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Selection Differentials from National Holstein Bull Progeny Test Programs Estimated from International Data. Characteristics of Ideal Progeny Test Program. High pedigree merit Large number of bulls Rapid and accurate evaluation Large number of daughters/herds Intensive culling. Objective.

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Selection Differentials from National Holstein Bull Progeny Test Programs Estimated from International Data


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Characteristics of Ideal Progeny Test Program Test Programs Estimated from International Data

  • High pedigree merit

  • Large number of bulls

  • Rapid and accurate evaluation

    • Large number of daughters/herds

  • Intensive culling


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Objective Test Programs Estimated from International Data

  • Document characteristics of national progeny test (PT) programs

    • Age of bulls at decision

    • Percent of bulls retained

    • Standardized selection differentials

      (selection intensities)

  • Compare PT strategies of different countries


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Comparison Considerations Test Programs Estimated from International Data

  • Many factors affect PT program quality

  • Complex relations between factors

    A country may have higher pedigree requirement, but return more bulls to service and have a lower selection differential.


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Data Test Programs Estimated from International Data

  • Holstein Interbull evaluations

  • PT decisions February 1996 - 1998

  • Eleven countries with at least 125 PT bulls over this period


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Assumptions Test Programs Estimated from International Data

  • PT decision made on second evaluation

    provided by Interbull

  • Country of PT was country with most daughters in decision evaluation

  • Returned to service if 200 daughters added in country of PT from evaluations 2.5 to 4.5 years after PT decision


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Numbers of Bulls Test Programs Estimated from International Data


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Numbers of Bulls Test Programs Estimated from International Data


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Numbers of Bulls Test Programs Estimated from International Data


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Herds, Daughters, and Reliabilities Test Programs Estimated from International Data


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Herds, Daughters, and Reliabilities Test Programs Estimated from International Data


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Herds, Daughters, and Reliabilities Test Programs Estimated from International Data


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Selection Intensities Test Programs Estimated from International Data


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Selection Intensities Test Programs Estimated from International Data


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Selection Intensities Test Programs Estimated from International Data


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Conclusions Test Programs Estimated from International Data

  • Reliability at PT decision time: 80-92%

  • Mean bull age by country: 66-77 months

  • PT bulls return to service by country: 3.4-15.6% (Mean 6.9)

  • Selection intensities: .33-1.64

    (Tended ~1)

  • Highest selection intensities were for protein in all 11 countries


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