Amino acid supplementation does not alter whole-body phenylalanine kinetics in Arabian geldings.
Abstract: Stable isotope infusion methods have not been extensively used in horses to study protein metabolism. The objectives were to develop infusion and sampling methodologies for [1-(13)C] phenylalanine and apply these methods to determine whether the addition of supplemental amino acids to a control diet affected whole-body phenylalanine kinetics in mature horses. Arabian geldings were studied using a 6-h primed (9 μmol/kg), constant (6 μmol · kg(-1) · h(-1)) i.v. infusion of L-[1-(13)C] phenylalanine, with blood and breath sampled every 30 min, to measure whole-body phenylalanine kinetics in response to receiving the control diet (n = 12) or the control diet supplemented with equimolar amounts of glutamate (+Glu; 55 mg · kg(-1) · d(-1); n = 5), leucine (+Leu; 49 mg · kg(-1) · d(-1); n = 5), lysine (+Lys; 55 mg · kg(-1) · d(-1); n = 5), or phenylalanine (+Phe; 62 mg · kg(-1) · d(-1); n = 6). The plasma concentrations of the supplemented amino acid in horses receiving the +Leu, +Lys, and +Phe diets were 58, 53, and 36% greater, respectively, than for the control treatment (P < 0.05). Isotopic plateau was attained in blood [1-(13)C] phenylalanine and breath (13)CO(2) enrichments by 60 and 270 min, respectively. Phenylalanine flux (+20%) and oxidation (+110%) were greater (P < 0.05) in horses receiving the +Phe treatment than in those fed the control diet. There was no effect of treatment diet on nonoxidative phenylalanine disposal or phenylalanine release from protein breakdown. The developed methods are a valuable way to study protein metabolism and assess dietary amino acid adequacy in horses and will provide a useful tool for studying amino acid requirements in the future.
Publication Date: 2012-01-18 PubMed ID: 22259192DOI: 10.3945/jn.111.149906Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research study explores the effects of amino acid supplementation on protein metabolism and phenylalanine kinetics in Arabian geldings, a breed of horse, using stable isotope infusion methodologies. The findings suggest that the addition of supplemental amino acids to a standard diet does not impact whole-body phenylalanine kinetics.
Research Methodology
- The study builds upon stable isotope infusion methods, which were not previously used extensively in horses to study protein metabolism. It uses these methods to assess the impact of supplementary amino acids on whole-body phenylalanine kinetics in horses.
- Arabian geldings were infused with L-[1-(13)C] phenylalanine continuously for 6 hours, receiving either a control diet or adaptive diets supplemented with various equimolar amounts of glutamate, leucine, lysine, or phenylalanine. Blood and breath samples were collected every 30 minutes to measure phenylalanine kinetics.
Findings
- The research found that the plasma concentrations of the supplemented amino acids in those horses receiving leucine, lysine, and phenylalanine diets were significantly higher than those on the control diet.
- Isotopic equilibrium was reached in the horse’s blood phenylalanine and breath enrichments by 60 and 270 minutes, respectively.
- In horses receiving the phenylalanine treatment, phenylalanine flux and oxidation rates were significantly higher than those with the control diet. However, the research did not observe any effects of the treatment diets on nonoxidative phenylalanine disposal or phenylalanine release from protein breakdown.
Conclusion
- Despite the increase in plasma concentrations of supplemented amino acids in horses on adaptive diets, the study concludes that supplemental amino acids do not alter whole-body phenylalanine kinetics significantly.
- The methodologies developed in this study are emphasized as valuable tools for studying protein metabolism and assessing dietary amino acid adequacy in horses. The tools are stated to be useful for future studies on horses’ amino acid requirements.
Cite This Article
APA
Urschel KL, Geor RJ, Hanigan MD, Harris PA.
(2012).
Amino acid supplementation does not alter whole-body phenylalanine kinetics in Arabian geldings.
J Nutr, 142(3), 461-469.
https://doi.org/10.3945/jn.111.149906 Publication
Researcher Affiliations
- Department of Animal and Poultry Science, Virginia Tech, Blacksburg, VA, USA. klur222@uky.edu
MeSH Terms
- Amino Acids / administration & dosage
- Animal Nutritional Physiological Phenomena
- Animals
- Carbon Isotopes
- Dietary Supplements
- Glutamic Acid / administration & dosage
- Horses / blood
- Horses / metabolism
- Kinetics
- Leucine / administration & dosage
- Lysine / administration & dosage
- Male
- Nutritional Requirements
- Orchiectomy
- Phenylalanine / administration & dosage
- Phenylalanine / blood
- Phenylalanine / metabolism
Citations
This article has been cited 1 times.- Mok CH, Urschel KL. Amino acid requirements in horses. Asian-Australas J Anim Sci 2020 May;33(5):679-695.
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