<p>Antimicrobials are currently an indispensable pillar of the animal production industry, relied upon to treat diseases that could otherwise severely impact animal welfare and productivity. However, overuse of antimicrobials is driving the selection of drug-resistant microbes. Coupled with the rising demands placed on animal production systems by the growing human population, we now face an increasingly urgent need for new strategies to address animal diseases and their impacts on productivity, efficiency, and welfare. The identification and development of alternatives to antimicrobials is therefore a critical and fast-growing field of research. The STAR IDAZ International Research Consortium recently conducted workshops that recruited international experts to develop research roadmaps aiming to stratify, organise, and clarify the ongoing research and outstanding questions that currently define the field of alternatives to antimicrobials. This review will explore the roadmap that deals with immunomodulators, a broad class of technologies that aim to beneficially alter host immunity in ways that promote animal health and growth, mitigate disease, and improve welfare at the human-animal interface. We will discuss the STAR IDAZ immunomodulators roadmap in detail, addressing the foundational biology underlying immunomodulation; the fields of research that link livestock immunity and metabolism with response to infections; and the immunomodulator technologies that are currently under development.</p>