Changes in Liver Xanthine Dehydrogenase and Uric Acid Excretion in Chicks during Adaptation to a High Protein Diet

Abstract

Studies were conducted to examine the relationship between changes in liver xanthine dehydrogenase with those in uric acid excretion during a 10-day adaptation period in chicks fed diets containing 25 or 75% isolated soybean protein. Food consumption, weight gain and liver nitrogen were also determined. Marked reductions in food consumption and weight gain were noted the first 24 hours in chicks fed the high protein diet as compared with chicks fed a control diet containing 25% isolated soybean protein. Consumption of the high protein diet and weight gain increased markedly after the initial 24 hours and remained at approximately 80% of the levels observed for control chicks throughout the remainder of the experiment. Liver weight, expressed on a body weight basis, was significantly increased in chicks fed the high protein diet for the first 2 days, after which time the differences between the 2 treatment groups largely disappeared. Elevated liver nitrogen levels were observed throughout the experiment for birds fed the high protein diet. Liver xanthine dehydrogenase activity increased twofold in chicks fed the high protein diet for 1 day and reached a maximum fourfold increase by day 4. A direct relationship between the elevated activity of hepatic xanthine dehydrogenase measured in vitro and the uric acid excretion was observed in these studies.