Performance Line
What to Expect with IGS ’ s New Genetic Evaluation System BOLT
By IGS Staff
Change can be a scary concept to some yet sought after by others . Many ASA members and International Genetic Solution ( IGS ) partners wonder about the changes on the horizon once BOLT is fully implemented . That change may be nerve racking but in reality , things should change . Why invest in new and improved methods if you get the same answers ? Here are key changes to expect with the new genetic evaluation :
1 . Movement of EPDs and reranking . EPDs will change especially in younger , lower accuracy cattle . Members should expect movement in lower accuracy cattle , as seen in the existing evaluations , because they may have new progeny data reported . Some cattle will move in a favorable direction while others will do the opposite . Keep in mind even if the EPDs get worse , the prediction of them is more accurate . With enough calves and phenotypes , the current evaluation would eventually arrive at a similar EPD as BOLT , it just would take longer or more information in the current system . With BOLT and the new genetic evaluation methodologies , we will have more accurate EPDs earlier in an animal ’ s life .
2 . More accurate accuracy . This idea takes a little time to sink in . The accuracy reported for each EPD will be a directly calculated and thus closer to the “ real ” accuracy . The methods to solve accuracy directly are extremely difficult and take a lot of computer power . In the current evaluation , it is not possible to solve for accuracy directly so an approximation method is used to estimate accuracy for each EPD . There are inherent flaws with approximating the accuracy which until BOLT were just part of the evaluation . Now with BOLT , the accuracy reported with the EPD will be more reliable .
3 . Reported accuracies will tend to be lower . Again , this is a little confusing at first and sounds like the opposite of what was just explained . The EPDs will be more accurate . The accuracy reported will be more accurate . Both statements are still true . However , one of the inherent flaws in the approximation methods used to find accuracy in the current evaluation , and in all evaluations not produced through BOLT , is they tend to bias the accuracies upward , especially for younger animals . This was known for a long time , but there was no way to calculate the accuracies directly . With BOLT , having accuracy directly solved results in a more reliable accuracy but that accuracy will often be numerically lower than the current evaluation would predict . However , the new reported accuracies with BOLT should better represent the possible changes for the EPDs .
4 . DNA testing will have a larger impact . With the switch to BOLT , IGS will use Single Step genomic evaluation on all EPDs ( currently using Single Step for Stayability EPDs ). Single Step uses the DNA markers , pedigree information , and phenotypic data simultaneously in the prediction of the EPDs . Previously molecular breeding values ( MBVs ) were calculated from the genomic information and those MBVs were blended separately into the EPD prediction . The Single Step method squeezes more information from the DNA markers than the previous approach allowed . Also , there are biases inherent in the blending process that aren ’ t a problem with the Single Step approach . Additionally , with Single Step , the genomic information will not only enhanced EPDs for the genotyped animal but also will be used in the EPD estimates of relatives .
5 . More frequent genetic evaluation runs . With the horse power behind BOLT , IGS can run genetic evaluations much more frequently than the current system allows . This has many benefits . It allows members to get more immediate feedback after submitting their records . If members miss a deadline , the next deadline for data won ’ t be far away . It allows for more accurate EPDs throughout the year and faster incorporation of the genomics . The down side is the EPDs put in print will quickly be outdated .
Genetic evaluation is not stagnant . There will always be improvements as new research in animal breeding , genomics , and statistics advance . BOLT is revolutionary in the innate flexibility , the computational power , and the statistical methods made possible using this software . Embrace the change to a new and improved genetic evaluation , it ’ s coming ! I
32 | FEBRUARY 2018