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Publication type: Journal Article
Document type: Full Paper

Year: 2006

Author(s): Hackl, S; van den Hoven, R; Zickl, M; Spona, J; Zentek, J

Title: Individual differences and repeatability of post-prandial changes of plasma-free amino acids in young horses.

Source: J Vet Med A Physiol Pathol Clin Med. 2006; 53(9):439-444

Authors Vetmeduni Vienna:

Van Den Hoven Rene
Zentek J├╝rgen

Vetmed Research Units
Clinical Unit of Equine Internal Medicine
Institute of Animal Nutrition and Functional Plant Compounds

Few data are available on post-prandial changes of plasma amino acids (AAs) in horses and on the repeatability and the individual variance on different sampling days. The objective of the present study was to measure pre- and post-prandial concentrations of plasma AA in 10 yearling horses. Blood samples were taken on days 1 and 40 of the study before feeding of hay, oats and soya meal and over an 8 h post-prandial period in 2-h intervals. The plasma AAs were measured by high-pressure liquid chromatography after ortho-phthalaldehyde derivatization. Mean fasting concentrations of the AAs were not significantly influenced by the individuum and sampling day. Repeatability of the fasting AA levels in the individual horses on two different sampling days was only found for histidine, 3-methylhistidine, methionine, tryptophan and taurine. While the absolute post-prandial AA concentrations differed between sampling days, the relative changes were comparable. All AA concentrations except 3-methylhistidine increased after feeding by 13% to more than 200% of their fasting values if the combined data of both days were analysed. Four hours after feeding the concentrations of arginine, asparagine, lysine, leucine, isoleucine and threonine, decreased more than 20%. Histidine, methionine, phenylalanine, valine, tryptophan, glutamine, glycine, tyrosine and taurine concentrations decreased by less than 20%. Concentrations of aspartic acid, glutamic acid, ornithine, serine and citrulline remained elevated. Most AA approached the fasting concentrations at 8 h, only glycine increased between 6 and 8 h after meal and 3-methyl-histidine concentrations were constant throughout the entire period. In conclusion, the pre-prandial plasma AA in horses appeared less influenced by individuum or sampling day than post-prandial plasma AA concentrations. Therefore, plasma AA concentrations should be interpreted only under well-defined conditions, especially regarding the feeding regimen.

Keywords Pubmed: Amino Acids/blood*
Area Under Curve
Chromatography, High Pressure Liquid/veterinary
Cross-Over Studies
Postprandial Period/physiology
Reference Values

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