Disturbances of the intestinal environment and changes in the proportion of microorganisms in the gastrointestinal tract are the main causes of agastrointestinal diseases in horses. New feed additives such as Biochar are a promising solution to such problems. Biochar is a plant-derived carbon rich, charcoal-like substance produced by pyrolysis during bioenergy production. Due to its large and highly porous surface area, biochar provides a favourable habitat for microorganisms and is also a good electrical conductor, facilitating electron transfer between syntrophic organisms. Additionally, data from previous studies suggest a possitive effect of biochar on reducing pathogenic bacteria in faeces in favour of host-beneficial species.