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Rates and efficiencies of reactions of ruminal biohydrogenation of linoleic acid according to pH and polyunsaturated fatty acids concentrations

Troegeler-Meynadier, Annabelle and Bret-Bennis, Lydie and Enjalbert, Francis Rates and efficiencies of reactions of ruminal biohydrogenation of linoleic acid according to pH and polyunsaturated fatty acids concentrations. (2006) Reproduction Nutrition Development, vol. 46 (n° 6). pp. 713-724. ISSN 0926-5287

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Official URL: http://dx.doi.org/10.1051/rnd:2006046

Abstract

Data from a previous study about the effects of pH and of linolenic acid (C18:3n-3) andlinoleic acid (C18:2n-6) concentrations on C18:2n-6 biohydrogenation in ruminal cultures were used to calculate the rates and efficiencies of the three reactions of C18:2n-6 biohydrogenation (isomerisation of C18:2n-6 to CLA; reduction of CLA to trans-octadecenoic acids; reduction of trans-octadecenoic acids to stearic acid). First, low pH was confirmed to inhibit isomerisation and was shown to inhibit the second reduction, leading to an accumulation of vaccenic acid. This later effect had only been observed in some in vivo studies using high concentrate diets, because in in vitro experiments, the very low pH frequently used depresses isomerisation which consequently generates very low amount of substrates for reductions whose variations become difficult to ascertain. Second, C18:2n-6 at high concentration was confirmed to saturate its own isomerisation and the increase of CLA production due to high initial C18:2n-6 was shown to inhibit the two subsequent reductions. Third, C18:3n-3 at high concentrations was confirmed to inhibit C18:2n-6 isomerisation. Moreover, the second reduction was shown to be saturated, probably by all trans-octadecenoic acids intermediates of C18:2n-6 and C18:3n-3 biohydrogenation, leading to an accumulation of trans-octadecenoic acids, especially vaccenic acid. This fatty acid is partly desaturated into CLA in the mammary gland, which explains the synergy between C18:2n-6 and C18:3n-3 for milk CLA noticed by others in vivo. This approach helped explain the actions of pH and of C18:2n-6 and C18:3n-3 concentrations on C18:2n-6 biohydrogenation and allows some explanations about differences noticed between studies.

Item Type:Article
Additional Information:The second PDF file is an erratum. Thanks to EDP Sciences editor. The definitive version is available at http://rnd.edpsciences.org/index.php?option=com_article&access=doi&doi=10.1051/rnd:2006046&Itemid=129
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Ecole Nationale Vétérinaire de Toulouse - ENVT
French research institutions > Institut National de la Recherche Agronomique - INRA
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Deposited By:Annabelle Troegeler

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