Characterization of the Octadecenoic Acids in Rumen Digesta and Rumen Bacteria

Abstract

Analysis of the lipids from total rumen digesta with respect to time after feeding did not reveal any changes in total lipid, fatty acids, or the concentration of trans-octadecenoic acids. The octadecenoic acids from the rumen digesta consisted of 75% trans acids, trans-11-octadecenoic acid being the major acid. The rumen bacterial octadecenoic acids consisted of a mixture of 24 geometrical and positional isomers, the major acids being trans-11, cis-9, and cis-11-octadecenoic acids. The analyses indicated that the rumen bacteria preferentially esterify the cis isomer into polar lipid.