Genetic Evaluations and Breeding Goals

Genetic Evaluations are the core of Sheep Ireland’s objective as these allow farmers to compare rams from different farms based on their breeding potential and future profitability.

Sheep Ireland runs a weekly single-step across-breed genomic evaluation to help ensure breeding decisions based on ebvs are based on the most up-to-date information available at the time.

LambPlus (Performance recording) breeders can find the results of the genetic evaluations on their personal Sheep Ireland account. The genetic evaluation results for performance recorded pedigree males are also available on the Sheep Ireland Ram Search which can be found at www.ramsearch.ie

Euro-Star Evaluations

The Euro-Star evaluations is a breeding index designed to aid sheep farmers in selecting more profitable breeding animals. Euro-Star Indexs quantify the genetic component of an animal’s performance across all traits of importance for Irish sheep farmers.

Sheep Ireland Breeding Goals

Sheep Ireland was established in 2008 to implement a dynamic genetic improvement breeding programme for the Irish sheep industry and to help increase flock productivity and profitability.

Genetics exists to help commercial farmers make the most profitable breeding decisions for their particular farm management system. Animal genetics is a powerful tool that allows farmers to select superior animals to become the parents of the next generation. Genetics involves the passing on of favourable or unfavourable genes from one generation to the next. Therefore, genetics is permanent and cumulative and allows farmers to make long-term genetic gains, something that feeding or management cannot compensate for.

Breeding Goals

A breeding goal or objective describes characteristics that affect profit the most, as well as how important each trait is to profit. A breeding goal should be specific, measurable and achievable.

Breeding values are calculated from pedigree, performance data, and DNA information, using mathematical models and statistical parameters. Relevant traits are included in overall indexs and sub-indexs. The current genetic evaluations established by Sheep Ireland focus on breeding profitable animals for commercial sheep production.

The national breeding programme aims to produce a low-cost easy-care sheep, with good maternal characteristics, but that yet will produce a quality lamb with high growth rates that will reach slaughter at a young age.

Data on the traits of interest are recorded across a range of commercial and pedigree flocks and each trait is weighted based on its monetary value (€/lambs born) to farm profitability.

Overall Indexs in Sheep

1. Replacement index – ranks animals on the expected maternal performance such as number of lambs born, milk yield, lamb survival and the ease of lambing, however, it also includes some terminal traits to account for the efficiency at which animal’s progeny are finished.
2. Terminal index – ranks animals based on their ability to produce live, fast-growing terminal progeny with little lambing difficulty. This takes into account the progenies’ growth rate, carcass characteristics, days to slaughter and also lamb survival and lambing difficulty.
3. Click here for more information about Euro-Star Indexs &Traits – Sheep Ireland, and find the list of all the goal traits included in each index and the relative emphasis. Both indexes provide a measure of the genetic ability of the animal’s progeny to generate profit at a farm level for a combination of traits.

Euro-Star Ratings

The star rating system was incorporated into the Euro-Star Index to make it easier for farmers to interpret. This is the same concept used to display beef cattle evaluations in Ireland and has been largely successful in its adoption by the industry.

Within-breed stars rank an animal only against other animals within its breed, ranking each trait in 20% groupings. The higher the stars, the higher the predicted profitability from that animal within the breed in question (1 star = bottom 20%; 5 stars = top 20% of the breed).

Genetic gains

The rates of genetic gain are calculated annually for the terminal and replacement index to ensure that the genetic indexes are selecting genetically superior animals for the next generation. With the accumulation of large amounts of maternal data and continual improvement in the national genetic evaluations, there is significant scope to accelerate genetic gain across both maternal and terminal traits.

How does genetics work?

National genetic evaluations provide information to aid in selection decisions to increase the long-term performance of the national flock. The accuracy of the national genetic evaluations can be tested by comparing the genetic merit of a sire with his progeny’s performance. At high levels of accuracy, there is a large amount of data available across different management systems which results in a higher confidence level behind the breeding value. High accuracy levels will, therefore, reduce fluctuations in the published breeding values and, therefore, increase farmer’s confidence in the genetic evaluations.

Parentage information

Pedigree is based on parentage recording and DNA information. Genetic evaluations rely on the availability of accurate phenotypic information but also on the collection of pedigree or parentage information for each animal. A reliable method for the accumulation of parentage information involves the use of DNA information to retrospectively identify parents. The process involves the genotyping of all offspring and potential parents.

Genomic selection

Genomic selection is the newest breeding technology that uses genetic markers associated with genes to predict breeding values. This genetic marker information along with performance records allows for more accurate estimates of the genetic merit of the sheep. This allows young animals to achieve higher accuracy at a younger age before large amounts of information are collected on the animal, thereby, providing more accurate genetic evaluations for farmers. However, a prerequisite for a successful genomic selection programme is accurate genetic evaluations to exploit the technology.

Genetic linkage

Good genetic linkage allows for the relativity of breeding values produced between years or flocks to be established. Without genetic linkage year-to-year or flock-to-flock differences cannot be accurately accounted for in the genetic evaluations.

The fundamental mechanism of genetic evaluation is the genetic comparison of animals based on their phenotypic records and ancestry. Genetic and environmental (farm, year, sex, level of feeding) effects can be disentangled, and accuracy can reflect this.

Central Progeny Test

The CPT plays a vital role in creating genetic linkages between flocks and breeds in genetic evaluations. Information on the progeny managed in a commercial environment feeds back into the genetic evaluations and provides predictions of the genetic merit of the pedigree rams used and also his relatives, thereby, increasing accuracies.

Traits

The feasibility of breeding for any trait is dictated by the availability of data, either for the trait itself or a genetically related trait. For a trait to be included in a breeding objective it must be: 1) important (economically, socially or environmentally), 2) under genetic control, and 3) measurable or genetically correlated with a heritable trait that can be measured.

Validation

Genetic indexes, like any technology, need to deliver results on commercial farms. Genetic evaluations are a powerful tool for sheep farmers that enable them to make more informed breeding decisions and potentially increase productivity and profitability at a farm level. With the continual improvement of genetic evaluations, rapid gains can be achieved over a comparatively short time for the Irish sheep sector.

The future holds significant new possibilities for accelerated genetic improvement of the sheep population, with more productive flocks, higher lamb growth rate, requiring lower levels of assistance at lambing, reduced lamb mortality and healthier lambs and ewes. This will improve the profitability and competitiveness of the sheep industry.