title: Indicator amino acid oxidation responds rapidly to changes in lysine or protein intake in growing and adult pigs.
abstract: There is disagreement about the adaptation time required when using the indicator amino acid oxidation (IAAO) technique. Our objective was to establish the adaptation time required to obtain a plateau in indicator (L-[1-(14)C]-phenylalanine) oxidation in response to a test diet using growing and adult pigs. Four barrows (20 kg) and 4 sows (240 kg) were surgically implanted with venous catheters for isotope infusion. Growing Pigs: After 7 d of adaptation to an adequate lysine intake of 8.8 g/d, phenylalanine oxidation in growing pigs was 9.38 +/- 1.25% of the infused dose. At 2, 3, 4, or 6 d after reducing lysine intake to 3.8 g/d, and then increasing it back to 8.8 g/d, phenylalanine oxidation was 16.94 +/- 0.84% (P < 0.05) and 9.70 +/- 0.80% (P < 0.05), respectively, with no significant effect of days of adaptation to diet. Adult Pigs: After 14 d of adaptation to an intake of 200% of the amino acid maintenance requirement, phenylalanine oxidation in sows was 4.23 +/- 0.45% of dose. Changing the intake to 100 and 50% of the maintenance requirement, increased (P < 0.05) phenylalanine oxidation to 5.95 +/- 0.26 and 7.90 +/- 0.26%, respectively, with no significant effect of time (1, 2, 5, 6, 9, and 10 d) after diet change. The CV for repeated phenylalanine oxidation measurements within pigs and diets was 13.5% for growing and 8.8% for adult pigs. This demonstrates that the IAAO requires <2 d of adaptation regardless of age, dietary challenge (individual amino acid or total protein) or direction (increase or decrease) of change, and that the measured oxidation rate (% of dose) is highly repeatable.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5.
authors.forename: Soenke
authors.initials: S
authors.lastname: Moehn
authors.forename: Robert F P
authors.initials: RF
authors.lastname: Bertolo
authors.forename: Paul B
authors.initials: PB
authors.lastname: Pencharz
authors.forename: Ronald O
authors.initials: RO
authors.lastname: Ball
mesh_terms: D000222:Adaptation, Physiological; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D008239:Lysine / Q000008:administration & dosage*; D008297:Male; D009919:Orchiectomy; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000378:metabolism; D015203:Reproducibility of Results; D013552:Swine / Q000254:growth & development* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; D004044:Dietary Proteins; D010649:Phenylalanine; D008239:Lysine