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CGs to EPDs

CGs to EPDs. 2006 BIF Symposium Sponsored by Ultrasound Guidelines Council Dr. Lisa A. Kriese-Anderson Auburn University. Would you purchase a bull …. Would you purchase a bull …. This top young son of Superbull had a weaning weight of 636 lbs. Would you purchase a bull ….

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CGs to EPDs

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  1. CGs to EPDs 2006 BIF SymposiumSponsored by Ultrasound Guidelines Council Dr. Lisa A. Kriese-AndersonAuburn University

  2. Would you purchase a bull ….

  3. Would you purchase a bull …. This top young son of Superbull had a weaning weight of 636 lbs

  4. Would you purchase a bull …. An exceptional prospect with a scrotal circumference of 35 cm This top young son of Superbull had a weaning weight of 636 lbs

  5. So, why would you consider….

  6. So, why would you consider…

  7. So, why would you consider…

  8. Ultrasound Basics • Individual ultrasound measurements (adjusted) are as useful as individual weights and measures • Really only mean something within the group they came from • Ratios are better • EPDs for ultrasound or carcass are best for selection decisions

  9. Ultrasound Genetics Refresher • Ultrasound measurements should be taken the same time as yearling weights • Generally 320/330 to 410/430 days of age • BIF says 335 to 395 days • Entire contemporary group should be measured by a certified ultrasound technician • Genetically, ultrasound measurements for carcass traits are highly correlated to actual carcass traits • But they are not the same traits

  10. Ultrasound Genetics Refresher

  11. Ultrasound Genetics Refresher Reminder – if you do not report any carcass data, individual animal accuracy can only be a high as the genetic correlation

  12. Genetic EvaluationBegins withP = G + E

  13. In Genetic EvaluationE ≈ Contemporary Group

  14. Contemporary Group • A contemporary group is a group of animals with the same: • Herd • Sex • Birth Season • Weigh date • Management • The largest contemporary group is at birth. All subsequent traits are subsets of the birth contemporary group.

  15. In Simplest Terms: • BV = h2 x SD • SD = Selection DifferentialSD = (individual – avg of group)

  16. Example Data

  17. Data Analysis • Multiple-trait animal model • WW, PWG, UREA, UBF, %IMF in analysis • Examine Sire Rankings for above traits

  18. Sire EPD Rankings

  19. Example Data – Just 1 CG

  20. With Wrong CG Definitions • Do not have correct comparisons in data • Sires are compared in “head to head” competition that were not • Basics of EPD analysis is to find the group average and subtract the individual measurement from it • Group mean is wrong!

  21. Comparing Sire Ranks – Wrong CG

  22. Not Reporting All Data

  23. By Not Reporting All Data • If not sending in “bottom-performing” cattle, penalize the rest • Group means are incorrect once again • Competition is not reported accurately

  24. By Not Reporting All Data

  25. Sire EPD Ranks – Incomplete Data

  26. Not Reporting All Data

  27. Sire EPD Ranks – Incomplete Data

  28. Final Comments • Actual ultrasound data needs to be treated the same as actual data from any other trait • Must be in a comparison mode (Ratio/EPD) • For use within a contemporary group • May be helpful to divide data into thirds • Always remember there can be measurement error. Don’t believe in absolutes

  29. Field Certification

  30. Final Comments • Proper reporting of contemporary groups is essential • P = G + E is the basis for all genetic evaluation • Don’t selectively report data • Only penalizing the top animals • Only hurting yourself • Don’t let a trait you may not be able to visualize well keep you from doing the right thing

  31. Additional Items • If a breed publishes both ultrasound and carcass EPD values, want ultrasound and carcass EPDs to be similar:

  32. Additional Items • If breed published just carcass and you collect/report no carcass info, accuracy will only be as high as genetic correlation • Don’t single trait select!

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