title: Synthesis and biohydrogenation of fatty acids by ruminal microorganisms in vitro.
abstract: Ruminal degradation, synthesis, and biohydrogenation of fatty acids were examined in vitro. Diets were incubated with ruminal contents, and changes of fatty acids were measured. Two fat supplements, a calcium soap and an animal-vegetable blend, were included in diets at various levels. Addition to diets of acetate and isoacids (collective term for certain short-chain acids) also were tested for effects on fatty acid synthesis. Overall, 6.6 mg of fatty acids/g of fat-free diet were synthesized during 24-h incubation regardless of supplementations. Fatty acids synthesized in greatest amounts were odd-numbered or branched chains, whereas chains of 16 and 18 carbons changed little, and chains shorter than 14 carbons decreased. Degradation of [1-14C]palmitic acid was negligible, as determined by recovery of the label in CO2 (.03%) and acetate (1.09%) after 4-h incubation with rumen contents. Biohydrogenation of fatty acids averaged 47% in diets containing calcium soap and 71% with animal-vegetable blend. Synthesis and biohydrogenation were similar to those measured previously in vivo, showing that in vitro measurements reliably predicted metabolism of fatty acids in vivo.
authors.affiliation: Department of Dairy Science, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691.
authors.forename: Z
authors.initials: Z
authors.lastname: Wu
authors.forename: D L
authors.initials: DL
authors.lastname: Palmquist
mesh_terms: D000821:Animal Feed; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D005227:Fatty Acids / Q000096:biosynthesis / Q000378:metabolism*; D005766:Gastrointestinal Contents / Q000382:microbiology*; D006865:Hydrogenation; D066298:In Vitro Techniques; D012417:Rumen / Q000378:metabolism / Q000382:microbiology*
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids