‘The old replacement index was too beef orientated’
The new ICBF replacement index will focus on the profit/lactation of the cow rather than the replacement value of the bull.
The revised index will place more emphasis on the milk and fertility production of females in the herd. This follows recent changes made by the ICBF to reduce the beef weighting for the replacement Euro-Star rating.
The revised index will now focus on improving the maternal characteristics of the national herd through the profit generated per lactation.
The ICBF and industry stake holders remodeled the existing index to increase the weighting placed on both milk and fertility by 6% each. Maternal traits now account for 41% of the replacement index.
The old index was too beef orientated according to the ICBF’s Chris Daly.
Under the old index farmers looked at bulls with high replacement values and thought they were assured of top notch replacement heifers, but this was not the case.
“The old replacement index placed too much emphasis on beef traits so these heifers may have had lower milk yields or fertility,” he said.
The old index took into account that half of the bull’s progeny were going to be male. The revised index focuses solely on the female progeny which reduces the focus on beef.
Daly also said that the index is now essentially more maternal and has more of a focus on the female’s milk and fertility.
The revised index will also look at the progeny. Under the new classification cows with higher potential milk and fertility traits will be rewarded.
But this is of no benefit unless the cow is capable of producing a calf with good genetics for growth and carcass characteristics.
“Farmers may get a shock when the replacement value of their best cow has fallen dramatically but over her lifetime the revised index is going to be much more reliable.”
Daly added that the figures may also benefit stock sourced from the dairy herd as a result of the associated changes to the milk and fertility sub-indexes.
This could potentially move the star ratings in line with Teagasc research which showed that beef heifers sourced from the dairy herd make better cows.
Breeds with higher maternal tendencies may also benefit from this readjustment, he said. But he added that there are elite replacement animals across all breeds.
“When you access the genetic trends there are higher numbers of elite replacements in some breeds rather than others. But all the breeds have elite replacement animals.
It just might be more difficult to find them in some of the breeds,” he said.
The figures for animals can always change, said Daly.
Dramatic changes to female indexes are rare and occur for the most part as a result of a change in the sire’s performance.
An unreliable sire has the potential to either increase or decrease and this will have consequences for the cow’s star rating.
He added that it is also very difficult to build the reliability for cows.
“Most cows have five to six progeny so it is impossible to achieve a reliability of 90% when compared to a bull with 20,000 progeny.”