Microbial community profiles of the jejunum from steers differing in feed efficiency

Research regarding the association between the microbiome and host feed efficiency in cattle has primarily focused on the rumen. However, the various microbial populations within the gastrointestinal tract as a whole are critical to the overall well-being of the host and need to be examined when determining the interplay between host and non-host factors affecting feed efficiency. The objective of this study was to characterize the microbial communities of the jejunum among steers differing in feed efficiency. Within two contemporary groups of steers, individual feed intake (FI) and body weight (BW) gain were determined from animals fed the same ration. Within contemporary group, BW gain was regressed on FI and the four most extreme steers within each Cartesian quadrant were sampled (n=16/group). Bacterial 16S rRNA gene amplicons were sequenced from the jejunum content using next-generation sequencing technology. UniFrac principal coordinate analyses did not detect any separation of microbial communities within the jejunum, and no significant changes were indicated by bacterial diversity or richness metrics. The relative abundances of microbial populations and operational taxonomic units did reveal significant differences between feed efficiency groups. The phylum Firmicutes accounted for up to 90% of the populations within all jejunal groups, and was dominated by the families Clostridiaceae and Ruminococcaceae. Significant population shifts in taxa were detected, including the phylum Proteobacteria, families Lachnospiraceae, Coriobacteriaceae, and Sphingomonadaceae, and the genera Butyrivibrio, Acidaminococcus, and Ammoniphilus. This study suggests the association of the jejunum microbial community as a factor influencing feed efficiency at the 16S level.