title: Relationships among milk urea-nitrogen, dietary parameters, and fecal nitrogen in commercial dairy herds.
abstract: Our study objective was to determine the ability of milk urea-nitrogen concentrations ([MUN]) to predict fecal nitrogen concentrations ([Fecal N]) in commercial dairy herds. A total of 83 dairy herds were each visited 3 times within 48 h after a monthly herd milk test. For each farm visit, forages were sampled for nutrient analyses, which were entered into a computerized ration evaluator, and fecal samples were taken per rectum from each of 6 cows (2 early-, 2 mid-, and 2 late-lactation). Fecal samples were pooled, mixed, and analyzed for nitrogen content. Fecal nitrogen concentrations were compared with the routinely measured nutritional parameters from the ration evaluation, and the herd average [MUN] for the previous milk test date using mixed linear regression analyses. Total protein supplied in the ration was significantly positively associated with [Fecal N], but herd average [MUN] was not associated (P > 0.10) with [Fecal N].
authors.affiliation: Department of Large Animals and Wildlife Clinical Science, Faculty of Veterinary Medicine, Kasetsart University, Kamphaengsaen, Thailand.
authors.forename: Pipat
authors.initials: P
authors.lastname: Arunvipas
authors.forename: John A
authors.initials: JA
authors.lastname: VanLeeuwen
authors.forename: Ian R
authors.initials: IR
authors.lastname: Dohoo
authors.forename: Greg P
authors.initials: GP
authors.lastname: Keefe
authors.forename: Shelley A
authors.initials: SA
authors.lastname: Burton
authors.forename: Kerry D
authors.initials: KD
authors.lastname: Lissemore
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D005243:Feces / Q000737:chemistry*; D005260:Female; D007774:Lactation / Q000378:metabolism; D016014:Linear Models; D008892:Milk / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis*; D014508:Urea / Q000032:analysis*
chemical_list: D004044:Dietary Proteins; D014508:Urea; D009584:Nitrogen