Epigenome editing is a set of molecular approaches that aims at modifying one or several epigenetics marks in one or a few target genomic regions. It can be used to decipher the causal regulatory mechanisms governing gene expression, to validate putative distal regulatory elements, and to modify gene expression levels. The long term repression or activation of a target gene of interest without altering the DNA sequence of a cell constitutes one of the most promising applications of epigenome editing, including in farm animals. Here we present the main molecular tools currently used to perform epigenome editing in vitro or in vivo: the guidance systems (including CRISPR based), the epigenetic effector domains in use, and the delivery method available in vitro or in vivo. A list of studies reporting in vivo epigenome editing in animals (mostly in mice) is proposed, highlighting methodological choices that have been made by their authors. For example, some approaches require an alteration of the host DNA sequence (i.e. using lentiviral infection), while others let the host genome intact. Some approaches have effects across the whole organism, and even putative inter-generational effects, while other approaches target a single somatic organ. Finally, we list potential applications in farm animal species, ranging from research to commercial solutions. We discuss the implications of the different methodological options, including in terms of economic feasibility and public acceptability.