Microbiota–host–immune interactions in nursery pigs: Dietary composition and its impact on intestinal microbiota and mucosal immunity for intestinal health

Abstract Global demand for pork, the most consumed meat worldwide, continues to rise, driving producers to adopt early weaning practices to increase pigs born each year. However, early weaning disrupts intestinal development and function, which can limit growth, therefore, understanding the mechanisms associated with maintenance of intestinal health are central to maximizing growth performance and productivity of pigs. The stressors of the post-weaning period induce changes to the complex microbiota–host–immune interactions that are further influenced by dietary nutrients. Central to these interactions is the recognition of changes in the intestinal microbiota by pattern recognition receptors of enterocytes and immune cells. Recognition of conserved microbial structures activates signaling cascades that regulate cytokine production, epithelial barrier function and redox balance. Bacterial influence on these pathways differs, with some bacteria promoting tolerance and anti-inflammatory signaling, whereas others induce pro-inflammatory responses. Dietary composition, including protein and non-starch polysaccharides content, and select feed additives, can influence the composition of the microbiota, thereby modulating microbiota–host–immune interactions. By utilizing nutriomics, an integrative framework that combines nutritional interventions with multi-omics technologies to connect dietary inputs to changes in the microbiota–host–immune interactions, this review highlights the complexity and context-dependent nature of these interactions and the role of nutrition to optimize intestinal health and enhance growth performance in nursery pigs.