title: Postruminal synthesis modifies the odd- and branched-chain fatty acid profile from the duodenum to milk.
abstract: Milk odd- and branched-chain fatty acids (OBCFA) have been suggested as potential biomarkers for rumen function. The potential of milk OBCFA as a biomarker depends on whether their profile reflects the profile observed in the duodenum. The objective of this study was to evaluate whether the OBCFA profile in duodenum samples is reflected in plasma and milk. For this, 2 dairy cattle experiments were used. In experiment 1, 4 Holstein cows fitted with rumen and proximal duodenum cannulas were used in a 4×4 Latin square design. The treatments consisted of 2 nitrogen levels (143 vs. 110g of crude protein/kg of dry matter for high and low N, respectively) combined with either 1 of the 2 energy sources (i.e., starch from barley, corn, and wheat or fiber from soybean hulls and dehydrated beet pulp). In experiment 2, 4 Holstein cows fitted with rumen and proximal duodenum cannulas were used in a 3×3 Latin square design, with the treatments consisting of 3 diets: (1) RNB-, a diet with a crude protein content of 122g/kg of dry matter, predicted to provide protein digested in the small intestine according to the requirement of the animals, but with a shortage of rumen degradable protein; (2) RNB- to which 6g/d of niacin was added through inclusion in the mineral and vitamin premix, and (3) RNB- to which urea was added to balance rumen degradable N supply resulting in a CP content of 156g/kg of dry matter. In both experiments, samples of duodenal digesta, plasma, and milk were collected and analyzed for fatty acids. Additionally, lipids in plasma samples were separated in lipid classes and analyzed for fatty acids. The OBCFA profile in milk was enriched in 15:0, iso-17:0, anteiso-17:0, and cis-9-17:1 as compared with duodenal samples, and milk secretions even exceeded duodenal flows, which suggests occurrence of postruminal synthesis, such as de novo synthesis, desaturation, and elongation. The postruminal modification of the OBCFA profile might hamper the application of OBCFA as diagnostic tools of rumen function.
authors.affiliation: Laboratory for Animal Nutrition and Animal Product Quality, Faculty of Bioscience Engineering, Ghent University, Proefhoevestraat 10, 9090 Melle, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Vlaeminck
authors.affiliation: Département des Sciences Animales, Université Laval, 2425 rue de l'Agriculture, Québec, Québec G1V 0A6, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Gervais
authors.affiliation: Laboratory for Animal Nutrition and Animal Product Quality, Faculty of Bioscience Engineering, Ghent University, Proefhoevestraat 10, 9090 Melle, Belgium.
authors.forename: M M
authors.initials: MM
authors.lastname: Rahman
authors.affiliation: Laboratory for Animal Nutrition and Animal Product Quality, Faculty of Bioscience Engineering, Ghent University, Proefhoevestraat 10, 9090 Melle, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Gadeyne
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Gorniak
authors.affiliation: INRA/Vet Agro Sup, UMR1213 Herbivore Research Unit, 63122 Saint-Genès Champanelle, France.
authors.forename: M
authors.initials: M
authors.lastname: Doreau
authors.affiliation: Laboratory for Animal Nutrition and Animal Product Quality, Faculty of Bioscience Engineering, Ghent University, Proefhoevestraat 10, 9090 Melle, Belgium. Electronic address: Veerle.Fievez@UGent.be.
authors.forename: V
authors.initials: V
authors.lastname: Fievez
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena / Q000187:drug effects; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D005227:Fatty Acids / Q000097:blood / Q000378:metabolism*; D005260:Female; D008892:Milk / Q000737:chemistry* / Q000187:drug effects; D009584:Nitrogen / Q000008:administration & dosage / Q000378:metabolism*; D012417:Rumen / Q000187:drug effects / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D005227:Fatty Acids; D009584:Nitrogen
keywords: blood lipids; bovine; elongation; endogenous fatty acid synthesis; microbial fatty acids