Table 6.

Eigenvalues obtained by principal component analysis describing the contribution to components 1, 2, and 3 of rumen fermentation variables affected by methanogenesis inhibitors using a rumen simulation technique.

Item	Component 1 (50.35%)	Component 2 (18.36%)	Component 3 (14.89%)
Dissolved hydrogen (μM)	0.019	0.249	−0.263
Total gas production (mL/d)	0.182	−0.105	0.222
Methane (%)A	0.162	−0.180	0.356
Gaseous hydrogen (%)A	0.204	0.098	−0.361
Carbon dioxide (%)A	−0.282	0.098	−0.083
Nitrous oxide (%)A	−0.239	0.152	0.083
OM disappearance (%)	0.152	0.352	0.110
EMPS (g microbial N/kg OM fermented)	−0.255	0.095	0.083
Total VFA (mM)	0.228	0.199	0.284
Acetate (mM)	−0.074	0.254	0.451
Propionate (mM)	0.200	0.354	0.138
Isobutyrate (mM)	0.270	0.158	0.145
Butyrate (mM)	0.268	0.209	0.096
Valerate (mM)	0.264	0.202	−0.142
Isovalerate (mM)	0.281	−0.051	0.143
Caproate (mM)	0.245	−0.256	−0.062
Heptanoate (mM)	0.245	−0.256	−0.062
Ethanol (mM)	−0.195	0.337	−0.138
Ammonium (mM)	0.259	−0.055	−0.199
Formate (mM)	0.205	−0.075	−0.251
n-propanol (mM)	0.127	0.353	−0.298

OM, organic matter; E_MPS, efficiency of microbial protein synthesis; N, nitrogen; VFA, volatile fatty acid.

^AGas percentages are based on the sum of CH₄, H₂, CO₂, and N₂O produced.