Notes
Slide Show
Outline
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Effectiveness of genetic evaluations in predicting daughter performance in individual herds
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Background
  • Response to genetic selection has been well documented on a population basis


  • Dairy producers are more likely to appreciate its value if it is demonstrated in their own herd


  • Prediction on an individual herd level should be a useful extension tool
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Data
  • First lactation cows calving from 2005-2008
    • Required to have both sire and dam PTAs
    • Matched cow’s phenotypic record with sire and dam PTA from evaluation prior to cow’s first calving
  • Herds with a minimum of 50 cows meeting above criteria
  • 7,697 Holstein herds; 412 Jersey herds
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Prediction model – ran for each herd
  • Phenotypic trait=
      • Parent Average of same trait
      • + cow’s calving yr
      • + Error


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Traits predicted:

      • 1st lactation ME Milk
      • 1st lactation ME Fat
      • 1st lactation ME Protein
      • 1st lactation ME SCS
      • Days open  (using PTA DPR * -4)
      • Productive life (PL)

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Individual herd regression (b) - Holstein
    • Trait Mean and SD of b
    • 1st lactation ME Milk 1.01 ± 0.45
    • 1st lactation ME Fat 0.90 ± 0.44
    • 1st lactation ME Protein 0.81 ± 0.43
    • 1st lactation ME SCS 0.88 ± 0.60
    • 1st lactation Days open 1.03 ± 1.10
    • Productive Life 0.71 ± 0.69

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Individual herd regression (b) - Jersey
    • Trait Mean and SD of b
    • 1st lactation ME Milk 1.02 ± 0.42
    • 1st lactation ME Fat 0.91 ± 0.39
    • 1st lactation ME Protein 0.91 ± 0.43
    • 1st lactation ME SCS 0.86 ± 0.69
    • 1st lactation Days open 1.03 ± 1.12
    • Productive Life 0.69 ± 0.80

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Distribution of regressions (b) - Holstein
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Distribution of regressions (b) - Jersey
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Why herds might show different progress than expected
  • Too few records to show an accurate picture
  • Different management level
  • Misidentification
  • Predicting 1st lactation phenotypes, based on PA calculated from lactations 1-5
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Mean regressions (b) from predicting 1st lactation traits from PA by number of cows - Holstein
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Standard deviations of the regressions (b) from predicting 1st lactation traits from PA by number of cows - Holstein
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Mean regressions (b) from predicting 1st lactation traits from PA by number of cows - Jersey
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Standard deviations of the regressions (b) from predicting 1st lactation traits from PA by number of cows - Jersey
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Mean regressions (b) from predicting 1st lactation traits from PA by production level - Holstein
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Standard deviations of the regressions (b) from predicting 1st lactation traits from PA by production level - Holstein
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Mean regressions (b) from predicting 1st lactation traits from PA by production level - Jersey
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Standard deviations of the regressions (b) from predicting 1st lactation traits from PA by production level - Jersey
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Conclusions
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