HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-674v1 85/10/2556    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ungerfeld, E. M. Articles by Newbold, C. J. Search for Related Content PubMed PubMed Citation Articles by Ungerfeld, E. M. Articles by Newbold, C. J.

A meta-analysis of fumarate effects on methane production in ruminal batch cultures

E. M. Ungerfeld^*, R. A. Kohn^*,1, R. J. Wallace and C. J. Newbold

^* Department of Animal and Avian Sciences, University of Maryland, College Park 20742; and Microbial Biochemistry Group, Gut Health Programme, Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB, Scotland, UK^,2; and and Department of Rural Sciences, The University of Wales, Aberystwyth SY23 2AX, Ceredigion, UK

¹ Corresponding author: rkohn{at}umd.edu

The objective of this study was to understand the effects of fumarate addition on methane (CH₄) and VFA production in the rumen through a meta-analysis of its effects on ruminal batch cultures. Because the reduction of fumarate to succinate can draw electrons away from ruminal methanogenesis, fumarate has been studied as a potential feed additive to decrease CH₄ production in ruminants. The average decrease in CH₄ in batch cultures was of 0.037 µmol/ µmol of added fumarate, which is considerably lower than 0.25 µmol/µmol, the decrease predicted from the stoichiometry of the reactions involved. One reason that fumarate was not effective at decreasing CH₄ in batch cultures was that only an average of 48% of added fumarate appeared to be converted to propionate. Secondly, the incorporation of reducing equivalents in the conversion of fumarate to propionate was almost entirely offset by their release from an average of 20% of added fumarate that appeared to be converted to acetate. Thermodynamic calculations indicated that the conversion of added fumarate to both propionate and acetate was feasible. Fumarate appears to be more effective in decreasing CH₄ production and increasing propionate in continuous culture than in batch culture. This suggests that microbial adaptation to fumarate metabolism can be important. Variation in populations of fumarate-reducers, methanogens, and protozoa could all be involved. Fumarate supplementation for an extended period may result in the amplification of otherwise small populations of fumarate-reducers. Addition of some of these organisms may be helpful to improve fumarate conversion to propionate. Strategies based on enhancing the rumen’s capacity to convert fumarate to propionate by maintaining a low fumarate concentration have been effective. Thermodynamic considerations should be taken into account when designing strategies for CH₄ abatement through the addition of external electron acceptors.

Key Words: fermentation • fumarate • meta-analysis • methane • rumen