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USDA Genetic Evaluations for Calving Ease

USDA Genetic Evaluations for Calving Ease. Calving Ease Evaluations. Objective: Reduce calving problems during calving (especially first calvings) Procedure: Collect reports on calving difficulty Calculate sire evaluations. Frequency of Calving Difficulty. History.

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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. Frequency of Calving Difficulty

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

  5. 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

  6. 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 included in MGS effect

  7. Data • Over 11 million calving reports since 1980 • Pedigrees matched to production evaluation pedigree database • 2.5 million pedigree records for cows without unique national identification also included • Improved edits yield 10.5 millionunique calving reports

  8. Additional Data 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 10,195,097 records extracted

  9. 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

  10. Model Definition

  11. Sire-MGS Model Statistics

  12. VC Estimates, Heritabilities, and Correlation of Traits

  13. Presentation of Evaluations • Evaluations converted to expected percentage of difficult (scored 4 or 5) births for heifers (%DBH) • Most frequent %DBH was 8% • Genetic Base • Daughter CE – MGS born in 1990 • Service sire CE - sires born in 1995 • %DBH for MGS relatively constant • %DBH for sires increasing

  14. Calving Ease Trends 1456 1541 1025 1486 921 916 1061 1545 1477 112

  15. Status of Evaluation System • Sire-MGS evaluations for CE released in August 2002 • Web queries to display CE data available to participants • Daughter CE may be included in future index calculations

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