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Properties of International Longevity Evaluations and Correlations with Other Traits

Properties of International Longevity Evaluations and Correlations with Other Traits. Longevity Challenges. Improve the exchanged statistical parameters Match EDC and heritability to better reflect reliability from different models Are trait definitions consistent?

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Properties of International Longevity Evaluations and Correlations with Other Traits

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  1. Properties of International Longevity Evaluations and Correlations with Other Traits

  2. Longevity Challenges • Improve the exchanged statistical parameters • Match EDC and heritability to better reflect reliability from different models • Are trait definitions consistent? • Correlations of longevity with other traits on each nation’s scale • Adjustment for yield traits • Genetic trends (correlation with birth year)

  3. Effective Daughter Contributions • 1 EDC = 1 daughter if no censoring • EDC should be reduced for recent birth years due to censoring • Use number of culled daughters, or • Use squared correlation of partial with final longevity (DEU, ISR, USA), or • Use multi-trait EDC formulas for partial longevity traits (CAN and NZL)

  4. Problems in Defining EDC • With binomial traits, observed daughters should contribute EDC, not just culled daughters • If daughters had opportunity to be culled but none were culled yet, EDC should be > 0 • Accurate EDC are more important for traits with low REL

  5. Heritabilities • Wide range (.02 to .20) • Genetic correlations and SD may be sensitive to incorrect estimates • Single-trait vs multi-trait EDC formulas across lactations (CAN, NZL) • Log scale (DEU) vs observed scale. Is transformation to observed scale accurate?

  6. Data • Bulls born 1985-1994 in MACE longevity file (van der Linde and de Jong, 2002) • Only data on “home country” scale (country with the most daughters) • Yield, SCS, and conformation evaluations from Interbull (Feb 2002) • Some scales reversed to make positive always desirable for longevity and undesirable for SCS

  7. Correlations of Direct Longevity with SCS and Conformation

  8. Correlations of Direct Longevity with Yield Traits

  9. Percentage of 2nd Crop Bulls

  10. Conclusions • Correlations of longevity with SCS and conformation traits were fairly uniform across countries • Yield correlations with functional and with true longevity both varied across countries • Improved definitions of EDC and heritability are suggested

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