Data in a Genetic Evaluation – Part 1: Pedigree By Ryan Boldt, Director of Breed Improvement
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This article will be the first in a threepart series about different data types that are used in a genetic evaluation and the importance of each. For this article, the focus will be on pedigree information and why this is important in EPD calculations. This will also include some historical information, as well as how this data is incorporated into the evaluation currently. When EPDs were first being developed, they started as within-herd estimates of genetic merit. The reason being twofold: 1) the computers that were available at the time were not able to include all the pedigree relationships among animals and 2) historically, herds were not well connected to one another. The advent and increased use of AI in the seedstock industry allowed for more comparisons to be made, which in turn led to more sires being used in multiple herds, thus linking the herds together. The original models used in genetic evaluation were known as sire models that related observations to sires and fit additive relationships among sires. One disadvantage to this approach was that only animals that were used as sires were able to receive EPD values. To overcome this problem, technology advanced to create a methodology that allows for the fitting of relationships of all animals in the pedigree. This type of model is known as an animal model, and this is still the basis and type of model that is used for genetic evaluation today. In the genetic evaluation, the pedigree is important because it allows for the connection of data and information among animals. There are traits that have genetic evaluations conducted in which the phenotypes can only be recorded on one sex, like heifer pregnancy. In these situations, since
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bulls don’t have phenotypes that can be submitted, the evaluation relies on their relationships to females that have this information recorded to produce EPDs for those traits. Based on pedigree data alone, there are standard relationships that are fit based on this pedigree information. Figure 1 illustrates the relationships that are assumed among different individuals. The figure shows that as the number of generations increase, the average relationships between the individuals decrease. However, by using these relationships genetic evaluations can harness much more information on relatives of an individual to calculate the EPD values, thus allowing the EPDs to be more accurate for each individual because more information is available to make the prediction. Technology for increasing pedigree accuracy has also improved over time, specifically in the form of DNA parentage tests. These tests are now commonly run on animals’ DNA to help confirm that the pedigree is correct. The RAAA also has in its rules that any sire of a registered animal must have been confirmed to his sire before calves can be registered. This rule allows for accurate pedigree information and improves the genetic evaluation overall. This technology has been embraced by Red Angus seedstock members as the percentage of non-parent animals that have DNA submitted for parentage testing increased 160% from 2015 to 2020. This increase in use of the technology has continued to pay increased dividends for improving the accuracy of EPD information. In this example the larger percentage increase was for bulls, showing that the RAAA seedstock producers are committed to providing the best information to their commercial customers. The inclusion of pedigree information is vital to genetic evaluation. It allows for the identification of different animals, as well as helps link multiple sources of data to each animal’s EPD calculation. By doing this, it allows for EPD information that is comparable across the entire Red Angus population to allow for comparisons to be made across herds. In the next part of this series, the importance of phenotypic data collection and submission will be discussed. //
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RED ANGUS Magazine | April 2022
