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Docility EPD: A Tool for Temperament
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  1. Docility EPD: A Tool for Temperament Devori W. Beckman Iowa State University 2007 NBCEC Brown Bagger Series October 24, 2007

  2. What is Docility? • Temperament – reaction of beef cattle to handling by humans (Burrow, 1997) • Why Measure Docility? • Ease of Handling • ADG • Carcass Quality • RFI

  3. Measuring Docility • Flight Speed/Time, Exit Velocity • Pen Score, Docility Test, Separation Test • Chute/Crush Score

  4. Scoring System Docile Aggressive BIF Guidelines (2002)

  5. Docility EPD: Breed Associations • North American Limousin Foundation (NALF) • 1st Genetic Evaluation in 1998 • Scores allocated at weaning • Threshold (1, 2, 3-6); h2 = 0.40 • American Angus Association (AAA) • Genetic Evaluation Spring 2008 • Scores allocated at yearling • Threshold (1, 2, 3, 4-6); h2 = 0.37 Kuehn et al. (1998); Hyde (2003); Northcutt (2007)

  6. Docility EPD: Sire Comparison Example

  7. Maternal (M) Effects on Docility Sire by Herd (SH) Effects Further Investigation of M and SH Effects Genetic Parameter Estimates For Docility In Limousin Cattle

  8. Recent Work: Maternal Effects Beckman et al. (2007)

  9. Recent Work: Sire × Herd Notter et al. (1992); CSU - Unpublished Data

  10. Objective • Do Maternal or SH effects appropriately describe docility, or are they artifacts of the nature of this data.

  11. Previous Models Assumed Homogeneity Beckman et al. (2007)

  12. Additional Data Filtration

  13. Additional Data Filtration

  14. Assessment of Heterogeneity • Step 1: Mixed Model (BASE) Analysis

  15. Assessment of Heterogeneity • Step 2: Fixed Model

  16. Results: Fixed Model Beckman and Garrick (2007)

  17. Variance Component Estimation • Mixed Model (RESID) Analysis |ê| = Xb + ZDuD + ZMuM + ZSHuSH + e

  18. Results: Variance Components Beckman and Garrick (2007)

  19. Results: Variance Due to Herd

  20. Conclusions • Maternal and SH Interaction Effects were Artifacts of the Data • Most of Heterogeneity Due to Herd Effects

  21. Implications • Accuracy of Genetic Evaluation • Total Herd Reporting Garrick and Van Vleck (1987)

  22. What’s Next? • Further Investigation of Heterogeneity • Clustering of Herds

  23. Acknowledgements • North American Limousin Foundation • American Angus Association • Colorado State University • Iowa State University Thank you!

  24. Image from schooldiscovery.com