The first two cases of Bovine Spongiform Encephalopathy found this year were both detected in herds in Co Cavan, the Department of Agriculture and Food said last night.
The animals, according to the Department, had been born in 1995. It was not until 1997 that animal feed controls became fully effective.
Public confidence in these controls was badly hit late last year when the Department disclosed that three animals born since 1997 had contracted the disease.
Investigations into where these beasts had contact with contaminated meat and bonemeal are continuing.
A statement from the Department said the underlying trend remained positive, and the increasing age profiles of animals confirmed with the disease indicated that the enhanced controls introduced in 1996 and 1997 were proving effective.
There were 333 cases of the disease in the national herd last year, the highest figure on record. However, a high proportion of these were uncovered in animals at knackeries or in casualty animals.