Ileal digestibility of amino acids in pea protein isolates, wheat-corn distillers dried grains with solubles, and short-season corn fed to broiler chicks

Abstract

The apparent ileal digestibility (AID) of amino acids (AA) in 4 pea protein isolates [PPI; experiment (Exp.) 1], 5 wheat-and corn-derived distillers grains with solubles (wcDDGS; Exp. 2), and 5 short-season corn (Exp. 3) samples for broiler chickens were determined. In addition, a reference wheat sample was included in each experiment to measure the repeatability of the ileal digestibility assay used. Birds (n = 180 for Exp. 1 and n = 216 for Exp. 2 or 3) were fed test diets from d 15 to 21 of age. Reference wheat and PPI were included in test diets at 91. 7 and 25%, respectively, as the sole source of AA, whereas wcDDGS and corn were combined with wheat in test diets at 47. 7% test ingredient (wcDDGS or corn) and 51% wheat as the sources of AA. Chromic oxide at 0. 3% was added in all diets as the indigestible marker. Each test diet was randomly assigned to 6 cages of 6 male birds each. On d 21, birds were killed and ileal digesta were collected to determine the AID of AA. The mean AID values for indispensable AA ranged from 86. 0% (Thr) to 94. 7% (Arg) for PPI, 50. 7% (Lys) to 79. 8% (Leu) for wcDDGS, and 73. 9% (Thr) to 95. 3% (Arg) for corn. Overall, the CV range for AID of AA was widest for wcDDGS (8. 1% for Met to 29. 4% for Lys) followed by corn (3. 0% for Met to 10. 7% for Thr) and then PPI (2. 7% for Lys to 6. 1% for Thr). For wcDDGS and corn, the within-sample variation (assay condition) was more than between-sample variation (feed differences), whereas the reverse was true for PPI. No differences were detected in the AID of CP and AA for reference wheat among experiments. © 2013 Poultry Science Association Inc.