Scientifically-sound and statistically-valid information is critical for sound decision-making. Within the areas of interactions among animal health, production, welfare, product wholesomeness, and the environment, the purpose of the monitoring and surveillance efforts of the USDA,APHIS,Veterinary Services is to help address these information needs.

The structure of the dairy industry is currently transforming as dairy operations become fewer in number, larger in size, geographically more western, and higher in production level. Amidst these changes, critical animal health issues have arisen. Each of these issues involve areas with information gaps. It is well understood that bovine viral diarrhea virus, for example, can cause severe acute disease in cattle that appears to be prevented by vaccination and avoidance of viral exposure through the employment of biosecurity measures. What is not known is the percent of dairy cattle at risk of disease (percent unvaccinated, extent of cattle movement in and out of herds). Biosecurity and management information is also needed to assess risks of disease due to other pathogens. Anther pathogen of concern is Mycobacterium bovis. There are currently only a handful of M. bovis quarantined herds in the U.S. However, the reasons for endemnicity of M. bovis in the El Paso milkshed and the potential risk from cervidae is unclear at this time. Related to Johnes disease, it is known that there are many Mycobacterium paratuberculosis infected herds in certain parts of the U.S. and that this agent has negative effects on milk production and cow longevity. What is not understood is the herd or animal prevalence in the U.S. and its potential association with Crohn’s disease in humans.

In this age of NAFTA and GATT, additional informational needs have arisen, related to the need to accurately detect regional differences in disease and agent occurrence, as well as to document the absence of certain disease agents. Bovine spongiform encephalopathy is a key example. There have been no known positive cattle in the U.S., despite prospective monitoring of cattle brains for lesions. However, continued efforts are needed to satisfy international concerns.

Outside of the dairy farm environment, dairy pathogens can affect humans also. The Centers for Disease Control and Prevention has outlined, as part of the Healthy People 2000 Report, the goals of reducing the incidence of human foodborne disease caused by Salmonella, E. coli O157:H7, Campylobacter jejuni, and Listeria monocytogenes. As part of this effort, a great deal of information is needed to better understand relationships between these pathogens and on-farm management practices that might potentially reduce the number of pathogens entering the food chain.

Beyond microbiological concerns, other quality measures of dairy products are needed. USDA,APHIS,VS has initiated national milk quality monitoring, using Dairy Herd Improvement Association individual cow somatic cell count data, and is expanding this monitoring to include monthly bulk tank somatic cell count data. This information is needed to document the high quality of our milk supply both domestically and internationally.

A final area of concern is the impact of cattle management practices on the environment, specifically when this affects human health. One of the agents of concern is Cryptosporidium parvum. What is known is that this intestinal agent is commonly found in a wide variety of animal species (including almost all dairy operations). In dairy cattle, C. parvum is most commonly detected in calves less than four weeks of age. What is not completely understood is whether management strategies could be employed to prevent contamination of surface water sources from cattle shedding cryptosporidia, and whether this could play an important role in prevention of human disease.

To answer these questions will require a great deal of effort and resources from many groups and individuals across the dairy industry. One of the ways that USDA,APHIS,VS can help with this process is through conducting periodic national studies. The first NAHMS national dairy study, the National Dairy Heifer Evaluation Project, was conducted in 1991-92. The second NAHMS dairy study will start in early 1996. We are currently working with focus groups representing dairy producers, veterinarians, animal health officials, and others to assess the key informational needs to be addressed in this study. This study will be national in focus, statistically-based to allow national estimates, and involve voluntary on-farm data collection and biologic sampling. Individual producer information from participant herds in the study will remain confidential. With broad cooperation across the dairy industry, this NAHMS dairy study will be successful in providing information for better decision-making that will benefit the entire industry.