PSXIV-23 Characterization of microbial communities associated with the rumen lining, digesta and rumen fluid from beef cattle consuming a high energy diet using 16S rRNA gene amplicon sequencing

Abstract

Abstract The true etiology of liver abscesses is not well known. Therefore, the objective of this study was to characterize the microbial communities in the rumen lining, digesta, and rumen fluid from beef cattle consuming a high energy diet, using 16S rRNA gene amplicon sequencing. Twelve crossbred feedlot steers (450 ±10 kg; ~ 3.0 years of age) fitted with ruminal fistulas, consuming a high energy finishing diet (1.43 NEg, Mcal/kg DM) for 21 d were utilized in this experiment. Microbial DNA from three regions within the rumen [rumen lining (ventral/lateral), digesta (geometric center of the rumen), and rumen fluid] was extracted and the V4 region of the 16S rRNA gene was amplified and sequenced. Across all sample regions, bacterial sequences were classified into 34 phyla, 76 classes, 143 orders, and 254 families. Bacteroidetes and Firmicutes were the predominant phyla present across all samples. The relative abundance of Bacteroidetes detected in rumen fluid was lesser (P < 0.05) when compared to bacteria sampled from the rumen lining and digesta. In contrast, the relative abundance of Firmicutes were greater (P < 0.05) in rumen fluid and the rumen lining when compared to digesta samples. There are very few publications describing the complex community of the rumen microbiome. To our knowledge this is the first publication categorizing microbial populations in three distinct locations within the rumen using next generation sequencing in feedlot cattle.