Potassium (K) is the most important intracellular cation. It is involved in maintenance of acid/base balance and osmotic pressure. It also part of several enzymes participating in glycolysis and oxidative phosphorylation. In the body 90% of the potassium is intracellular in muscles and internal organs.
The most common roughages contain about 1.5 - 2.5 percent potassium in dry matter, which means 15 to 25 grams per kg dry matter. The content of potassium in grains is lower, 0.3 - 0.6 percent in dry matter. In rations with a normal amount of roughage there should be adequate amounts of potassium. When requirement for potassium is calculated, a value for availability of 50% is used.