FEEDING FACTS
Grass Tetany There have been thousands of articles written about grass tetany, but since it is the most common time of year for this particular problem, it seems prudent to do yet another one, especially since there are some relatively new twists in the research on ways to prevent the disorder. Grass tetany is a most often fatal nutritional or metabolic disorder characterized by low blood magnesium levels. It is not as simple as just a magnesium deficiency and several factors can play a role. Some of those factors include low dietary magnesium, low salt intake, nutrient imbalances such as high nitrates or potassium, ambient temperature, frost or freezes, types of forages and fertilization practices just to name a few. Magnesium levels in the blood are important for many reasons and when it gets below a required threshold, animals tend to lose coordination, collapse and die within a short time. There are effective treat-
14 14 Cooperative Cooperative Farming Farming News News
ments if caught early on, but generally the first noticeable sign will be a dead animal. Prevention is the best strategy available. We normally see grass tetany on cool, cloudy, early spring days. Most often these days follow a warm spell which was followed by a freeze or frost and cattle are grazing young, tender, frost-damaged grasses that have been fertilized. Offering high quality hay or dry lotting cattle on such days can help in prevention, but may not always be possible. When cattle graze frost-damaged young grass, there is typically a spike in nitrate levels in the blood. Cattle generally use sodium to tie up and eliminate the excess nitrates, but when sodium levels are not sufficient, the next best option is magnesium. This, along with high levels of milk production, will cause severe magnesium deficiency in the blood stream and grass tetany becomes likely. Grass tetany is most often seen in middle-aged to
