title: Splanchnic extraction of phenylalanine in mature mares was not affected by threonine supplementation.
abstract: 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-(13)C]phenylalanine. A 2-h primed, constant IV infusion of [(13)C]sodium bicarbonate and a 4-h primed, constant infusion of [1-(13)C]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.
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Mastellar
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: T
authors.initials: T
authors.lastname: Barnes
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506, USA.
authors.forename: K
authors.initials: K
authors.lastname: Cybulak
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40506, USA. Electronic address: klurschel@uky.edu.
authors.forename: K L
authors.initials: KL
authors.lastname: Urschel
mesh_terms: D000818:Animals; D019587:Dietary Supplements; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage; D006736:Horses; D010649:Phenylalanine / Q000008:administration & dosage / Q000378:metabolism*; D013912:Threonine / Q000494:pharmacology*; D014781:Viscera / Q000378:metabolism
chemical_list: D013912:Threonine; D018698:Glutamic Acid; D010649:Phenylalanine
keywords: Amino acids; Horse; Phenylalanine kinetics; Splanchnic extraction