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

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Edwards, Hardy Malcolm, III

Contributors dc:contributor

• Baker, David H.

• Biology, Animal Physiology

Language dc:language

eng

Identifier

(MiAaPQ)AAI9944842

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83653