Document Detail

A model of net amino acid absorption and utilization by the portal-drained viscera of the lactating dairy cow.
MedLine Citation:
PMID:  15545389     Owner:  NLM     Status:  MEDLINE    
A more complete understanding of amino acid (AA) metabolism by the various tissues of the body is required to improve upon current systems for predicting the use of absorbed AA. The objective of this work was to construct and parameterize a model of net removal of AA by the portal-drained viscera (PDV). Six cows were prepared with arterial, portal, and hepatic catheters and infused abomasally with 0, 200, 400, or 600 g of casein daily. Casein infusion increased milk yield quadratically and tended to increase milk protein yield quadratically. Arterial concentrations of a number of essential AA increased linearly with respect to infusion amount. When infused casein was assumed to have a true digestion coefficient of 0.95, the minimum likely true digestion coefficient for noninfused duodenal protein was found to be 0.80. Net PDV use of AA appeared to be linearly related to total supply (arterial plus absorption), and extraction percentages ranged from 0.5 to 7.25% for essential AA. Prediction errors for portal vein AA concentrations ranged from 4 to 9% of the observed mean concentrations. Removal of AA by PDV represented approximately 33% of total postabsorptive catabolic use, including use during absorption but excluding use for milk protein synthesis, and was apparently adequate to support endogenous N losses in feces of 18.4 g/d. As 69% of this use was from arterial blood, increased PDV catabolism of AA in part represents increased absorption of AA in excess of amounts required by other body tissues. Based on the present model, increased anabolic use of AA in the mammary and other tissues would reduce the catabolic use of AA by the PDV.
M D Hanigan; C K Reynolds; D J Humphries; B Lupoli; J D Sutton
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of dairy science     Volume:  87     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2004 Dec 
Date Detail:
Created Date:  2004-11-16     Completed Date:  2005-04-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4247-68     Citation Subset:  IM    
Land O' Lakes, Inc., Gray Summit, MO 63039, USA.
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MeSH Terms
Caseins / blood,  metabolism,  pharmacokinetics*
Cattle / physiology*
Dose-Response Relationship, Drug
Feces / chemistry
Intestinal Absorption / drug effects
Lactation / metabolism*,  physiology
Milk / chemistry,  drug effects,  secretion*
Milk Proteins / analysis,  metabolism
Models, Biological
Portal System
Portal Vein / metabolism
Splanchnic Circulation
Viscera / blood supply,  metabolism*
Reg. No./Substance:
0/Caseins; 0/Milk Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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