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Genetic Base and Trait Definition Update

Genetic Base and Trait Definition Update

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Genetic Base and Trait Definition Update

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  1. Genetic Base and Trait Definition Update

  2. Previous USA Base Changes

  3. 2005 Trait and Model Changes • Adjust for past inbreeding and expected future inbreeding (EFI) • Adjust for differing parity SD • Yield PTA expressed to average age instead of mature equivalent • Use cow instead of bull base for DPR • Convert PTA SCS to Udder Health?

  4. Genetic Gain 1995-2000(birth year)

  5. Daughter Pregnancy Rate Bases

  6. Inbreeding AdjustmentsVanRaden and Smith 1999 JDS 82:2771 • Past inbreeding (F) and future (EFI) • Regression on F in animal model (PTA0) • PTAEFI = PTA0 + EFI * byield.F • Publish PTAEFI , use PTA0 in mating program • Helps pass Interbull trend tests 2 and 3 • Corr (current PTA, PTAEFI) = .9976 • PTAEFI trend 6% lower, PTA0 trend 3% higher • Corr (USA, other countries) decline by .01

  7. Parity SD Adjustments • Multiplicative age factors • Means are adjusted to mature yield • Variances are not quite equal • Deviations will be multiplied by • [1.07 1.00 .95 .90 .85] (parities 1-5) • Helps pass Interbull trend test 1 • Corr (official, adjusted PTA) = .9998 for Holstein bulls born since 1995

  8. Adjust Yield PTA to Average Age • Average age vs. mature offsets base SD • Base SD has not been updated since 1995 • Change would multiply PTA by 1.11 (Hol) • Reduced age (36 mo) divides by 1.10 • PTA lb / EBV kg = 2.2 / 2 = 1.10 • Proposed by USDA (M. Schutz) in 1994 • Recommended by Holstein GAC, Oct 1994 • Vetoed by Council “to allow the industry time to consider the nature and effect of such a change.”

  9. Somatic Cell Count • Measured with same standard metric unit (cells / ml) in every country • Transformed by log 2, log 10, or log e • Reversed scales in 9 of 19 countries • Added means of 100, 3, 4, etc. • Changed SD to report EBV, PTA, or STA Different choice in almost every country!

  10. International Udder Health Scales

  11. SCS vs. Udder Health • PTA UH = -5 (PTA SCS – breed avg.) • Reversed scale with mean 0, SD 1 • Interpreted like linear trait STAs • Positive numbers would be favorable • Range would be similar to DPR, PL • +1 PTA UH would equal a reduction in SCC of 13% • Udder Health is an Interbull term

  12. SCS Breed Means

  13. Summary • Genetic progress in most recent 5 years similar to previous 5 years • Adjustments for inbreeding and for differing parity SD will be introduced • PTA SCS will not change to udder health • February 2005 changes must be sent to Interbull by September 1, 2004