USDA Genetic Evaluations for Calving Ease

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USDA Genetic Evaluations for Calving Ease
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Calving Ease Evaluations

• Objective
• Reduce calving problems during calving
  (especially first calvings)
• Procedure
• Collect reports on calving difficulty
• Calculate sire evaluations

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Frequency of Calving Difficulty
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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

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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

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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

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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 million unique calving
  reports

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Additional Data Requirements

• Single birth
• Dam and sire of Holstein or Red White breed
• Sire age gt18 mo and lt15 yr at birth of calf
• Birth date of Jan. 1, 1980, or later
• 10,195,097 records extracted

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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

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Model Definition
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Sire-MGS Model Statistics
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VC Estimates, Heritabilities, and Correlation of
Traits
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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

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