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Genetic Base and Trait Definition Update

Understanding the updated genetic bases and trait definitions for improved breeding outcomes. Learn about inbreeding adjustments, parity SD, yield PTA adjustments, and more relevant changes in the genetic gain approach. Stay informed with the latest modifications in breeding protocols.

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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

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