In the present study, the diversity of rumen methanogens in crossbred Karan Fries cattle was determined by
constructing 16S rRNA and mcrA (methyl coenzyme-M reductase α subunit) gene libraries using specific
primers. All thirteen OTUs or phylotypes from 16S rRNA library clustered with order Methanobacteriales, twelve
of which aligned with Methanobrevibacter spp., whereas one OTU resemble with Methanosphaera stadtmanae.
Out of eighteen OTUs identified from mcrA gene library, fifteen clustered with order Methanobacteriales, two
resemble with Methanomicrobiales and remaining one grouped with Methanosarcinales. These results revealed
thatMethanobrevibacter phylotypewas predominantly present in Karan Fries crossbred cattle fed on high fibrous
diet containing wheat straw. Compared to 16S rRNA gene, mcrA gene OTUs clustered in three orders providing
better insights of rumen methanogens diversity in cattle.