Farm Table says:
This fact sheet covers grass tetany in cattle, the causes of the disorder and what visual symptoms may occur. Grass tetany has a large number of causes so it is important for producers to be aware of symptoms so they can act quickly if it’s identified.
The items covered in this article were:
• What is grass tetany?
• When it’s most likely to occur
• The importance of magnesium, calcium, and phosphorus
• The effects of age, breed and production levels
• Other important factors
Key points were as follows:
• A mild cause of grass tetany is a deficiency in magnesium.
• A more severe case of grass tetany is where cattle have high amounts of potassium in their stomach which slows down magnesium absorption. High potassium levels can be caused from a range of factors (cattle graze pastures on soils naturally high in potassium, cattle graze pastures fertilized with inappropriately high levels of potassium fertilizer, cows are deficient in salt (sodium) or the diet is changed from hay or dry feed to lush pasture).
• Depending on the severity of the case, symptoms can range from froth around the mouth/nose, muscle spasms, twitching, stiff movement, staggering, overly excited, galloping or acting in a wild behaviour.
• Grass tetany is most likely to occur in late autumn or winter in southern areas.
• Cows that have a calf at foot or are close to calving are more likely to be affected by grass tetany.
• Calcium and phosphorus levels play an important role in magnesium absorption; low phosphorus levels can impact magnesium absorption. Some cows can be affected by low calcium concentration in the blood which leads to low magnesium levels and a decrease in cerebrospinal fluid.
• Other factors that can impact the chances of grass tetany in your herd are the age, breed, and high production demand on breeding cows, starvation, stress, soil health and time of calving.