Book excerpt: Antimicrobial resistance is a global and increasing threat. Stewardship campaigns have been established, and policies implemented, to safeguard the appropriate use of antimicrobials in humans, animals, and plants. Restrictions on their use in animal production are on the agenda worldwide. Producers are investing in measures, involving biosecurity, genetics, health care, farm management, animal welfare, and nutrition, to prevent diseases and minimize the use of antimicrobials. Functional animal nutrition to promote animal health is one of the tools available to decrease the need for antimicrobials in animal production. Nutrition affects the critical functions required for host defence and disease resistance. Animal nutrition strategies should therefore aim to support these host defence systems and reduce the risk of the presence in feed and water of potentially harmful substances, such as mycotoxins, anti-nutritional factors and pathogenic bacteria and other microbes. General dietary measures to promote gastrointestinal tract health include the selective use of a combination of feed additives and feed ingredients to stabilize the intestinal microbiota and support mucosal barrier function. This knowledge, used to establish best practices in animal nutrition, could allow the adoption of strategies to reduce the need for antimicrobials and contain antimicrobial resistance.