Orally supplemented L-arginine impairs amino acid absorption depending on dose in horses

• Published in: Journal of animal science 2014-12, Vol.92 (12), p.5560-5566
• Main Authors: Kelley, D E, Warren, L K, Mortensen, C J
• Format: Article
• Language: English
• Subjects: Absorption, Physiological - drug effects; Administration, Oral; Amino Acids - blood; Amino Acids - metabolism; Animals; Arginine - administration & dosage; Arginine - blood; Arginine - pharmacology; Dietary Supplements; Dose-Response Relationship, Drug; Female; Horses - metabolism; Least-Squares Analysis; Time Factors; Urea - blood
• ISSN: 1525-3163
• DOI: 10.2527/jas.2014-7690

The beneficial effect of L-arginine (L-Arg) supplementation, on the physiology of several species, has generated an interest in the use of L-Arg as a nutraceutical in horses, but dosage and absorption of orally supplemented L-Arg must be inferred from other species. The study objective was to determine the effect of 2 oral L-Arg doses on plasma arginine concentrations and the effect on absorption of other amino acids in mares. In Experiment 1, mares were blocked by age and breed and were fed L-Arg supplemented (supplemented with 0.025% BW L-Arg; n=6) or control (no supplement; n=6) concentrate on a single day with blood samples taken at 0, 0.5, 1, 2, 3, 4, and 5 h relative to feeding. In Experiment 2, mares (n=6) were used in a 3×3 Latin square design with L-Arg (0.0125% of BW), urea (0.0087% of BW), and control (no supplement) fed mixed into a grain concentrate as single meal with blood samples taken at 0, 1,2, 4, 6, 8,10, and 12 h relative to feeding. In Experiment 1, L-Arg supplementation increased (P