Uric Acid Excretion as an Indicator of the Amino Acid Requirement of Chicks 1

Summary

Studies were conducted with chicks fed crystalline L-amino acid and glucose-safflower meal diets to compare uric acid excretion with weight gain as indicators of the lysine requirement of chicks. Uric acid excretion decreased and weight gain increased as dietary lysine was increased to the requirement level, at which point both parameters plateaued with only slight changes occurring as the dietary lysine levels were increased beyond that point. Least-squares analysis of the uric acid excretion and weight gain data indicated good agreement between the requirement values obtained from the two parameters. Plasma uric acid concentrations followed a similar pattern as was noted with excreta uric acid. Xanthine dehydrogenase activity, on the other hand, was somewhat higher in chicks fed the higher levels of lysine in a glucose-safflower meal diet. The results of these studies suggest that uric acid excretion may serve as an accurate indicator of the amino acid requirement of the chick.