The Amino Acid Requirements for Maintenance in the Adult Rooster

Abstract

The nitrogen requirement for the maintenance of nitrogen balance in the protein-depleted and non-depleted adult male chicken has been determined. Whole egg protein and a free amino acid mixture in which 13 of the amino acids were supplied at the same level as found in whole egg protein served as nitrogen sources. The nitrogen requirement in the non-depleted bird was found to be 280 mg N/kg/day with either whole egg protein or free amino acids as the nitrogen source. In the protein-depleted animal the nitrogen requirement was half of that of the non-depleted animal or 140 mg N/kg/day from either whole egg protein or free amino acids. The metabolizable energy requirement at a nitrogen intake of 280 mg N/kg/day is not greater than 90 Cal./kg/day with whole egg protein as the nitrogen source. When free amino acids served as the nitrogen source the Caloric requirement was increased by at least 20 Cal. of metabolizable energy/kg/day. The adult rooster reached the endogenous level of nitrogen excretion after three days on a nitrogen free diet. The endogenous nitrogen excretion was 143 mg N/kg/day. The minimum nitrogen requirement based on the endogenous nitrogen excretion was 2.2 mg N/calculated basal Calorie/day. The results of the present study illustrate the importance of the state of body protein reserves on the nitrogen requirement of the adult male chicken.