Document Detail

Effects of pH and concentrations of linoleic and linolenic acids on extent and intermediates of ruminal biohydrogenation in vitro.
MedLine Citation:
PMID:  14740844     Owner:  NLM     Status:  MEDLINE    
Three experiments were conducted by in vitro incubations in ruminal fluid to investigate the effects of pH and amounts of linoleic and linolenic acids on the extent of their biohydrogenation, the proportions of conjugated linoleic acid (CLA) and trans-C18:1 as intermediates, and the ratio trans-10:trans-11 intermediates. The effects of pH and amount of linoleic acid were investigated in kinetic studies, and effects of the amount of linolenic acid were studied with 6-h incubations. With identical initial amounts of linoleic acid, its disappearance declined when the mean pH during incubation was under 6.0 compared with a mean pH over 6.5, and when the amount of linolenic acid increased from 10 to 180 mg/160-ml flask, suggesting an inhibition of the isomerization step of the biohydrogenation. Low pH decreased the ratio of trans-10:trans-11 intermediates. With initial amounts of linoleic acid increasing from 100 to 300 mg, the percentage of linoleic acid disappearance declined, but the amount that disappeared increased, without modification of the trans-10:trans-11 ratio, suggesting a maximal capacity of isomerization rather than an inhibition. Moreover, increasing initial linoleic acid resulted in high amounts of trans-C18:1 and an increase of C18:0 that was a linear function of time, suggesting a maximal capacity for the second reduction step of biohydrogenation. High amounts of initial linolenic acid did not affect the amounts of CLA, trans-C18:1, or the ratio trans-10:trans-11. Based on these experiments, a ruminal pH near neutrality with high amount of dietary linoleic acid should modulate the reactions of biohydrogenation in a way that supports CLA and trans-11C18:1 in the rumen.
A Troegeler-Meynadier; M C Nicot; C Bayourthe; R Moncoulon; F Enjalbert
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  86     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2004-01-26     Completed Date:  2004-03-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4054-63     Citation Subset:  IM    
Ecole Nationale Vétérinaire, Département Elevage and Produits, Laboratoire d'Alimentation, 31076 Toulouse Cedex, France.
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MeSH Terms
Hydrogen-Ion Concentration
Linoleic Acids / analysis*,  metabolism*
Linoleic Acids, Conjugated / analysis,  metabolism
Linolenic Acids / analysis*,  metabolism*
Rumen / metabolism*
Reg. No./Substance:
0/Linoleic Acids; 0/Linoleic Acids, Conjugated; 0/Linolenic Acids

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