APPLICATION OF A MECHANISTIC MODEL OF BOVINE-MILK PROTEIN-SYNTHESIS TO EXAMINE THE USE OF ISOTOPE LABELING METHODS

Two types of models of bovine milk protein synthesis were used to simu late collection and analysis of data from infusion experiments involvi ng isotope-labeled amino acids (AA). Analytical solutions to a system of ordinary differential equations that describe isotope enrichment cu rves of each AA pool within the mammary gland were derived and are pre sented. Numerical solutions from a dynamic mechanistic model suggest t hat normal experimental procedures can affect the shape of enrichment curves and, therefore, results derived from them. Simulation results s uggest that standard methods utilizing in vivo isotope kinetics may be of limited value to characterize the metabolism of the bovine mammary gland, especially AA metabolism and milk protein synthesis and secret ion. The results clearly demonstrate the flexibility of such models fo r the testing of many hypotheses and possible experimental protocols.