By Jessica Hoover, Ag & Natural Resources Agent, WVUES Pendleton County
As spring arrives and pastures return to their lush green color, many livestock producers welcome the start of the grazing season. While this is a welcome sight after a long winter, it is important to understand the potential for grass tetany in ruminant livestock.
Grass tetany is a potentially fatal metabolic disorder caused by low levels of magnesium in the blood. This condition is most often seen in animals grazing rapidly growing spring pastures, as cool season grasses growing under cold, wet conditions are typically low in magnesium. Additionally, ruminant animals are relatively inefficient at absorbing magnesium from their diet due to the chemical processes required for its uptake (Van Saun, 2024). Pregnant and lactating animals are at an even greater risk, as their magnesium requirements are higher.
In addition to management practices, such as forage testing and soil testing to determine magnesium levels, feeding a high-magnesium, or “high mag,” supplement is recommended. Supplements that contain ingredients such as molasses, distillers’ grains, or other flavoring agents can increase palatability, which helps encourage intake and ensures animals consume adequate amounts of magnesium. Providing these supplements in late winter through early spring is recommended to help reduce the risk of grass tetany.
References: Van Saun, R. J. (2024). Grass tetany: A disease of many challenges. Penn State Extension. https://extension.psu.edu/grass-tetany-a-disease-of-many-challenges
