The number of BSE cases has risen to 185, the highest figure on record for any six-month period since the disease was first identified here in 1989.
Five new cases were identified in the last week of June in herds in Kerry, Cavan, Limerick and Cork. All the animals were born before the controls on feeding meat and bonemeal became fully operative.
The two animals in Kerry were aged six and seven years, and the Cork and Limerick cows were both six. The Cavan cow was seven. Two of the most recent cases were found on farms and the other three at knackeries, where all injured or sick animals are now being tested for the disease.
This active surveillance testing has brought forward the surge in cases in the last two years. So far this year, 286,000 tests have been carried out, compared to 126,000 last year.
All animals over 30 months are tested for the disease in meat-processing plants.
The Department of Agriculture said the underlying trend remained positive because of the increasing age profile of the animals, indicating the controls put in place in 1996-1997 were proving effective.