Many articles published in the M2-magazine have outlined the benefits of various management strategies aimed at reducing mastitis. Examples of such strategies include, optimal nutrition and housing, a proper milking routine with post-milking disinfection, vaccines and dry-cow therapy. The benefits of these strategies include increases in animal welfare, improved milk quality and a better return on investment to the producer. There is also an increasing interest in breeding dairy cows that have enhanced resistance to mastitis. In classical breeding terms, the potential for genetic progress is directly dependent on both the accuracy of selection for the phenotype, and the amount of variation existing in the current population from which future sires and dams can be selected.