Further improvements to the EBI in development for deployment

The EBI has evolved since its introduction in 2001 by including traits as they become available, more economically important, and more recently, more socially and environmentally significant. Now, over 20 years on from the EBI introduction, further improvements to the EBI are in development for deployment.

Improvements to the EBI in the future include the introduction of;
1. A new sub-index; Carbon Sub-Index
2. A new trait; Age at Slaughter
3. An updated trait; Somatic Cell Count
4. An updated sub-index; Female fertility sub-index
5. Inclusion of Minor Breeds

Carbon Sub-Index
Reducing the industries carbon footprint through breeding has been identified as one of the key areas to assist in achieving our GHG emission targets. Breeding has the advantage that the benefit of improvement is cumulative over time. To this end, the dairy industry has been selecting on EBI based on traits but at the same time have indirectly been selecting for a reduced carbon footprint. This is because there is a negative correlation between EBI and carbon output; the higher your EBI, the lower the carbon footprint. This indirect selection for lower emissions equates to reducing the carbon footprint by 14% kilogram of milk solids produced which is a good new story for the industry.

However, can we reduce our carbon footprint even faster through breeding? Simple answer is yes. Selecting directly for lower carbon emissions would drive down our carbon output. For this reason, a new carbon sub-index is set to be introduced to the EBI at the end of the year. With the introduction of this new sub-index in the overall EBI, the industry will be able to directly (rather than indirectly) select for reduced carbon output. The new sub-index uses exactly the same principles as to how the EBI is calculated but instead of the output being profit, in this new sub-index the output would equate to carbon.

Farmers will see a new sub-index category on their reports and profiles and should take note of the change of relative emphasis across all sub-indices to allow for the new sub-index introduction. Research and validation is at an advanced stage with implementation of the new sub-index estimated to occur in late 2022.

Age at Slaughter
The principle of “more from less” is the key foundation upon which ICBF’s genetic evaluation programs for beef traits are based. With the clear objective of increasing the sustainability of our national herd, a new trait of interest has come to fore in the form of age at slaughter. Having a younger age at slaughter is both economically and environmentally beneficial where the trade-off on the kilograms of beef output is minimised. One of the most significant potential outcomes from selecting on EBI as well as focusing on breeding a younger age at slaughter, while maintaining all the economic benefits of beef output, is that there is clear evidence that higher genetic merit animals have significantly lower methane output/day than lower genetic merit animals. Selecting directly for a younger age at slaughter has the potential to further drive down our carbon footprint from the national herd if introduced into our breeding indices. It is expected that age at slaughter will be introduced to the suite of traits under the Beef sub-index in the EBI.

Somatic Cell Count
In line with international best practice, Ireland will move to apply the Test Day Model (TDM) approach for genetic evaluation of somatic cell count (SCC), as opposed to the previous approach of a predicted 305-day SCC. The TDM approach was introduced for the production trait genetic evaluations back in 2018 and it is planned to introduce the new TDM SCC evaluation to replace the 305-day SCC later this year. The TDM is named as such because every test day record on each cow is used rather than the previous 305-day model, which used a standard lactation curve for each cow regardless of the number of milk recordings throughout the year. The TDM is better able to account for environmental factors on the day of the milk recording, such as weather, feed levels and grass quality. The new TDM SCC will replace the current 305-day SCC which is included in the Health sub-index in the EBI. The impact on the overall EBI on average will be +€3 for AI sires and +€2 for cows.

Female Fertility Sub-Index
Female fertility has been identified by Irish farmers as one of the main areas of focus in their breeding programmes which is unsurprising given both its economic and environmental impact on the industry. The current fertility sub-index includes calving interval and survival which have contributed to rapid improvements in the mean reproductive performance of the Irish dairy herd over the last two decades since its introduction in 2001. The last update to the female fertility evaluation was in 2010 and research work is underway to investigate new methods to evaluate female fertility and to provide more precision during selection on these traits to improve the accuracy of the genetic evaluations and accelerate genetic gain. New traits of interest are being investigated with a specific focus on the seasonality of the national herd. Research into this area is expected to continue into next year.

Inclusion of Minor Dairy Breeds
The update planned for the dairy genomic evaluation will expand the list of breeds eligible for a genomic evaluation. When across breed genomic evaluations were introduced in January 2020, it initially included only 7 breeds (HO, FR, RW, JE, MO, NR, AY). In the next update of the evaluation, another 10 breeds will be added to the evaluation (BS, SI, MY, SH, SR, KE, NO, RB, RD, MS). This means that an extra 5,000 animals will receive a genomic evaluation, and an additional 1,500 animals will be added to the training population. The impact on the EBI for currently genotyped animals will be minimal. The animals that will receive a genomic evaluation for the first time will have an average EBI change of -€2 and an average increase in reliability of 14%.