In vitro incubations using bovine mammary post-mitochondrial supernatant were conducted using a stable isotope of acetate to measure de novo fatty acid synthesis. Incubations were done with and without enzyme inhibitors for acetyl CoA carboxylase and fatty acid synthase to determine the effects of partial inhibition on total enzyme activity on the fatty acids synthesized. There was no significant change in composition of fatty acids synthesized and the results of this experiment confirm that the use of enzyme inhibition in this pathway is suitable for experiments to apply metabolic control analysis.