The relative abundance of Crenarchaeota at the phylum level, Thaumarchaeota and PBS-25 at the class level, Nitrososphaerales, SBR1031 and PBS-25 (Class) at the order level, Nitrososphaeraceae, Sphingomonadaceae, *Lactobacillales (Other),
Nitrospiraceae and SJA-101 at the family level, Candidatus Nitrososphaera, *Flavobacteriaceae (Family), *SJA101 (Family), *Rhizobiaceae (Family), *Hyphomonadaceae (Family), and Nitrosopumilus at the genus level had extremely significantly negative relationship with NDF digestibility (p< 0.01).