This work sheds new light on the interplay between the gut, gut microbiota, and host physiological processes in production animals. The gut microbiome shapes health and susceptibility to disease and has become a leading area of research in the animal sciences. Gut health encompasses a number of physiological and functional features. Nutrient digestion and absorption, host metabolism and energy generation, a stable microbiome, mucus layer development, barrier function, and mucosal immune responses; all of which are required to interact to make an animal perform physiologically and according to its greatest genetic potential. This carefully presented book broadens our vision, approach and results on gut health and the ability to regulate animal production. Understanding the chemistry of microbiomes has broad implications, including providing functional annotations for the microbial genomes, insights into the chemical languages that link microbes to each other and to their host, and translational implications for precision veterinary medicine, environmental health, and sustainable animal agriculture and welfare. Experts working in microbiome research, host immunity, and animal production, veterinarians and researchers in livestock science will understand the great importance of this volume.