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USDA Genetic Evaluations for Calving Ease

USDA Genetic Evaluations for Calving Ease

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USDA Genetic Evaluations for Calving Ease

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  1. USDA Genetic Evaluations for Calving Ease

  2. Calving Ease Evaluations • Objective: • Reduce calving problems during calving (especially first calvings) • Procedure: • Collect reports on calving difficulty • Calculate sire evaluations

  3. Calving Ease Scores 1 = No problem during calving or calving not observed 2 = Slight problem during calving 3 = Cow needed assistance during calving 4 = Considerable force used during calving 5 = Extreme difficulty during calving

  4. Frequency of Calving Difficulty Source: K. A. Weigel, 2002

  5. History 1977 – NAAB-sponsored evaluations within AI organizations 1980 – NAAB-sponsored evaluations across AI organizations 1988 – Ordered categorical threshold model 1990 – Semiannual evaluations 1999 – Processing change from Iowa State University to USDA (November) 2002 – Sire-maternal grandsire (MGS) model

  6. Sire – MGS Project Improved Data • Enhanced detection of duplicate calving reports • Use of animal key to deal with identification changes • Database maintenance to allow easy update and access • Access to pedigree from production evaluations to increase data accuracy and provide missing MGS information

  7. Sire – MGS Project Improved Model • MGS effect added • Evaluations of bulls as service sires improved by partially accounting for mates • Maternal effect on calving difficulty provided

  8. Data • Over 10 million calving reports since 1980 • In addition to pedigree data for production evaluations, almost 2.5 million pedigree records for cows without unique national identification • Allows data to be included that does not meet requirements for production

  9. Data Extraction Requirements • Single birth • Dam and sire of Holstein or Red & White breed • Sire age >18 mo and <15 yr at birth of calf • Birth date of Jan. 1, 1980, or later 9,772,473 records extracted

  10. Observed scores 1 2 3 4 5 1 Underlying scale 5 Threshold model • Scores assumed to be observations on a continuous underlying scale • Thresholds estimated to relate observed scores to underlying scale • Procedure allows for differences in amount of change between consecutive scores

  11. Calving Ease Evaluation Statistics(Sire-MGS Model)

  12. Presentation of Evaluations • Evaluations converted to expected percentage of births that would be scored 4 or 5 (difficult) for heifers (%DBH) • Most frequent %DBH was 8%

  13. %DBH distributions 10,000 Number of sires 7,500 New system 5,000 Previous system 2,500 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 %DBH

  14. Status of Evaluation System • Test evaluations distributed to AI organizations • Web queries to display calving ease data under review • First release of sire-MGS evaluations for calving ease planned for August 2002