98 Gut Microbiome: Implications on gut Health

Abstract

Abstract The rumen and the hindgut, which includes cecum and colon, of cattle are inhabited by a diverse microbial community, which is composed mainly of bacteria, but also includes archaea, protozoa, fungi and viruses. Most reside in the lumen, but also colonize the epithelial surface and their compositions are a critical component of the host health. Recent advances in sequencing techniques and biological computational tools have further underscored the complexity of the microbial community. The vast repertoire of the gut microbiome provides the host complementary genetic resources to harvest energy, provide proteins and vitamins, contribute to the development of gut epithelium and gut-associated lymphoid system, and to the overall gut health. The gut epithelium-vascular interface allows secretions, and absorption and metabolism of fermentation products and serves as a selective barrier to prevent translocation and systemic dissemination of microbes, microbial toxins, and immunogens. The barrier function includes protection form mechanical damage caused by feedstuffs, chemical damage from acidity, toxins and microbial invasion, especially pathogens. The mechanisms employed likely differ between the two fermentative regions of the gut, given the dramatic difference in epithelial structures. Rumen is lined by stratified squamous epithelium compared a single layer of columnar epithelium interspersed with mucus-producing goblet cells in the hindgut. The mucus layer is the first barrier the pathogen has to overcome for colonization and translocation. An imbalance in the composition of gut microbiota, called dysbiosis, leads to gut functional disorders. The dysbiosis can range from a change in one to a few species to the perturbation of entire microbial community. The assessment of gut microbial dysbiosis is a challenge because of the complexity and huge variations in the community composition, including animal-to-animal. The gut barrier function determines whether the dysbiotic changes are contained within the lumen or disseminated systemically to affect the health and productivity.