AABP Executive Director Dr. Fred Gingrich is joined by Dr. Drew Magstadt from Iowa State University to discuss Johne's disease in beef cattle. Johne's disease is caused by Mycobacterium avium paratuberculosis that studies have shown affects up to 50% of cow-calf herds, however a small percent of animals are infected (3% to 8%).  Magstadt discusses some of the unique challenges of combating this disease in cow-calf herds where calves are raised with the adult cows, contrasted with calf separation from the adult herd on dairy operations. Some of the frustrating problems when implementing a Johne's control program in beef herds include the chronicity of the disease and the limitations of the various tests that are available. We talk through the tests that are available for beef herds and the advantages and disadvantages of each. Testing options include fecal culture, fecal PCR, complement fixation and serum ELISA antibody testing. Magstadt discusses a retrospective study he performed from submissions at the Iowa State University Diagnostic Laboratory looking at serum ELISA and fecal PCR submissions from the same animal and then evaluating if the submissions were from herd surveillance or non-surveillance sampling. They compared serum ELISA S:P ratios with fecal PCR results and found that high positive S:P ratios were highly correlated with a positive fecal PCR, a medium positive S:P ratio showed about 50% of cattle shedding MAP in the feces, and a low positive S:P ratio typically had a negative fecal PCR result. This information can help producers making culling decisions. Submitting both serum and feces to the lab is a good idea so that additional tests can be completed without the need to collect additional samples from the herd. He suggests that veterinarians should work with producers to develop a control program and to talk to your diagnostic lab about testing options, sample processing and pooling samples. Veterinarians can also decrease the cost associated with testing in pooled samples by looking at body condition and fecal scores on cows as they are processed for sample collection and separate those samples from non-clinical cows. Magstadt also reminds our listeners that contamination can be a significant issue when collecting samples and veterinarians and processing crews should be aware of the possibility of contaminating multiple samples if care is not taken to ensure clean samples. Eliminating Johne's disease from a beef herd is a multi-year endeavor that requires a team effort from the diagnostic lab, veterinarian and producer that also requires instituting management practices to decrease the introduction and spread of the disease within a herd.