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

From: Dietary manipulation: a sustainable way to mitigate methane emissions from ruminants

Substrate   Products ∆G (KJ)1 Reactions
VFA production
 C6H12O6 + 2H2O 2 C2H4O2 + 2 CO2 + 8H+   Acetate production
 C6H12O6 + 4H+ 2 C3H6O3 + 2 H2O   Propionate production
 C6H12O6 C4H8O4 + 2 CO2 + 4H+   Butyrate production
Reductive process
 CO2 + 4H2 CH4 + 2 H2O − 67.4 Methane production
 2 CO2 + 4H2 C2H4O2 + 2 H2O −8.8 Reductive acetogenesis
 SO42− + 4H2 + H+ HS + 4 H2O − 84.4 Sulfate reduction
 NO3 + 4H2 + 2H+ NH4 + 3 H2O − 371 Nitrate reduction
  1. 1under following rumen conditions: H2 = 162 pa; pH = 6.5; [H2O] = 50 M; [succinate2−] = 4 × 10− 6 M; [malate2−] = [β-hydroxybutyryl-CoA] = [butyryl-CoA] = 10− 6 M; [acetate] = 70 mM; [propionate] = 25 mM; [butyrate] = 15 mM; [lactate] = 1 mM; [NH4+] = 11 mM (20 mg/dL); [HS] = 0.14 mM. ∆G = free energy change indicates how energetically favourable it is i.e. the higher ∆G, the more energy utilization and negative ∆G indicates the energy release