Endogenous amino acid flow in broiler chicks is affected by the age of birds and method of estimation

S. A. Adedokun, C. M. Parsons, M. S. Lilburn, O. Adeola, T. J. Applegate

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


The determination of ileal endogenous amino acid (IEAA) and total amino acid (TAA) concentrations is critical to standardizing amino acid digestibility coefficients. The IEAA and TAA flow in broiler chicks was measured on d 5, 15, and 21 at 2 geographical locations. Chicks were fed a nitrogen-free diet (NFD) or graded levels of casein (50, 100, or 150 g/kg of diet), which were assumed to be highly digestible. The IEAA and TAA flow (mg/kg of DM intake) on d 5 in chicks fed the NFD was higher (P < 0.05; Met = 154, Thr = 539) than values for d 15 (Met = 51, Thr = 274) and d 21 (Met = 50, Thr = 274). A comparison of the regression and NFD analyses showed higher (P < 0.05) flows on d 5 for those birds fed the NFD diet, with no differences between methods on d 15 and 21, with the exception of Lys, Met, and Glu (d 21). At all 3 ages evaluated, there was a linear increase (P < 0.05) in IEAA and TAA flows with increasing level of dietary casein. There was a decrease in IEAA and TAA flows that stabilized between d 15 and 21. The result suggests that the NFD and the regression method will give similar results on d 15 and 21. These observations also suggest that the relatively low apparent amino acid digestibility coefficients for broiler chicks at a younger age may be the result of a significantly high level of endogenous amino acid flow.

Original languageEnglish
Pages (from-to)2590-2597
Number of pages8
JournalPoultry Science
Issue number12
StatePublished - Dec 1 2007

Bibliographical note

Funding Information:
Partial funding for this project was supplied by US Poultry and Egg Association (Tucker, GA), Fats and Proteins Research Foundation (Alexandria, VA), Degussa Corporation (Kennesaw, GA), ADM Inc. (Decatur, IL), Novus International Inc. (St. Louis, MO), and Ajinomoto Heartland LLC (Chicago, IL).


  • Casein
  • Chick
  • Endogenous amino acid flow
  • Nitrogen-free diet
  • Regression

ASJC Scopus subject areas

  • Animal Science and Zoology


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