Grass Tetany – It’s that time of year again

Posted: May 6, 2015 | Written By: Heidi Doering-Resch, M.S. Form-A-Feed Beef Technical Services

grass fed beef cattle

Spring is my favorite time of year. Calves are on the ground or being born, feedlot cattle are hitting the trucks, and one can gauge how successful their year has been and be reminded of the beauty of new beginnings. Spring also brings rain, or at least it’s supposed to, so that we can produce crops to feed our livestock and our communities, and so that our pasture grasses can grow. Spring also brings the risk of grass tetany or grass staggers. In the beauty of everything becoming ‘green’ again we can sometimes forget about this nutritional disorder which if not prevented, usually has a negative outcome.

Grass tetany is when lush grasses high in potassium and water content and low in essential minerals for lactating animals such as magnesium and calcium are consumed. The draw of these minerals on a lactating cow causes a deficiency in blood magnesium levels which can cause staggering, twitching, irritability, muscle twitches, teeth grinding and eventually death. If not prevented, animals can perish in less than 2-3 hours after the onset of first symptoms. One must watch their herd when first introducing them to grass pastures and be certain your minerals are formulated correctly.

It is essential to provide cows with a mineral source that includes magnesium at about 8% of the labeled tag pending mineral consumption rate. Be certain that the mineral you are providing is both formulated for spring grasses and palatable. The problem with magnesium sources is they are often bitter tasting, so cows may not be as excited to consume them. In cases like this, it may be beneficial to utilize a high magnesium lic tub, such as 44-Magnum Lic w/Stealth 5®, or know the palatability of your loose mineral and check appropriate consumption levels to ensure cows are consuming it. You can always switch back to your loose mineral once tetany season is over (typically through May in the Midwest). You may need to add some palatability enhancers to your mineral to ensure consumption; just make sure you aren’t diluting your magnesium level in the process. For these reasons, we recommend going with a commercially formulated supplement or lic tub to ensure these items are addressed.

No one likes to walk pastures reminiscing in the new life of happy calves running tail-up and find their most productive cow(s) dead (it’s going to be the good mothers who milk well). Remember, grass tetany hits during spring and can easily be prevented with the proper supplementation.

Here’s hoping your spring pasture checks are filled with happy cows and high tailed calves.