NON-PROTEIN NITROGEN AND AMINO ACID UTILIZATION BY POULTRY by Howard Massey Frederick A Dissertation Submitted to the Faculty of the COMMITTEE ON AGRICULTURAL BIOCHEMISTRY AND NUTRITION (GRADUATE) In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY

Several nitrogen-containing dietary supplements were fed to chicks to study their effects on growth and tissue nitrogen products. An antibiotic mixture was added to the diet to determine its effect on the metabolism of nitrogenous compounds. In the first experiment, 2.0% protein equivalent was added as diammonium citrate (DAC) or isolated soy protein (ISP) to a balanced practical diet. DAC lowered gain and feed efficiency compared to ISP but neither was different from the control. Antibiotic did not alter growth rate compared to non-medicated groups, although adding barbituric acid caused a drop in body weight. Kidney arginase activity was increased by ISP or barbituric acid, but not by DAC. Plasma urea nitrogen was increased by each dietary treatment while plasma uric acid values were increased by feeding ISP and DAC, but not barbituric acid. In Experiment 2, DAC was fed at 2.5% and 7.75% protein equiv­ alents in a low protein diet. There was no difference in weight of chicks fed the lower DAC levels compared to the control group. Protein efficiency ratios (PER) gave indirect indication that nitrogen from DAC was utilized for protein synthesis. The high DAC level significantly lowered gain and N-retention, but was equal in PER to the low level. Kidney arginase activity was Increased by both levels of dietary DAC and was inversely proportional to weight gain. Both intestinal urea and urease levels were increased by dietary DAC and depressed by the antibiotic mixture. viil