Orally supplemented L-arginine impairs amino acid absorption depending on dose in horses.
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<0.05) plasma L-Arg and ornthine concentrations and decreased (P<0.05) lysine and methionine concentrations compared with the control group. At 1 h post feeding, L-Arg mares had lower (P<0.05) plasma concentrations of histidine, glutamic acid, proline, isoleucine, threonine, phenylalanine, leucine, valine, alanine, and taurine. In Experiment 2, L-Arg supplementation increased (P<0.05) arginine and ornithine concentrations compared with urea and control; there was no difference among other amino acids. These experiments indicate that L-Argis absorbed and, dependent on the dose, alters the absorption of other amino acids in mares.
Department of Animal Sciences, University of Florida, 2250 Shealy Drive, Gainesville 32608 dekelle@ufl.edu.
D E
DE
Kelley
Department of Animal Sciences, University of Florida, 2250 Shealy Drive, Gainesville 32608.
L K
LK
Warren
Department of Animal Sciences, University of Florida, 2250 Shealy Drive, Gainesville 32608.
C J
CJ
Mortensen
D065567:Absorption, Physiological / Q000187:drug effects*; D000284:Administration, Oral; D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006736:Horses / Q000378:metabolism*; D016018:Least-Squares Analysis; D013997:Time Factors; D014508:Urea / Q000097:blood
D000596:Amino Acids; D014508:Urea; D001120:Arginine
L-arginine; amino acid absorption; equine