Growth and Development Symposium: intestinal development and growth.

The gastrointestinal (GI) tract is a critical organ system mediating nutrient uptake and use by the animal. Understanding factors that influence GI development, growth, and function is critical to improving management and therapeutic approaches to maximize health and production efficiency of livestock. These factors are diverse and include animal nutrition and nutrient interactions with the GI tract, animal genetics, and the physical and biological environments of the animal, such as the interactions between the host and its diverse GI microbiome. Recent advances in scientific technology and computing capacity now permit the systematic study of genes and their products, including those derived from the animal GI tract, as well as the complex microbial communities within the GI tract. Thus, the interactions of microbial communities with their host animals and their impacts on animal production and health are increasingly being studied and are becoming better understood. A special case to consider is the development of the GI tract of neonatal livestock and newly hatched poultry. The fetal GI tract is not exposed to microbes prepartum or prehatching, but the microbial population becomes established during parturition or upon first feeding. The colonization of the GI tract is rapid and complex with numerous types of microbes. Increasing evidence suggests that manipulating the diversity of the gut microflora can affect animal health and can be accomplished through changes in production practices. For example, results derived from studies of humans and rodents indicate that the composition of the gut microbiota can influence the efficiency of energy extraction from the diet, as well as the production of inflammatory cytokines in the gut that contribute to obesity and metabolic syndrome (Frank, 2011). Furthermore, the gut microbial population influences nutrient homeostasis including that of AA, vitamins, electrolytes, and short-chain fatty acids (Frank, 2011). Thus, in theory, the diversity of the GI microbiota could be manipulated or optimized to promote animal production and well-being (Cook, 2011). The combination of advances in new technologies and the potential impacts of the interactions that affect GI tract development and, ultimately, animal development, health, production efficiency, and product quality, stimulated the initiation of a symposium to highlight current knowledge of these complex interplays. This symposium was presented at the Joint Annual Meeting of the American Society of Animal Science, the American Dairy Science Association, the Poultry Science Association, the Asociación Mexicana de Producción Animal, and the Canadian Society of Animal Science on July 12, 2010, in Denver, Colorado. Animal scientists are keenly aware that the goal of animal agriculture is to provide safe, nutritious, and affordable food that can be produced efficiently and with minimal adverse environmental impacts. The advent of advanced molecular technologies provides new opportunities to gain insights into intestinal development and function, and to develop novel livestock production practices to enhance our ability to achieve the goals of animal agriculture, while also benefiting human health. This theme was recapitulated by Frank (2011), who proposed that it is possible to promote greater health in humans through healthier livestock, specifically by applying metagenomics approaches to the understanding of interactions between the GI microbiota and the host. The thesis of his presentation was that study of the human microbiome can foster more healthful animal agriculture. The notion that dysbiogenesis, imbalances in the make-up of the complex, commensal microbial GROWTH AND DEVELOPMENT SYMPOSIUM: Intestinal development and growth