Production and Utilization of Methane Biogas as Renewable Fuel

Rumen Microbiology: From Evolution to Revolution

“…Addition of organic acids to ruminal mixed cultures increased VFA production in many in vitro studies (Carro and Ranilla 2003a , b ;Giraldo et al 2007 ;Yu et al 2010 ). Both malate and fumarate are intermediates in the randomizing pathway of propionate production ( Fig.…”

“…Both malate and fumarate are intermediates in the randomizing pathway of propionate production ( Fig. Therefore, fumarate and malate can decrease the acetate-to-propionate ratio and increase the supply of propionate to the host animal (Mao et al 2007 ;Li et al 2009b ;Yu et al 2010 ). Therefore, fumarate and malate can decrease the acetate-to-propionate ratio and increase the supply of propionate to the host animal (Mao et al 2007 ;Li et al 2009b ;Yu et al 2010 ).…”

“…This was confi rmed for bermudagrass but not for alfalfa hay (Martin 2004 ). Supplementing mixed batch cultures with sodium fumarate, Mao et al ( 2007 ) found an increase in DM digestibility of roughage substrates, and Yu et al ( 2010 ) observed an increase in neutral detergent fi ber digestibility, with concomitant increases in endoglucanase and xylanase activities. Supplementing mixed batch cultures with sodium fumarate, Mao et al ( 2007 ) found an increase in DM digestibility of roughage substrates, and Yu et al ( 2010 ) observed an increase in neutral detergent fi ber digestibility, with concomitant increases in endoglucanase and xylanase activities.…”

“…Fumarate supplementation has sometimes decreased NH 4 + concentration (Bayaru et al 2001 ;Li et al 2009b ;Yu et al 2010 ;Zhou et al 2012 ), which might be related to an increased incorporation of NH 4 + into microbial amino acids but also to less deamination, which agrees with observation of diminished branched-chain VFA concentration with fumarate supplementation (Yu et al 2010 ). Lower NH 4 + and branched-chain VFA concentrations in the rumen of cattle supplemented with fumaric acid were also observed by Bayaru et al ( 2001 ).…”

“…Effects of fumarate on NH 4 + are not consistent though, and in other in vitro (López et al 1999 ;Carro and Ranilla 2003a ;Newbold et al 2005 ;Giraldo et al 2007 ;Mao et al 2008 ) and in vivo (Beauchemin and McGinn 2006 ) studies, no effects of fumarate on NH 4 + have been found. Contradictory results were interpreted by Yu et al ( 2010 ) as related to the proportion of concentrates in the diet. High-concentrate diets are associated with greater NH 4 + incorporation into carbon chains and less deamination, which would make the effect of fumarate on NH 4 + less apparent (Yu et al 2010 ).…”