Protein intake, uric acid metabolism and protein efficiency ratio in growing chicks

Changes in uric acid metabolism in chicks resulting from alterations in dietary protein intake have been correlated with dietary protein quality. Plasma uric acid levels, total uric acid excretion and protein efficiency ratio were measured in growing chicks fed diets containing 11%, 20%, 43% and 80% protein. A second degree polynomial with a coefficient of determination of 93% best described the relationship between dietary protein intake and total uric acid output. A second degree polynomial with a coefficient of determination of 58% best described the relationship between protein intake and dietary protein quality as measured by the protein efficiency ratio method. Plasma uric acid level was correlated, positively and linearly, with dietary protein intake and had a coefficient of determination of 42%. An integration of these relationships with purine biosynthesis and reutilization would enhance our knowledge of the control of uric acid production in the chick and possibly in human gout. The data demonstrate that total uric acid excretion and uric acid concentration in excreta may represent very useful methods of measuring dietary protein quality in the chick. The data also demonstrate that dietary protein level markedly affects uric acid production.