State agriculture officials are attempting to calm fears about the beef supply in the wake of the discovery of a single case of suspected mad cow disease in Washington State. State Agriculture Director Peter Hofherr says Missouri has been part of the USDA Mad Cow Disease surveillance since concerns about the disease arose. State agriculture officials do worry about the psychological impact on the cattle markets. A market expert for the Department says markets will be down with word of the discovery. And, at present, no one knows how far down they will go and how long they will stay there.