Studies on the Digestibility Coefficients and Biological Values of the Proteins in Poultry Feeds

Abstract

THE determination of the digestibility coefficients and of the biological values of proteins in feeding-stuffs is of very considerable practical interest to the poultry industry. In fowls the excretion of the urinary constituents along with the undigested materials through a common aperture renders it impossible to make direct estimation of the digestibility coefficients of feeds. The following brief review of the literature indicates the difficulties confronting the research worker on poultry nutrition. Fields and Ford (1900) and Brown (1904) estimated the amount of undigested nitrogen in poultry feeds by subtracting the uric acid and ammonia nitrogen from the total nitrogen in the mixed excreta. This method, however, gives misleading results for the uric acid and ammonia nitrogen only represents a fraction of the total urinary nitrogen. Coulson and Hughes (1930) from a review of the literature on the composition of avian urine concluded that the combined nitrogen from uric acid . . .