Nutritional Management For Grass Tetany

Magnesium oxide is the most common form of supplemental magnesium used to prevent grass tetany. So if your cattle graze pastures where they have experienced grass tetany, magnesium oxide supplementation is necessary. Magnesium oxide is not very palatable and has been characterized as having a bitter taste. Livestock are often unwilling to consume it at recommended levels, making free-choice supplementation of magnesium oxide to grazing cattle sometimes a challenge. Feed companies have remedied some of the intake concerns by adding intake stimulants to get consumption to levels necessary to combat grass tetany. Grass tetany mineral can be expensive, so getting intake to the recommended levels is important.

Grass tetany occurs in cattle most frequently in the early spring. Grass tetany, also termed hypomagnesemia, simply means a deficiency in Mg. Prolonged Mg deficiency results in excessive urination, erratic and nervous behavior (also called grass staggers). Grass tetany results from the consumption of lush forage, which has low levels of magnesium. The apparent depression in magnesium levels results from the high water content of rapidly growing plants. If left untreated, death can occur within several hours.

In northern regions, where producers feed more harvested forages, winter tetany can occur. Many grass hays and cereal grain hays can be low in Mg (< 0.15 percent) and high in potassium (K). When Mg levels in hay fall below 0.12 percent, cattle may become vulnerable to Mg deficiency. In addition, if calcium levels are low and potassium levels are high in these feed sources, winter tetany can result. Drought conditions often result in increased use of hays and crop residue alternatives. Drought-stressed forages typically are higher in K, which also contributes to the condition. Feeding a mineral supplement high in Mg should prevent problems associated with grass or winter tetany.

Finally, forages prone to causing grass tetany are deficient in magnesium and sodium and have an excess of potassium. Sodium is involved in transporting magnesium into cells, so it is critical to maintain adequate sodium (sodium can be supplied from salt) to facilitate proper magnesium utilization. Excess potassium consumption interferes with magnesium absorption from the gut, thus further exacerbating the condition of low dietary magnesium. In areas where grass tetany is prevalent, it is critical to consider dietary magnesium intake but also dietary levels of sodium and potassium