Mastitis is the most expensive, often recurrent, disease in dairy farming. The inconvenience and costs associated with clinical mastitis are most visible. However, subclinical mastitis (cows with elevated somatic cell count) is responsible for the greatest losses (reduced milk production, fines, etc.). This has already been the subject of long-standing attention through the 10-point programme. This comprises measures for the prevention and control of mastitis, supplemented by guidelines for comfort, hygiene and housing. Still, a very big amount of preventive and curative antibiotics are used in the battle against mastitis worldwide.  In order to reduce this antibiotic use, and thus antibiotic resistance, it is crucial to support the cow's own immune system.