Another 20 cases of BSE have been identified in the past three weeks, according to the Department of Agriculture, Food and Rural Development.
The latest figure - four more than last December's tally - brings the total number of cases identified in the Republic this year to 149, the highest since the disease was identified here in 1989.
There now have been 596 cases of BSE, 580 of them single cases.
There is, however, a positive element in the December figures because the majority of the infected were older cows, with none under four years old.
There was one 4-year-old cow; five were aged five years; six were aged six years; two were aged seven years; two were eight years old; and there were two 12-year-olds, according to a Department spokesman.
He said investigations were continuing into the exact ages of the other two December cases which were found, under the increased surveillance system, at a knackery.
"There are some difficulties in identifying the exact ages of these two cases but our inspectors are satisfied that they were older animals, at least six years of age," said the spokesman. "We are pleased that the age profile of the victims continues to rise and that two-thirds of the cows which were found with the disease this year were aged six years or older." The cases, which included one so-called cohort animal identified in a herd which was slaughtered last month, were on farms all over the State. Co Cavan had three cases; there were two cases in herds in Meath, Westmeath and Wicklow, and single cases in herds in Sligo, Leitrim, Clare, Tipperary, Dublin, Laois, Longford, Galway, Limerick and Wexford.
Dr Patrick Wall, head of the Food Safety Authority of Ireland, said the rise in the figures had been expected, given the increased surveillance in recent months.
It was interesting, he said, that none of the animals was below four years, indicating that the disease was now being confined to the older cows which had been exposed to contaminated meat-and-bone meal before 1996/1997.