Previous studies shown that in chickens the hepatic activities of the purine enzymes Xanthine Dehydrogenase and Nucleoside Phosphorylase and the uric acid excretion can predict the quality of the protein consumed in a very short time. In these studies even though the experimental time was short, the time used for the conditioning of the chickens was long and included five days with six chickens per cage and then five to six days for progressively changing the chickens to individual cages in order to avoid the stress associated with the isolation of the animals. Thus the purpose of this study was to determine the minimal time required to detect differences in these parameters after feeding a soy-met and a gelatin diet and eliminating completely the time required for the isolation of the chickens. Thus, 76 one day old Warren male chickens were placed in groups of six on a soy-met powdered diet during five days and on day six all the chicken were placed in individual cages and one halve was offered the same diet while the rest received a gelatin diet. Then on day 1, 2, 3, 5, 7, 10 and 15 after the diet change five chickens on each diet were sacrificed and the activity of the liver purine enzymes as well as the uric acid excreted were determined.(ABSTRACT TRUNCATED AT 250 WORDS)