A guide to network analysis, multi-omics integration, and applications in livestock microbiome research.

The function of the livestock gut microbiome in driving animal growth, health, and methane emissions is controlled by networks of interactions among microbes. A major challenge is to move beyond simply listing microbial members to understanding these interaction networks, which determine how the community functions as a whole. This review synthesizes how network analysis, combined with multi-omics data, can meet this challenge. We focus on the critical task of identifying keystone species, the disproportionately influential microbes that direct processes like fiber digestion and immune function, yet are often missed by standard surveys. We evaluate a progression of methods, from identifying correlated species to building models that integrate genomic, metabolic, and host data. This integration is key to separating true ecological relationships from statistical noise and to linking microbial presence to function. We highlight how computational techniques like metabolic modeling and machine learning are turning networks into predictive tools. Finally, we outline the path forward: field-ready studies that track microbiomes over time, the development of livestock-specific metabolic models, and analytical standards that will allow research to translate into practical strategies. The goal is to provide a framework for using network science to actively manage the microbiome, enhancing sustainable livestock production.