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|Title:||Effect of Dietary Fiber on Endogenous Nitrogen Flows in Lactating Dairy Cows||Contributor(s):||Ouellet, D R (author); Demers, M (author); Zuur, G (author); Lobley, G E (author); Seoane, J R (author); Nolan, John Vivian (author) ; Lapierre, H (author)||Publication Date:||2002||Handle Link:||https://hdl.handle.net/1959.11/3858||Abstract:||The effect of dietary fiber on endogenous N secretion was studied using a ¹⁵N isotope dilution technique in four fistulated Holstein cows. Two isonitrogenous diets differing only in fiber (NDF and ADF) content were used in a crossover design. One diet (HF) contained 37.4% NDF, while the other (LF) contained 23.3%. A new model was developed to estimate endogenous N secretions and losses for the preintestinal, intestinal, and the total sections of the gastrointestinal tract. Three precursor pools: TCA-soluble fraction of plasma, intestinal mucosa, and milk were compared. Although endogenous losses estimated with the model were numerically different for each precursor pool selected (TCA-soluble fraction > mucosa > milk), treatment effects were similar. As intestinal mucosa is probably closest to the precursor pool, these data are discussed. Non-urea N endogenous secretions contributed 13% of the duodenal N flow but were not affected by the fiber content of the diet. The nonurea N endogenous flow at the duodenum was comprised of approximately equal inputs from endogenous N direct, and that incorporated into the microbial biomass. Total endogenous N flows at the duodenum exceeded, by nearly twofold, estimated inputs of urea-N to microbial biomass. Metabolic fecal output averaged 17% of fecal N and was not affected by level of dietary fiber, but net losses from secretions occurring in the small intestine were higher with the low fiber diet. Overall, endogenous N secretions represented 30% of total digestive tract protein synthesis.||Publication Type:||Journal Article||Source of Publication:||Journal of Dairy Science, 85(11), p. 3013-3025||Publisher:||Elsevier Inc||Place of Publication:||United States of America||ISSN:||1525-3198
|Field of Research (FOR):||070204 Animal Nutrition||Socio-Economic Outcome Codes:||830302 Dairy Cattle||Peer Reviewed:||Yes||HERDC Category Description:||C1 Refereed Article in a Scholarly Journal||Other Links:||http://jds.fass.org/cgi/reprint/85/11/3013.pdf
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