Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs

D. Y. Yu, M. D. Lindemann, A. D. Quant, Y. D. Jang, R. L. Payne, B. J. Kerr

Research output: Contribution to journalArticlepeer-review

Abstract

Two 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio for growing pigs; 1 experiment fed diets supplemented with or without an antibiotic. The primary response variables in both experiments were ADG, ADFI, G:F, and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys ratio detected using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with an antibiotic. This experiment used 120 crossbred pigs that were blocked by sex and initial BW (24.13 ± 2.72 kg) and allotted to 6 SID Trp:Lys ratios in 4 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (13.08%, 14.06%, 15.04%, 17.00%, 18.95%, and 20.91%) with a constant SID Lys level of 0.655%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly (P < 0.05) and quadratically (P < 0.05). Linear broken-line analysis yielded optimum SID Trp:Lys ratios of 17.93% (P < 0.001) and 16.17% (P = 0.009) for ADG and PUN, respectively, resulting in a mean optimum SID Trp:Lys ratio of 17.05%. Experiment 2 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. It used a total of 324 crossbred pigs (initial BW: 30.81 ± 3.56 kg) that were allotted to 6 SID Trp:Lys ratios in 6 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (12.52%, 14.86%, 17.20%, 19.54%, 21.88%, and 24.22%) with a constant SID Lys level of 0.67%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly (P < 0.001) and quadratically (P < 0.001) regardless of antibiotic inclusion. There were no differences by the antibiotic treatment in ADG, ADFI, G:F, or PUN concentrations (P > 0.49) and no interactions between antibiotics and Trp:Lys ratios (P > 0.29). When the data for all pigs were pooled for the various Trp:Lys ratios, the optimum SID Trp:Lys ratios for ADG and PUN based on linear broken-line analysis were 14.58% (P < 0.001) and 14.54% (P < 0.001), respectively, resulting in an optimum SID Trp:Lys ratio of 14.56% as the mean of the determined optima for ADG and PUN responses. These results demonstrate that the optimum SID Trp:Lys ratio for 30- to 50-kg growing pigs is not impacted by the dietary inclusion of an antibiotic as long as the diets are formulated on an SID AA basis.

Original languageEnglish
Pages (from-to)5516-5523
Number of pages8
JournalJournal of Animal Science
Volume95
Issue number12
DOIs
StatePublished - Dec 2017

Bibliographical note

Publisher Copyright:
© 2017 American Society of Animal Science. All rights reserved.

Keywords

  • Antibiotic
  • Lysine
  • Pigs
  • Standard ileal digestible tryptophan:lysine ratio
  • Tryptophan

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

Fingerprint

Dive into the research topics of 'Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs'. Together they form a unique fingerprint.

Cite this