Maintenance Requirements and Efficiency of Utilization of Protein, Threonine, Lysine and Sulfur Amino Acids in Chicks Fed Diets Based on Crystalline Amino Acids or Soybean Meal
Edwards, Hardy Malcolm, III
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https://hdl.handle.net/2142/83653
Description
Title
Maintenance Requirements and Efficiency of Utilization of Protein, Threonine, Lysine and Sulfur Amino Acids in Chicks Fed Diets Based on Crystalline Amino Acids or Soybean Meal
Author(s)
Edwards, Hardy Malcolm, III
Issue Date
1999
Doctoral Committee Chair(s)
Baker, David H.
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Language
eng
Abstract
Broiler chicks were fed chemically defined crystalline amino acid diets containing graded levels of either L-threonine (Thr), L-lysine·HCl (Lys), DL-methionine (Met), or L-cystine (Cys) during the period 10 to 20-d posthatching. At least six doses of the limiting amino acid representing from 5 to 95% of its ideal level for maximal weight gain and feed efficiency were included as treatments. Other amino acids were maintained at minimized excess levels that were 15% (of ideal) above the various doses of the limiting amino acid. Following 10 d of feeding and a 24-h fast, chicks were killed for whole-body protein and amino acid analysis. Using pen accretion means, protein accretion and accretion of the limiting amino acid were linear functions of intake of the limiting amino acid from 5 to 95% of ideal for Thr and Lys and from 5 to 70% of ideal for Met and sulfur amino acids (SAA). Slope of the limiting amino acid accretion line indicated 82% of Thr was recovered in whole-body protein, 79% of Lys, 68% of Met, and when calculated together 52% of SAA. Maintenance requirements for zero accretion of the limiting amino acids were, as follows: Thr, 45.7 mg/d per kg0.75; Lys, 89.1 mg/d per kg 0.75; and SAA, 15.3 mg/d per kg0.75. Maintenance requirements for zero protein accretion of the limiting amino acids were all lower: Thr, 39.2 mg/d per kg0.75; Lys, 6.9 mg/d per kg 0.75; and SAA, 9.4 mg/d per kg0.75. As doses of the limiting amino acid increased in the diet, whole-body concentrations of other indispensable amino acids increased whereas glycine and proline tended to decrease. Protein quality evaluation of soybean meal (62.7% CP) processed from a genetically modified high protein soybean revealed an increase in all essential amino acids, and amino acid digestibility values were comparable to a soybean meal (47.5% CP) processed from a conventional soybean variety. Results of this study indicated that the high protein soybean meal has considerable advantages over conventional soybean meal as a feed ingredient for broiler chickens.
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