Getting to the guts of food animal health

Studies with germ-free animals have clearly demonstrated the importance of microorganisms for proper development of a fully functional immune system and to influence an array of host physiological processes. Similarly, work with gnotobiotic animals shows that microbial colonization recapitulates host immune and physiological features, the degree to which is often dependent on the specific microbe(s), or the complexity of the microbial consortia administered. Therefore, the importance of microbial exposure for host development has been well established. Generally, the host is considered to be initially exposed to commensal microbes during the birthing or hatching process. However, recent data propose the possibility of in-utero or in-ovo colonization of the host and intestine, making this a hotly debated topic. Precisely when and what the host tissues are exposed to will likely have fundamental implications for host and immune system development, as well as potentially guiding the appropriate application of exogenous interventions seeking to influence early microbial colonization and developmental trajectory. Typically, and depending on the production system, these initial microbes will largely be of maternal or (immediate) environmental origin, acquired in a largely random process, thus seeding each individual with a unique microbiota composition, although functional profiles tend to be more similar. Together, the host, diet, and microbiome largely create biogeographical niches (e.g., substrates and O₂ availability, pH) within the gastrointestinal tract that support particular microbial communities, which challenges the collection of appropriate samples when seeking to explore these populations and their relationship with host health and growth performance. There remain many unknowns with regards to how the gut microbiome and host interact, and how these interactions manifest as relatively better or worse health or performance outcomes. We will explore important aspects of host-microbiome interactions to hopefully inspire insightful thoughts, discussion, and to encourage colleagues in their endeavors.

Key Words: Gut health, immune system, microbiota, microbiome, performance.

Presented at the 10th Symposium on Gut Health in Production of Food Animals 2022, St. Louis, USA.