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Effects of pH and fermentative substrate on ruminal metabolism of fatty acids during short-term in vitro incubation

Troegeler-Meynadier, Annabelle and Palagiano, Clara and Enjalbert, Francis Effects of pH and fermentative substrate on ruminal metabolism of fatty acids during short-term in vitro incubation. (2014) Journal of Animal Physiology and Animal Nutrition, 98 (4). 704-713. ISSN 0931-2439

(Document in English)

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Official URL: http://dx.doi.org/10.1111/jpn.12128


The ruminal biohydrogenation of c9,c12-18:2 can be affected by the fiber / starch ratio of the diet and the ruminal pH. The objectives of this study were to examine independently in vitro the effects of fermentation substrate (hay vs. corn starch) and buffer pH (6 vs. 7) on the biohydrogenation of c9,c12-18:2 carried out by grape seed oil, focusing on its t11 and t10 pathways, using 6h ruminal incubations. The experimental design was a 2 x 2 factorial arrangement. Fermentation substrate and pH affected the C18 fatty acid balance in incubated media, but few interactions were observed. Compared to starch, hay as the fermentation substrate favored the production of 18:0 (x 2.3), all trans-18:1 isomers (x 12.6) and CLA (x 6.1) except c9,t11-CLA, and the disappearance of unsaturated C18 fatty acids, but decreased the production of odd and branched-chain fatty acids. Compared to pH 6 buffer, pH 7 buffer resulted in higher c9,c12-18:2 disappearance and CLA production. For c9,t11-CLA, an interaction was noticed between the two factors, leading to the highest production in cultures incubated on hay with the 7 pH buffer. Compared to starch, hay as fermentation substrate favored the activity of t11 producers which are fibrolytic bacteria, and the production of t10 isomers, possibly due to the presence of potential t10 producers in hay. Low pH resulted in a decreased t11 isomers production and in a slightly increased t10 isomers production, probably due to a modulation of enzymatic or bacterial activity.

Item Type:Article
Additional Information:Thanks to Wiley editor. The original PDF of the article can be found at Journal of Animal Physiology and Animal Nutrition website : http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291439-0396
HAL Id:hal-01108642
Audience (journal):International peer-reviewed journal
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Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
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Deposited On:22 Jan 2015 15:56

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