How the Pasture Profit Index works works
Selecting grass varieties is a process that's undergone somewhat of a revolution over the last year, with the unveiling of Teagasc's long awaited Pasture Profit Index (PPI) ranking system for all grass varieties.
The index works on the same principle that is used in the EBI and €uroStar beef indexes.
Following extensive research over the last decade by a team led by Moorepark's Michael O'Donovan, a formula has evolved that places different values on the key characteristics of each grass variety.
"This formula will allow us to have the best recommended list in Europe," said Dr O'Donovan.
The first element in the formula is the amount of grass that any particular variety can grow. But Dr O'Donovan was not content to just take an overall yield for each grass.
Extra weightings are given to varieties that are able to produce more grass on the shoulders of the grazing season, because these are the periods where there is greatest scope to replace expensive concentrate feeding.
Therefore, kilograms of grass drymatter produced in the spring are valued at 16c, compared to 11c in the autumn and just 4c during the summer. These values account for 31pc of the weightings in the overall index.
Silage yield is also calculated separately, again with different values attributed to first and second cuts.