ANSC Feeds Practice Exam

Which macromineral deficiency is most likely associated with grass tetany?

1. Sodium

2. Calcium

3. Potassium

4. Magnesium

The correct answer is: Magnesium

Grass tetany, also known as grass staggers, primarily results from a deficiency of magnesium in grazing animals, particularly ruminants like cattle. This condition is often seen when animals graze on rapidly growing grasses that are high in potassium and low in magnesium. In such scenarios, the magnesium levels in the animal's diet can become insufficient to meet their physiological needs, leading to severe neurological symptoms due to inadequate magnesium affecting muscle function and nerve transmission. Magnesium plays a crucial role in muscle and nerve function, including the regulation of neurotransmitters and muscle contractions. A deficiency can lead to symptoms such as muscle tremors, twitching, and, in severe cases, seizures or death. The timing of grazing—especially during spring when grasses are rapidly growing—also influences the risk of grass tetany since the nutritional balance in the forage changes dramatically. While sodium, calcium, and potassium are essential macrominerals as well, they do not directly contribute to the onset of grass tetany in the same critical way that magnesium does. Therefore, magnesium deficiency is recognized as the primary factor associated with this specific condition.