title: Ruminal synthesis, biohydrogenation, and digestibility of fatty acids by dairy cows.
abstract: Ruminal synthesis and biohydrogenation of fatty acids in dairy cows were determined by sampling duodenal digesta through T-cannulas. Fatty acid digestibility in the total tract also was measured. Five diets (concentrate:alfalfa hay:alfalfa haylage:corn silage, 2:1:1:1, DM) in a 5 x 5 Latin square contained either no added fat; 3 or 6% added calcium soap; or 3 or 6% animal-vegetable blend fat. Seventy percent of dietary fatty acids were recovered at the duodenum, and 106 g/d were synthesized in the rumen regardless of diets. Fatty acids synthesized in greatest amounts were odd or branched chains, whereas more than 90% of the fatty acids shorter than 14 carbons disappeared. Fatty acids in calcium soap were biohydrogenated 57% and in animal-vegetable blend 87%. Fatty acids in calcium soap were more digestible (80.0 vs. 75.7%) than those in the blended fat due to greater unsaturation in the small intestine. Ruminal microorganisms selectively synthesized fatty acids.
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: O A
authors.initials: OA
authors.lastname: Ohajuruka
authors.forename: D L
authors.initials: DL
authors.lastname: Palmquist
mesh_terms: D000821:Animal Feed; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D002417:Cattle / Q000502:physiology*; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D004063:Digestion; D005227:Fatty Acids / Q000008:administration & dosage / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D005285:Fermentation; D006865:Hydrogenation; D007422:Intestines / Q000502:physiology; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids