Three new cases of mad cow disease have been discovered in three separate herds in France and a total of 432 animals were slaughtered.The disease was found in herds in the departments of Maine-et-Loire and Finistere in western France and in the Isere region in the Alps. These have brought the number of cases this year to 26.In 1999, French authorities discovered 31 cases of mad cow disease, or bovine spongiform encephalopathy. Mad cow disease is believed to cause a similarly brain-wasting ailment in humans known as Creutzfeld-Jacob disease.New cases of the disease are expected to break out in France until 2002, five years after authorities took rigorous measures to prevent more outbreaks. Mad cow disease has an average incubation period of five years.