1a. Objectives (from AD-416)
The objective of this agreement is to build upon a long-term project designed to evaluate the impact of intervention strategies on Johne’s disease dynamics, milk and beef quality (particularly with respect to zoonotic bacterial pathogens), economics and sustainability through intensive longitudinal follow up of well-characterized research/demonstration dairy farms. Long-term goals are to validate intervention strategies to support best management practices (BMPs) and to optimize intervention and monitoring strategies given the constraints on time, labor and financial resources in modern dairy herds. In addition, a national resource bank (data and biological specimens on well-characterized animals) will be maintained for current and future monitoring and research on dairy cattle diseases. Emphasis will be on longitudinal data collection on endemic infectious diseases of public and animal health concern.
1b. Approach (from AD-416)
Pathogens are of increasing concern on dairy farms and in dairy products. The production of safe and wholesome food from U.S. farms requires control of the production process on the farm. Specific focus areas in this process are biosecurity, food safety and animal health. To be able to scientifically support regional process control programs there is a need for longitudinal research on commercial dairy farms throughout the United States. For several years, Cornell University, The Pennsylvania State University, The University of Vermont, and the University of Pennsylvania, which are all participants in the Regional Dairy Quality Management Alliance (RDQMA), have collaborated with the USDA’s Environmental Microbial Safety Laboratory to study the disease dynamics of endemic infectious diseases on three operating dairy farms. The goal is to identify sites that act as reservoirs for pathogenic microorganisms that affect animal health and/or decrease product quality because of their zoonotic nature. Serum, feces, bulk tank milk, and environmental samples (water, bird and rodent feces, feed, etc.) will be taken on the farm. In addition, tissue samples will be obtained from carcasses of culled animals. Samples will be distributed among the university and ARS researchers for analysis to determine the presence of Mycobacterium avium paratuberculosis (the causative agent of Johne’s disease in cattle) and for Salmonella enterica, Escherichia coli O157:H7 and other enteropathogenic forms of E. coli, and Listeria monocytogenes (human food-borne pathogens of concern in dairy products). This research is the first to attempt a comprehensive analysis of both Johne’s disease and food-borne pathogens on working dairy farms. We have gathered extensive baseline data for these organisms on three farms and have set the stage for investigation of the effect of interventions, in the form of BMPs, on animal health and product quality.
3. Progress Report
Through this agreement the cooperator provided access to samples from a dairy farm in New York and provided expertise in epidemiology for the entire project. Since the samples required for the study of the occurrence, maintenance, and persistence of Salmonella, Listeria monocytogenes, and pathogenic E. coli were identical to those required for the study of Mycobacterium avium Paratuberculosis (MAP), which was of interest to the cooperator, joint sampling was conducted. Milk, milk filters, and environmental samples from a dairy farm in New York were taken on schedule and distributed to laboratories for analysis. A database of all the data generated in several labs during the course of the project was maintained as agreed. Molecular analysis of Listeria monocytogenes isolated from milk, milk filters, bovine feces, and environmental samples was conducted and the results published in peer reviewed journals. Data documenting Salmonella outbreaks on another project farm were used to construct models to describe the dynamics of commensal Salmonella infections in dairy herds. A report describing the molecular ecology of MAP on study farms was published in a peer reviewed journal. The modeling of MAP infections on dairy farms, in light of the discovery of the role of MAP supershedders, and the likely results of various intervention strategies was described in papers published in peer reviewed journals. MAP work, as a part of this project, was terminated. The ADODR has monitored activities associated with this project through frequent phone calls, conference calls, and emails. A meeting of all major participants was held.