The production of acetate, propionate and butyrate in the rumen of sheep: Fitting models to 14C- or 13C-labelled tracer data to determine synthesis rates and interconversions

Abstract

A procedure is described for solving an open, fully exchanging, three-compartment model representing ruminal volatile fatty acids (VFA) kinetics in sheep. This model was solved using results from a published study in which labelled VFA, viz. 1-14C-acetate (Ac), 1-14C-propionate (Pr) and 1-14C-butyrate (Bu), were infused individually at a constant rate for 240 min into the rumen of sheep on different occasions. During the tracer infusions, the sheep were given 75 g of lucerne (Medicago sativa) every hour. The patterns of increasing specific radioactivity (SA) during the infusions were described by differential equations that were solved using the computer software, WinSAAM. This linear kineti..