Where next for the EBI traits
Higher EBI cows are more profitable. Donagh Berry Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, and Siobhan Ring, Irish Cattle Breeding Federation discuss improvements in EBI traits as part of the Teagasc Virtual Dairy Conference 2021 taking place today and tomorrow
- Higher EBI cows are more profitable across a range of different production systems as well as boasting a lower environmental footprint
- Possible improvements to the EBI are constantly discussed in light of likely future economic and policy changes
- Improvements include
- New traits for consideration in the EBI or updating the relative emphasis on the already existing traits
- Improvements in trait definition or underlying genetic evaluations for traits.
The EBI celebrates its twentieth year in existence this year. Irrespective of whether analyses are based on animal or herd level data from the ICBF or Teagasc eProfit Monitor, respectively, the evidence is quite clear that the EBI delivers more profitable animals; this is further substantiated by evidence from research studies at both Teagasc and UCD again demonstrating the robustness of EBI in delivering profit across a range of contrasting production systems. The modern high EBI cow is also 14% more carbon efficient per kg milk solids than the pre-EBI cow as well as being more efficient at utilising nitrogen. Nonetheless, since its introduction in 2001, the EBI has evolved both in the traits included in the index, but also their relative emphasis (Figure 1). For any further trait to be considered in the EBI it must fulfil three criteria:
- The trait must be economically, socially or environmentally important
- Genetic differences among animals must exist for the trait
- Individual animal information must exist on the trait itself or a correlated trait (for example, live-weight as an indicator of feed intake).
Key characteristics of the Irish dairy cow of the future include
(1) production of a large quantity of high-value, nutritious output (i.e., milk and meat),
(2) good reproductive performance,
(3) favourable health status,
(4) good longevity,
(5) no requirement for a large quantity of feed, yet being able to meet requirements from predominantly grazed grass (i.e., feed efficient),
(6) easy to manage (i.e., easy calving, docile),
(7) good conformation (reflective of health, reproductive performance and longevity),
(8) low environmental footprint, and
(9) resilient to external perturbations.
Figure 1. Relative emphasis on different sub-indexes within the EBI as it evolved over the last 20 years since the Relative Breeding Index (RBI)
Suites of traits of likely importance in future include:
- Environmental efficiency – both carbon emissions and nitrogen use efficiency
- Feed efficiency – ability to convert grazed pasture into products of high nutritive value
- Milk-related traits – lactation persistency and more granular measures of milk quality like caseins and milk processability characteristics
- Beef-related traits – age at slaughter and meat eating quality
- Health – a greater number of traits evaluated.
Improvements in current traits
Fertility remains a critical factor governing both economic and environmental efficiency. Calving interval as a trait in the EBI has contributed to rapid improvements in the mean reproductive performance of the Irish dairy herd. Nonetheless, recent research has demonstrated a need for more precise definitions of reproductive performance to achieve further gains, especially in high fertility herds. Research is well progressed in the development of a new fertility genetic evaluation which will improve the accuracy of the genetic evaluations and accelerate genetic gain.
As we strive to increase the number of lactations per cow, animal health is going to become more important. This is not surprising as health is generally more of an issue in elderly individuals. The extent of the contribution of differences in genetics to animal health status is much the same as exists for fertility. Therefore, breeding has a huge role to play in improving the health status of the national herd. A lack of health data, however, both in the quantity of data but also the range of traits recorded, hinders genetic gain.
Advances in technological devices including sensors but also data capture systems has the potential to address this shortcoming.
The success of EBI is conditional on adoption rate. A sire advice tool is available in the ICBF Herdplus for farmers where matings are allocated between the specified AI sires and the females in the herd; the tool maximises EBI while minimising the level of inbreeding in the resulting progeny; it also attempts to generate less extreme progeny for either milk or fertility.
Breeding involves identifying the genetically elite animals in a population and mating them (with due consideration of inbreeding); shifting the average of a population in a certain direction. Another way to shift the average of a population is to cull the least-performing animals. The ICBF generates a COW index for each female to reflect their expected remaining lifetime performance; this is used to identify cows for culling. It is complementary to the EBI and is updated as the EBI updates.
Due to updated Government guidelines the Teagasc National Dairy Conference has changed from an ‘in person’ event to being an online ‘virtual event’ only.
The Dairy Conference 2021 is on Zoom over two days. Registration gives access to both days