Biosecurity on dairy operations: hazards and risks.

The objective here was to present a model for considering biosecurity related to infectious diseases on US dairy operations using a risk assessment framework. With the example of an important dairy cattle pathogen (Mycobacterium paratuberculosis), I followed risk assessment steps to characterize risks related to the use of certain management practices and possible risk reduction within an infectious disease biosecurity program. Biosecurity practices focus on the prevention of introduction of these pathogens to the dairy, and estimates of the risks associated with introduction of different sources of cattle are presented. In addition, biosecurity practices also limit the transmission of these pathogens within an infected dairy operation, especially those focused on sick cow management, calving area management, and manure management. Recent information from the National Animal Health Monitoring System (NAHMS) Dairy 96 Study indicates that many of these practices have not been adopted on US dairy operations, indicating both risk of disease and opportunity for animal health improvement.