The national and Chiba prefectural governments on Tuesday began probing the use of animal-based feed at a farm in Shiroi where the nation's first suspected case of mad cow disease has been found, government officials said.

Authorities will examine the types and amount of meat-and-bone meal used at the farm, as well as when it was used, to clarify how the cow was infected.

Meat-and-bone meal is a protein feed made from processed cow organs, skin and bone.