The base cow for the Economic Breeding Index (EBI) is to be updated by 10 years. There is currently a separate base for production and fertility traits. The current EBI figures for the production base is 1995 born cows who were milk recorded in 2000. The current EBI figures for the fertility base is sires born between 1988 and 1992 with over 90% reliability. This means that the current EBI system is comparing today’s cows with the average of the cows born in 1995 for production and the average of the 1988 and 1992 cows for fertility.
The new base will be the same for both milk and fertility. The new base for production & fertility will be 2005 born cows, calved and milk recorded in 2007, with at least 2 years out of 5 milk recorded. What will all this mean? The impact of the base change can be seen in the below example
Every dairy animal will be scaled back by €71 EBI as a result of this base change, however the base will be changed in September during a genetic evaluation so as always there will be more data on animals added to their index so the exact change in EBI will also depend on what data has come in on a particular animal (change in EBI seen in September may not be exactly €71). This will be the same for every animal in the country so there will not be a re-ranking of bulls as a result of the base change alone (any change in ranking will be due to the genetic evaluation process, the same as always).
This base change alone will not cause a re-ranking of any bulls.
Herd-owners need to focus on PTA (or sub-indexes) when selecting bulls that are suitable for their requirements. The HerdPlus EBI report should be used to achieve this. You need to know where your herd stands currently in order to make genetic gain, for example if your herd average is €50 using bulls with an average EBI of €100 will mean that your calves born as a result will have an average of €75. This represents genetic gain as the calves are €25 greater than their dams. To view the full slideshow presented by Francis Kearney at a recent Dairy Industry meeting please click on the pdf icon below