While only two cases of mad cow disease (bovine spongiform encephalopathy, or BSE) have been confirmed in the United States since late 2003, they set off a national debate over how and to what degree American cattle should be tested for BSE. The current issue of the University of California's peer-reviewed California Agriculture journal focuses on the policy implications of the U.S. cases of the fatal bovine disease.

"Critical questions facing the U.S. policy establishment include which tests to use, how many cattle to test, which cows to test, whether to decentralize testing sites, and in particular, whether or not to allow testing on farms," writes Kate O'Neill, associate professor in the UC Berkeley Department of Environmental Science, Policy and Management, in the October-December 2005 issue.

In peer-reviewed studies, O'Neill analyzes U.S. regulatory policies regarding testing cattle for BSE, while UC Davis researchers describe a new DNA-based test to detect bovine contamination of cattle feed. In an editorial overview, leaders of the UC Davis School of Veterinary Medicine, Bennie Osburn (dean) and Donald Klingborg (associate dean), discuss how University of California scientists are contributing to efforts to better understand, monitor and control BSE. Related news coverage explores recent BSE-related policy and research. The entire journal, including PDF versions of all research articles in full, can be found online at http://CaliforniaAgriculture.ucop.edu.

BSE is spread among cattle via feed contaminated with rendered ruminant animals infected by similar diseases. This practice was widespread in the United Kingdom - where BSE devastated the cattle industry during the 1990s - but is less common in the United States. BSE has been identified in cattle from about two-dozen nations around the world, albeit at much lower levels than those found in the United Kingdom. Scientists linked consumption of BSE-infected beef to variant Creutzfeldt-Jakob disease, a new form of an extremely rare but fatal brain disease in humans.

In 2004, the USDA vastly expanded BSE testing rates, with the majority of the program voluntary. To date the USDA has tested nearly 500,000 cattle for BSE. Critics of the current testing policy note that about 36 million cattle are slaughtered in the United States each year, making current levels insufficient. They also have called for disclosure of geographic location, age and disease status of sampled cattle. But proponents argue that the low levels of BSE found in the United States do not warrant the huge expense of a significantly expanded testing program.


California Agriculture is the University of California's peer-reviewed journal of research in agricultural, human and natural resources. For a free subscription, call (510) 987-0044 or write to calag@ucop.edu. For a printed copy of California Agriculture, media should e-mail janet.byron@ucop.edu or call (510) 987-0668.

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