Table 1
Volatile fatty acids production (VFA) and reductive process in the rumen adopted from [95, 96]

SubstrateProducts∆G (KJ)1Reactions
VFA production
 C6H12O6 + 2H2O2 C2H4O2 + 2 CO2 + 8H+Acetate production
 C6H12O6 + 4H+2 C3H6O3 + 2 H2OPropionate production
 C6H12O6C4H8O4 + 2 CO2 + 4H+Butyrate production
Reductive process
 CO2 + 4H2CH4 + 2 H2O− 67.4Methane production
 2 CO2 + 4H2C2H4O2 + 2 H2O−8.8Reductive acetogenesis
 SO42− + 4H2 + H+HS + 4 H2O− 84.4Sulfate reduction
 NO3 + 4H2 + 2H+NH4 + 3 H2O− 371Nitrate reduction