Splanchnic extraction of phenylalanine in mature mares was not affected by threonine supplementation

S. L. Mastellar, T. Barnes, K. Cybulak, K. L. Urschel

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


This study determined splanchnic extraction of phenylalanine at two intakes of threonine. Six Thoroughbred mares were supplemented with isonitrogenous amounts of either threonine or glutamate. Dietary threonine intakes were 119 (+Thr) and 58 (Basal) mg/kg/day, respectively. Each horse received each diet twice and each was studied once with an oral and once with an intravenous (IV) infusion of [1-13C]phenylalanine. A 2-h primed, constant IV infusion of [13C]sodium bicarbonate and a 4-h primed, constant infusion of [1-13C]phenylalanine, either orally or IV, were used to measure isotopic enrichments. Phenylalanine kinetics were not affected by diet (P > 0.05). Values for the splanchnic extraction of phenylalanine were 26 ± 5% and 27 ± 3% for the +Thr and Basal supplemented diets, respectively. These values will improve the accuracy of future equine indicator amino acid oxidation studies.

Original languageEnglish
Pages (from-to)190-192
Number of pages3
JournalVeterinary Journal
StatePublished - Jan 1 2016

Bibliographical note

Funding Information:
The information reported in this paper is part of a project of the Kentucky Agricultural Experiment Station (15-07-010) and is published with the approval of the Director. This project was supported by Agriculture and Food Research Initiative Competitive Grant No. 2012-67015-19448 from the USDA National Institute of Food and Agriculture. Preliminary results of this project were presented as an abstract at the 2014 Joint Annual Meeting in Kansas City, MO, USA.

Publisher Copyright:
© 2015 Elsevier Ltd.


  • Amino acids
  • Horse
  • Phenylalanine kinetics
  • Splanchnic extraction

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Veterinary (all)


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