UPDATE: Farms quarantined after BSE discovery

The farm where the cow was initially discovered was quarantined since the discovery, the second quarantined farm has close associations with that farm. The USDA is still trying to determine if any at-risk cattle are present at either of the two farms.

According to a USDA statement an investigation has been launced at a calf ranch where the initial infected cow was raised 10 years ago.

The USDA says that since the discovery of the infected cow, they have identified 10 different feed suppliers that delivered animal feed to the farm. Determining if the cow became sick from feed is an area where investigators are focusing close attention.

Authorities have determined the infected cow gave birth twice. One calf was stillborn and the other was located on a farm outside of California. That cow was subsequently euthanized and tested negative for mad cow disease.

BSE is usually transmitted between cows through the practice of recycling bovine carcasses for meat and bone meal protein, which is fed to other cattle. In this case, the Agricultural Department reported that the cow had a rare form of BSE not likely carried by contaminated feed.

Since 2004, the USDA has removed the brain and the spinal column, the parts suspected of causing mad cow disease in humans, from the food system.