As the routine use of antibiotics is no longer accepted, the term ‘eubiosis’ has made its entry. It is a completely new way of approaching animal health: from fighting the microflora with antibiotics, towards supporting and cooperating with the favourable microflora. Eubiosis refers to an optimal balance of the microflora of the gastrointestinal tract. It is one of the key factors for optimal animal performance. Feed additives can be a very helpful tool to promote eubiosis and to overcome an imbalance in the microflora of the gastrointestinal tract, also known as ‘dysbiosis’.