Consider the fact that stomach acid is constantly being diluted by an influx of water and food. In humans, we subject our acid base to a variety of dilutants such as Pop, water, snacks thorughout the day and water by the gallon (for those of us who are healthier) and this dilutes the affect of the acid in our stomachs. That is why we see the corn passed along with the occasional peanut!!! It doesn't take a rocket scientist to figure out that maybe, just maybe, cows will pass undigested foods also due to their drinking water at various times of the day and that prions can indeed pass through the stomach without being degraded by stomach acids. My Father-in-law's herd would drink constantly and then their ability to pass waste product was astounding - it was more like a slurry mixed with chunks. Sorry, no other way to describe it. Those chunks were, in fact, undigested food matter or partially digested matter. Nontheless, prions coiuld easily hitch a ride through the sytem and into the intestinal tract where they could find a way into the rest of the animal.