title: Effect of fat source on duodenal flow of trans-C18:1 fatty acids and milk fat production in dairy cows.
abstract: The objective of the study was to determine the effects of dietary fat source on duodenal flow, apparent absorption, and milk fat incorporation of trans-C18:1 fatty acids. Four ruminally and duodenally cannulated multiparous Holsteins cows in mid to late lactation were fed a basal diet containing 36% corn silage, 24% alfalfa haylage, and 40% concentrate (dry matter basis). Diets contained 0% supplemental fat (control diet), 3.7% high oleic sunflower oil, 3.7% high linoleic sunflower oil, or 3.7% partially hydrogenated vegetable shortening; treatments were administered in a 4 x 4 Latin square design with 3-wk experimental periods. The flow of trans-C18:1 to the duodenum was higher for cows fed diets supplemented with fat than for cows fed the control diet (283 vs. 64 g/d). Incomplete biohydrogenation accounted for the increased flow of trans-C18:1 to the duodenum in cows fed diets containing high oleic and high linoleic sunflower oil. Increased flow of trans-C18:1 in cows fed the diet containing partially hydrogenated vegetable shortening most likely originated from the trans-C18:1 in the diet. Milk fat percentages were 3.48, 3.07, 3.18, and 3.38% for cows fed the control diet and diets containing high oleic sunflower oil, high linoleic sunflower oil, and vegetable shortening, respectively. Milk trans-C18:1 increased from 2.9 to 11.2% of the total fatty acids for cows fed the control diet and the diets supplemented with fat, respectively. Milk trans-C18:1 were equal across all diets supplemented with fat. Ruminal and total tract digestion of organic matter, neutral detergent fiber, and N did not change with fat supplementation. Results showed that trans-C18:1 is increased in the milk of cows with reduced milk fat; however, excessive amounts of trans-C18:1 in milk do not necessarily correspond directly to milk fat depression.
authors.affiliation: University of Maryland, College Park 20742, USA.
authors.forename: K F
authors.initials: KF
authors.lastname: Kalscheur
authors.forename: B B
authors.initials: BB
authors.lastname: Teter
authors.forename: L S
authors.initials: LS
authors.lastname: Piperova
authors.forename: R A
authors.initials: RA
authors.lastname: Erdman
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D004386:Duodenum / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D007774:Lactation; D008055:Lipids / Q000096:biosynthesis*; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D012417:Rumen / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids; D005232:Fatty Acids, Volatile; D008055:Lipids; D009584:Nitrogen