The United States dairy industry continues to experience significant monetary drain via losses associated with common diseases. Bovine mastitis is the costliest infectious disease currently affecting dairy cattle. While significant advances have been made in controlling some types of mastitis, the complex etiology of the disease and ongoing changes in dairy practices dictate that new and more effective methods for control and treatment be developed over time. Single site studies are often limited in terms of expertise and cattle numbers. A multi-state project provides advantages in terms of increased numbers of herds and cattle as well as multiple levels of expertise and contributions that are not present at single institutions.

Mastitis is defined as inflammation of the mammary gland and is almost always associated with bacterial infection within the cow’s mammary gland. Mastitis affects every dairy farm and approximately 38% of dairy cows in the United States experience clinical signs of disease. The National Mastitis Council estimates that this devastating disease costs the dairy industry more than 2 billion dollars per year or approximately $180.00 per cow. These losses are primarily due to subpar milk production and diminished milk quality, increased veterinary costs and antibiotic usage, increased cow mortality, and discarded of abnormal and antibiotic laden milk.

In the United States (US), cash receipts from marketing of milk during 2020 totaled $40.5 billion (NASS, 2021). In the US, the dairy industry contributes >$140 billion per year to the national economy and provides > 900,000 jobs making it a vital part of our nation’s economy and food system (Adcock et al., 2015; ERS, 2015).  

Currently, intramammary antimicrobial therapy is the most widely used and most effective management strategy to eliminate intramammary infections and alleviate pain and suffering. Bovine mastitis is a unique disease wherein multiple infectious agents can trigger an inflammatory response. When considering treatment of an individual cow for mastitis, the causative infectious agent is usually unknown. Therefore, producers commonly treat with different combinations of antimicrobials and routes of treatments. This common management strategy can lead to overuse of antimicrobials, thus increasing the risk of residues in milk and the selection for antimicrobial resistant pathogens. Growing consumer concerns regarding antimicrobial use, the risk of antimicrobial residues in milk and meat and the potential for antimicrobial resistance have led to the examination of alternative strategies for controlling mastitis while reducing the use of antimicrobials on-farm, which is one of the primary goals of this multi-state group.

The primary goal of NE-1748 has been to coordinate and enhance multidisciplinary research efforts on mastitis that are being conducted at various laboratories throughout the United States and internationally, e.g., Canada, Australia, and Europe. The magnitude and scope of attempting to solve the problems arising from mastitis extend far beyond the ability of any one institution. The ability to cooperate on a regional, national, and international basis allows the integration of resources and knowledge to address these problems. Recognition of the need for a coordinated effort to study resistance of the pathogen and the need for non-antibiotic alternative therapeutics for the dairy cow for the control of mastitis resulted in the design and initiation of multi-State Project NE-1748. The NE-1748 project has provided a forum for new and established researchers to develop collaborative relationships, and to share resources and expertise. NE-1748 meetings are well attended, and 20-40 presentations are typically made by participants each year. International visitors and collaborators are often included in these presentations. We are proposing to continue these efforts with NE-2248 in a multistate and international setting to better control mastitis, reduce antimicrobial usage for the treatment of mastitis, and reduce the negative economic consequences of this prevalent and burdensome disease.

The mastitis research workers group has met in conjunction with the NE-1748 annual meeting for many years. International visitors and collaborators are often included in these presentations. In addition to the mastitis research workers conference, the NE-1748 members provide new management strategies to reduce antibiotic usage and technology transfer to the scientific community and industry stakeholders. In the last 4 years, members of the project have collectively published multiple book chapters, peer-reviewed journal articles, abstracts and proceedings, and presented numerous oral and poster presentations related to mastitis, milk quality, and food safety. Venues for oral and poster presentations have included the National Mastitis Council regional and annual meetings (attendees include researchers, veterinarians, dairy producers, and representatives from industry), Conference for Research Workers in Animal Diseases, American Association of Bovine Practitioners annual meetings, International Dairy Federation meetings, American Dairy Science Association meetings, World Buiatrics Congress meetings, American Society of Microbiology meetings, Conference on Production Diseases in Farm Animals, Plant and Animal Genome Conference, Agriculture and Agri-Food Canada - Food Safety meetings, American College of Veterinary Internal Medicine annual forum meetings, and several regional extension and veterinary continuing education meetings.

The continuation of the NE-1748 multistate project by means of the proposed NE-2248 multistate project is of utmost importance to foster impactful mastitis research leading to the provision of science-based information to dairy producers and the dairy industry. The impact of the European Union’s strict enforcement of import regulations on milk quality highlights the need to continue efforts to reduce the incidence of mastitis and antibiotic use. These regulations require milk export companies to certify that any farm contributing milk must show a bulk milk cell count below 400,000 cells/mL. This regulation has been supported by the National Mastitis Council as a goal for all US dairies. Mechanisms leading to improvement in milk quality, dairy animal welfare, and appropriate use of antimicrobial therapeutics form the basis of research conducted in the NE-1748 multistate project. It is clear that continued mastitis research and education are required to maintain the global competitiveness of the US dairy industry. Furthermore, the animal agriculture industry in general is under closer scrutiny than ever before by various interest groups. The work of NE-1748 is clearly focused on reducing mastitis, reducing antibiotic use and improving economic outcome and animal welfare. Mastitis is the most significant animal health issue in the dairy industry. In summary, continuation of the NE-1748 project is a productive group of collaborators that has provided new and meaningful information to all levels of the dairy industry from the bench scientist to the dairy producer with regard to bovine mastitis control, treatment and prevention. In the next 5 years we will continue to pursue collaborative projects under our 3 stated objectives which will lead to new information of value to the management of dairy cattle mastitis. Mastitis is an evolving disease syndrome, as is the science that studies mastitis; therefore, continued research efforts are needed.