The Economic Breeding Index (EBI) was introduced in 2002 as an overall profit index for ranking animals based on future dairy performance. The index aims to provide farmers with a tool to help maximise farm profit by identifying animals whose progeny will be most profitable under future Irish production systems. Analysis of commercial farm data (using the e-profit monitor) has indicated that each €1 increase in herd EBI results in a €2 increase in profit per cow per lactation. The latest EBI trends are illustrated below in Graph 1. This is based on 1ST calving females entering the dairy herd from the July 2024 Evaluation. The establishment of the Dairy G€N€ IR€LAND national breeding programme by ICBF and the partner AI companies in 2005, along with the incorporation of genomic selection in 2009, has accelerated this rate of genetic progress. The genetic improvement by each sub-index is shown in graph 2.
Graph 1. The genetic trend for EBI by year of first calving females (2002-2023).
Graph 2. The genetic improvements for the sub-indexes by year of first calving females (2002-2023).
Impact of the G€N€ IR€LAND programme
The Dairy Gene Ireland programme aims to provide dairy farmers with the highest EBI young sires through a coordinated progeny test programme. It has significantly contributed to the increase in genetic gain in the national dairy herd. All participating herds are committed to recording high levels of data, such as insemination dates, calving surveys, etc. This information collected usually forms the basis of the first proof for AI bulls and ensures these bulls achieve highly reliable proofs in as short a time frame as possible. Analysis of trends in the dairy progeny testing programme shows significant advantages in terms of reliabilities for bulls that go through Gene Ireland over those that do not. Through the efficient progeny testing of young sires, new bulls appear on the ICBF Active Bull list each year, thus giving farmers more variety to choose from while at the same time increasing the average EBI of the group, leading to increased genetic gain for farmers. The Genetic Gain delivered from G€N€ IR€LAND bulls is presented in Graph 3.
Graph 3. The average EBI, milk and fertily sub indexes of dairy bulls tested via G€N€ IR€LAND.
The average genetic merit (PTA’S) of the G€N€ Ireland bulls entering the programme between 2005 and 2023 is presented in Table 1. These genetic merit figures are taken from the March 2024 evaluation. Over this period, the average genetic merit for a kg of fat and protein has increased from 8kg in 2005 to 32 kg in 2024; this has resulted in better milk fat and protein production at the farm level. 1,138 dairy bulls have been tested through Dairy Gene Ireland, with >586,000 straws disseminated to 2,670 unique herds. These bulls have generated almost 4 million progeny on the ICBF database.
Table 1. The genetic merit for milk, fertility and Carcass weight traits of Gene Ireland bulls (2005-20204)
Genomic Technology
Genomic selection has also contributed substantially to the accelerated rate of genetic gain in EBI. Genomic selection uses DNA information to complement ancestry information and own performance data to generate a more accurate estimate of the genetic potential of an animal. The genotype of an animal (i.e. its DNA profile) impacts performance not just of the animal itself but also its progeny. Therefore, knowing the DNA profile of the calf at birth, and knowing how the DNA profile affects performance, enables prediction of the performance of that animal and its progeny.
The incorporation of DNA information into the national genetic evaluations has not only resulted in more reliable genetic evaluations at birth but also the ability to screen more animals for traits of economic interest, thereby increasing the intensity of selection and consequently genetic gain. Table 2 shows the genotyping statistics from the national genotyping programme in Spring 2024. The incidence of incorrect sire recording in Irish dairy herds is approximately 15%. This not only affects genetic gain, but can also result in mating events between animals that were thought to be unrelated. Genotyping can be used to verify parentage, and if incorrect, it can be used to assign parentage where the parents are also genotyped. DNA information can also be used to identify carriers of major genes.
Table 2. The National Genotyping programme statistics
Dairy Trend Report Statistics
A recent data analysis was completed on the trends in herd EBI, milk solids and female fertility performance from (2019 to 2023) using statistics generated from the 2023 dairy trend report on 9,424 Spring calving herds. The genetic merit of the herds are based on the number of dairy cows in the herd on the 30th June each year and are all calculated from the January 2024 evaluation, to aid with comparison between years. The analysis clearly indicates the positive impact that increasing EBI has had on the milk and fertility performance. This is illustrated in table 3. The study showed the average EBI increased steadily from €129 in 2019 to €179 in 2023. This is an increase of €50 or €100 additional profit/lactation per cow. Whilst the genetic trends clearly suggest an increase in profitability at farm level, how has the rate of genetic gain translated against actual data collected on farms.
For the fertility performance, the calving interval has improved going from 387 days down to 383 days over this period. The compactness of calving has also improved going up from 63% in 2019 to 66% in 2023. The optimum age at first calving increased by 7% and the average parity also increased from 3.1 and 3.7. In terms for the milk performance, the kg/Ms per cow increased from 443kg/per cow to 452 Kg/Ms per cows from 2019 to 2022. However, this figure decreased from to 2022 to 2023. The main reason for the decrease were due to environmental and management factors e.g. severe weather and the nitrates dairy banding. In the next article, we will discuss the impact of Herd EBI on the 2023 farm performance and how higher EBI herds are outperforming the lower EBI herds.
Table 3. Trends in herd EBI, milk solids and female fertility performance in Spring calving herds with consistently ≥30 cows over the period (2019 to 2023).
Summary
There has been substantial genetic progress achieved within the Irish Dairy herd since the introduction of Economic breeding index. Analysis has shown that EBI is selecting a more profitable and sustainable genetics for pasture based dairy systems. Gene Ireland breeding programme and Genomic selection have been key to the driving force of sustainable genetic gain nationally. However, there is still significant gains to be made by the Irish dairy industry through continued increase in EBI.