LIC: Faster Bull Team Change Reflects Genetic Progress
In the past, a bull could sit comfortably in a breeding team for several years with little change, but today, that’s no longer the case.
Changes to these breeding values and the flow-on effects for the overall measure of cow and sire genetic merit Breeding Worth (BW) were implemented February 16, focused on the conversion of liveweight information into a mature weight equivalent.
“Historically this conversion has been done within the liveweight animal evaluation model, but over time the information has become heavily weighted towards data for two-year-olds which skews the calculation,” says NZAEL manager Jeremy Bryant.
The new method converts all weights to a mature equivalent before the data enters the liveweight animal evaluation model.
“The aim of the NZAEL research was to improve the accuracy of genetic prediction for liveweight, which then leads to a more accurate BW for dairy farmers,” says Bryant.
The year-long research has been reviewed by the standing advisory committee of NZAEL which includes leading geneticists from New Zealand, and approved by the NZAEL Board.
The effect will be seen in all animals, the firm says, especially when comparing breeds. The liveweight breeding values for Jersey and crossbred animals generally decrease, and those for Holstein Friesians increase.
The routine updates of economic values in BW also came into effect on February 16.
“NZAEL updates economic values every year, in order to keep aligned with market signals,” says Bryant.
This year, moderate changes are seen in the value assigned to fat and protein yield. These come from a combination of a falling milk price, as well as slight changes to the calculation of milk volume penalties and flow-on effects for fat and protein yield.
The combined effect of the liveweight changes and economic value update mean that, on average, the BW of herds will reduce.
“Farmers with predominantly Jersey dairy cattle will see a slight increase in herd BW and farmers with predominantly Holstein Friesian dairy cattle should notice a decrease in herd BW. Crossbred herds will be intermediate between the two breeds,” says Bryant.
