title: Identification of cobalamin and cobalamin analogues along the gastrointestinal tract of dairy cows.
abstract: Cobalamin analogues in samples of rumen fluid, duodenal and ileal digesta and faeces of lactating dairy cows collected during the course of two nutritional studies were identified using a recently developed liquid chromatography-mass spectrometry method in order to determine if changes in diet composition could alter their proportions. Only cobalamin and cobinamine were detected in feedstuffs; six supplementary analogues were detected in the gastrointestinal tract content. The proportion of analogues produced by the gastrointestinal microflora was higher than the vitamin itself. The mode of conservation of forage had no effect on the proportion of analogues in rumen fluid, duodenal digesta and faeces, whereas increasing metabolisable protein supply raised the proportion of analogues reaching the duodenum (p = 0.008). The proportion of analogues was higher in ileal than duodenal digesta, this observation probably indicates a preferential absorption of cobalamin in the small intestine. The present results showed that changes in diet composition could alter cobalamin synthesis in rumen.
authors.affiliation: a Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada , Sherbrooke , QC , Canada.
authors.forename: Christiane L
authors.initials: CL
authors.lastname: Girard
authors.affiliation: a Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada , Sherbrooke , QC , Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Berthiaume
authors.affiliation: b Division of Hematology , University of Colorado Denver and Health Sciences , Aurora , Colorado , USA.
authors.forename: Sally P
authors.initials: SP
authors.lastname: Stabler
authors.affiliation: b Division of Hematology , University of Colorado Denver and Health Sciences , Aurora , Colorado , USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Allen
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D002853:Chromatography, Liquid / Q000662:veterinary; D004032:Diet / Q000662:veterinary; D004386:Duodenum / Q000737:chemistry; D005243:Feces / Q000737:chemistry; D005260:Female; D005766:Gastrointestinal Contents / Q000737:chemistry*; D007082:Ileum / Q000737:chemistry; D007774:Lactation; D013058:Mass Spectrometry / Q000662:veterinary; D012417:Rumen / Q000737:chemistry; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000378:metabolism*
chemical_list: D014805:Vitamin B 12
keywords: analogues; dairy cows; digestive tract; vitamin B12