available information from the DNA in the form of an MBV. Because DNA can be collected and analysed at a young age, this provides the power to improve accuracy of the evaluation at a young age. To paraphrase, DNA provides us with a lot of additional data that can be analyzed at a young age. A simplified example is shown below. Animal Blended Acc Bull A 30 Bull B 30 Bull C 50
WW
Acc
MBV Blended WW
0.80 0.10 0.30
50 50 50
31 40 50
0.80 0.25 0.35
In this example, based on the accuracy of the EPD, we can see that Bull A has a lot of data available on his progeny. The DNA information does not contribute significantly to his EPD. Bull B with low accuracy, sees a significant shift in his EPD, since the DNA provides a significant amount of new information that moves his EPD upward and increases the accuracy. Bull C does not see his EPD change at all, but the addition of DNA to his evaluation increases the accuracy or certainty of our prediction of his genetic merit. The impact of DNA on individual traits will depend on the heritability of the trait, the relative strength of the relationship between available DNA markers and the trait in question and the amount of additional data, such as performance records available. Enter Single Step The latest development in genetic evaluation is called single step and it connects DNA and evaluation in a very real way. Instead of “blending” or combining DNA and EPD information after the fact, single step uses DNA as an additional source of data in the genetic evaluation, just as pedigree and performance data are used. Just as moving to the animal model of EPD calculation, single step evaluation has required a quantum leap in computing horsepower. If we think about the move from sire/MGS models to animal models moving from 7 to 14 animals in a 3 generation pedigree, consider that a single DNA test, on a single animal can easily add 50,000 DNA markers. That is 49,997 more pieces of information to analyze on an animal than a birth, weaning and yearling weight. Additionally, single step analysis can allow us to use that DNA to improve pedigree relationships. If for example a sire and a son have both been tested, it is now possible to see which pieces of DNA were passed on, rather than just assuming that a random half of a calf’s genetic makeup came from a parent. In other words, some siblings are more closely related than others. This strengthens the traditional pedigree/
performance aspect of the evaluation, but it also empowers the DNA trait analysis because it allows for consideration of the impact of specific markers on a trait throughout the entire pedigree tree, rather than applying a simplified adjustment after an EPD evaluation. The single step approach also helps to identify and correct potential pedigree information on the fly. The new system adopted by the CSA that uses single step calculation is called BOLT (short for Biometric Open Language Tools). This is a fancy way to say that the hardware and software that makes up BOLT is the 600 horsepower, GPS/autosteer equipped, four-wheel drive tractor with overlap control of the genetic evaluation world. Like previous advancements in genetic evaluation technologies, BOLT will not result in massive reranking of animals, but it will provide a much more robust picture of where animals fit relative to each other, and it also provides the framework to evaluate new traits much more effectively, similar to the way the animal model enhanced the evaluation of maternally influenced traits. I am certain based on history and some knowledge of the work that is ongoing at the moment, that over time we will continue to see improvements in genetic evaluation. Some will come gradually, and others will be of the transformational variety. Genetic evaluation technology is being applied in most, if not all of the biological breeding industries including plants and animals and will continue to assist in decision making to enhance profitability and functionality of beef cattle.
EPD Theory / Methodology Pre-1970
Herdbook
1970-1980s
Performance Data Collection/Reporting
Early 1990s
Sire/MGS EPD Evaluation
Mid 1990s
Animal Model EPD Evaluation
2010-2016
Blended EPD
2016-2017
Single Step Evaluation – Incorporates Traditional Evaluation and DNA Information Directly
Single Trait DNA Testing
MBV
DNA SNP testing
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