Taxonomic and functional characterization of the rumen microbiome of Japanese Black cattle revealed by 16S rRNA gene amplicon and metagenome shotgun sequencing.

This study aimed to determine the taxonomic and functional characteristics of the Japanese Black steer rumen microbiome. The rumen microbiomes of six Japanese Black steers (age 14.7 ± 1.44 mo) and six Japanese Black sires × Holstein dams crossbred (F1) steers (age 11.1 ± 0.39 mo), fed the same diet, were evaluated. Based on 16S rRNA gene sequencing, the beta diversity revealed differences in microbial community structures between the Japanese Black and F1 rumen. Shotgun sequencing showed that Fibrobacter succinogenes and two Ruminococcus spp., which are related to cellulose degradation were relatively more abundant in the Japanese Black steer rumen than in the F1 rumen. Furthermore, the 16S rRNA gene copy number of F. succinogenes was significantly higher in the Japanese Black steer rumen than in the F1 rumen according to quantitative real-time polymerase chain reaction analysis. Genes encoding the enzymes that accelerate cellulose degradation and those associated with hemicellulose degradation were enriched in the Japanese Black steer rumen. Although Prevotella spp. were predominant both in the Japanese Black and F1 rumen, the genes encoding carbohydrate-active enzymes of Prevotella spp. may differ between Japanese Black and F1.