Potassium Metabolism in Ponies

Potassium metabolism and some metabolic interractions of K, Mg and Ca were studied in a series of balance trials with ponies. The kidney was the primary pathway of K excretion. Increasing K intake markedly affected the renal excretion of K but had only small effects on fecal excretion. Increasing K intake increased retention and apparent digestibility of K. High levels of dietary Ca (3.4%) did not influence K metabolism but the highest level of Mg (.81%) increased the apparent digestibility of K. A level of 3.4% K did not decrease Mg, P or Ca digestibility and retention. The maintenance requirement of K was estimated to be 48 mg/kg of body weight. The estimates did not account for sweat and dermal loss of K. The small intestine appeared to be the site of greatest apparent net K absorption but a significant amount of K was absorbed from the large intestine.