be used to supplement any grazing needs. Planning ahead can help make your forage season run smoothly.

Grass Tetany

By Ben Beckman

Fresh spring growth is a welcome site for producers looking for animal forage. However, lush spring growth may be the perfect condition for a case of grass tetany. While turn out 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 till 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 three to four 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.

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