FILE - In this March 29, 2012, file photo. a worker sorts cuts of beef that are used in the manufacturing process of lean finely textured beef, also known as "pink slime," at Beef Products Inc.'s plant in South Sioux City, Neb. The announcement Tuesday, April 24, 2012 that mad cow disease was spotted in a California cow drew a rapid response this week from the beleaguered American beef industry which has been enduring one crisis after another, including the pink slime controversy. (AP Photo/Nati Harnik, File)
The department of agriculture has quarantined two farms in the wake of a "mad cow disease" investigation.
This is video of the California rendering plant where an infected cow was discovered last month.
The dairy farm where the cow came from has been under quarantine since the discovery.
U-s-d-a agents are working to see if any other at-risk cows are present at a second farm associated with the dairy.
This was the fourth case of mad cow discovered in the u-s since 2003.
Authorities say the infected cow was not intended for the food supply, and there's no reason to believe any beef is at risk.