Adaptation of compartmental schemes for interpreting isotope dilution data on volatile fatty acid metabolism in the rumen to the non-steady state and for single-dose injection.

A unifying mathematical analysis of the one-pool and three-pool schemes for estimating acetate, propionate and butyrate production in the rumen from isotope dilution data is presented. Emphasis is given to non-steady-state conditions and to the administration of isotope as a single injection. The single-pool representation is also derived as a special case of the three-pool representation by assuming that the external fluxes are directly proportional to their concentrations in the rumen.