Development of an Assay to Determine the Bioavailability of Potassium in Feedstuffs for the Young Pig

Abstract

A series of four trials was conducted to verify the published requirement of .26% total K in the diet and to identify response variables useful in an assay of the bioavailability of K in feedstuffs for the young pig. Purified diets were supplemented with K at four levels as KC2H3O2 in three trials and as KHCO3 in the fourth trial. In the first three trials, the requirement was estimated by least-squares analysis of a linear-plateau response of average daily gain. Additional measures in each trial were taken for linear response to dietary K levels. The three estimates of K requirement obtained were .30, .33 and .26% total K in the diet. These three estimates were not found to be inconsistent with the published value of .26% total K in the diet. Various urinary and hematological measures also were examined during the four trials for linear response to dietary K levels. Plasma K was the only hematological response to show a significant linear relationship to dietary K levels. Urinary K concentrations and daily excretion showed a highly significant linear response to dietary K levels. Based on these results, a K bioavailability assay using urinary K measures as the primary response variable and plasma K as the secondary response variable seems the most promising.