Ruminants kept under natural conditions must be robust to be able to maintain optimal production, health and welfare. Robustness is the possibility to adapt to the circumstances. In dairy cows we search for animals that perform well on good quality roughage and a limited amount of concentrates. They maintain a good body condition, are in good health and cure easily when diseased. They can do without antibiotics or very limited medical treatment and are efficient in turning resources into production. Different breeds and crosses have different abilities: different farming and climatic conditions ask for different breeds