Strategies for the control of mastitis caused by environmental pathogens as a herd problem

Abstract

The group of environment-associated pathogens consists of bacteria which main reservoir is the environment. Coliform bacteria, Streptococcus uberis and enterococci belong to this group. Contamination takes place primarily between milking. However, infection occurs between milking as well as during milking. Due to a relatively short duration of infection, the herd prevalence is usually low. The bulk milk tank somatic cell count often is not increased because of frequent clinical mastitis. Strain differentiation typically reveals many different bacterial strains in a certain herd. However, there are also strains which have acquired the characteristics of cow-associated pathogens with a tendency to chronic infections. Because of their ubiquitous occurrence, cows constantly have to cope with environmental pathogens. Control measures include the prevention of new infection via reduction of contamination between and during milking. Important risk factors for contamination are the hygienic conditions in the barn and during milking. As to the latter, technical aspects such as vacuum stability and the risk of sudden air admission play a role. Furthermore, the local and systemic resistance are of importance, because they decide about the establishment and cause of infection. With regards to general resistance, stress-free housing conditions, adequate feeding (energy, fibre) and a good health management are necessary. With regards to the local resistance, acute and chronic teat changes which quite often can be linked to an inadequate milking procedure need to be considered. The dry period is a risk period for new infections, which can be prevented with long-term antibiotics or internal teat sealers. In summary, the control of mastitis caused by environmental pathogens requires a systematic approach.