Rumen DNA virome in beef cattle reveals an unexplored diverse community with potential links to carcass traits.

Rumen deoxyribonucleic acid viruses that infect and replicate within bacteria and archaea are key modulators of the prokaryotic community. These viruses influence prokaryotic community abundance, composition, and function impacting host productivity and methane production. In this study, viral genomes were assembled from the rumen of 37 Japanese Black cattle using virus-like particle metagenome sequencing, providing insights into viral diversity, functional potential, and virus-host interactions. The relationship between the rumen deoxyribonucleic acid virome and carcass traits, particularly carcass weight and marbling, was also investigated. A total of 22 942 viral operational taxonomic units of medium-quality or higher (≥5 kb length and ≥ 50% completeness), referred to as Japanese Black Rumen Viral genomes, were reconstructed. Among these, 5973 putative novel genera were identified, significantly expanding the catalog of rumen viral genomes. Hosts were predicted for 2364 viral operational taxonomic units, including carbohydrate-degrading bacteria and methanogens. Additionally, 27 auxiliary metabolic genes were categorized as glycosyl hydrolases which are responsible for the degradation of cellulose, hemicellulose, and oligosaccharides, suggesting that rumen viruses may enhance the breakdown of complex carbohydrates during infection. Furthermore, the rumen virome differed considerably between high vs low carcass weight cattle and high vs low marbling cattle. Viruses associated with were linked to higher carcass weight. This database and the insights from this study provide primary information for the development and improvement of beef production.