Bioavailability of lysine in L-lysine.HCl.

O. A. Izquierdo, C. M. Parsons, D. H. Baker

Research output: Contribution to journalArticlepeer-review


True digestibility of lysine (LYS) in crystalline L-LYS.HCl and casein determined in cecectomized adult roosters was not significantly different from 100%. Subsequent 9-d growth assays were conducted to determine the bioavailability of LYS in casein, in L-LYS.HCl, and in a mixture of crystalline amino acids simulating casein's amino acid profile. Based on slope-ratio methodology, LYS bioavailability relative to casein was estimated to be 101.4 and 99.9% in L-LYS.HCl and in the casein-simulated amino acid mixture, respectively. Procedures also were developed for assessment of LYS bioavailability in crystalline L-LYS.HCl by comparing growth responses to intraperitoneally injected (IP-LYS) and crop-intubated LYS (CI-LYS) in chicks fed LYS-deficient corn-sesame meal diets. Graded increments of pH-adjusted L-LYS.HCl were administered twice daily in .5-ml doses during the course of 8-d growth assays. Chicks receiving CI-LYS also received .5 ml of IP saline at each dosing, and those receiving IP-LYS also received CI saline at each dosing. Slope-ratio multiple linear regression of gain (g) regressed on LYS administered (mg) was assessed for both ad libitum-fed and meal-fed chicks. Linear growth responses to LYS were obtained with both routes of administration and in both feeding regimens. The CI-LYS slopes ranged from 103 to 125% of those obtained with IP-LYS administration. These results support the view that crystalline L-LYS.HCl is 100% digestible and bioavailable.

Original languageEnglish (US)
Pages (from-to)2590-2597
Number of pages8
JournalJournal of animal science
Issue number10
StatePublished - Oct 1988

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics


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