| Nitrogen transactions along the gastrointestinal tract of cattle: A meta-analytical approach. | |
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MedLine Citation:
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PMID: 18073282 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In ruminant animals, endogenous N (EN) secretions contribute to meeting the N requirement of the ruminal microflora. The EN also constitutes a sizable portion of the duodenal N flow, which might be available to the host animal. Most measures of EN have been accomplished with highly invasive techniques or unusual semisynthetic diets. By utilizing a statistical approach and data obtained from studies reporting duodenal, ileal, and fecal N flows in cattle, the EN losses and true digestibility of N were estimated for different segments of the gastrointestinal tract of cattle. A simulation for a reference diet (24.2 g of N/kg of OM, 32% NDF and carbohydrates of medium fermentation rate) consumed at 2% of BW daily estimated that the minimal contribution of EN to the N available in the rumen was 39%. The free EN represented 13% of the duodenal N flow, and when bacterial N of EN origin was considered, EN contributed 35% of the total N flow. The minimal entry of EN into various segments of the gastrointestinal tract was also estimated as: foregut, 10.54; small intestine, 3.10; and hindgut, 5.0 g/kg of OMI. Rumen dietary N degradability was 0.68, and true N digestibilities in the small intestine and hindgut were 0.75 and 0.49, respectively. A better understanding of the factors involved in EN losses will allow for a more accurate estimation of both N supply and N requirements. This will translate into improved accuracy of diet formulation and less N excreted into the environment. |
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Authors:
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J C Marini; D G Fox; M R Murphy |
Publication Detail:
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Type: Journal Article; Meta-Analysis; Research Support, U.S. Gov't, Non-P.H.S. Date: 2007-12-11 |
Journal Detail:
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Title: Journal of animal science Volume: 86 ISSN: 1525-3163 ISO Abbreviation: J. Anim. Sci. Publication Date: 2008 Mar |
Date Detail:
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Created Date: 2008-02-20 Completed Date: 2008-11-03 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8003002 Medline TA: J Anim Sci Country: United States |
Other Details:
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Languages: eng Pagination: 660-79 Citation Subset: IM |
Affiliation:
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US Department of Agriculture/ARS Children's Nutrition Research Center, Houston 77030, USA. marini@bcm.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Bacteria / chemistry, growth & development Cattle / metabolism* Diet / veterinary Digestion / physiology* Female Gastrointestinal Tract / metabolism*, microbiology Male Models, Biological Nitrogen / metabolism* Regression Analysis |
| Chemical | |
Reg. No./Substance:
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7727-37-9/Nitrogen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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