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Genetic relationships among fertility traits of Holsteins and Jerseys (abstract 351). H.D. NORMAN * ( [email protected] , 301-504-8334 ) , R.H. MILLER, P.M. V AN RADEN, and J.R. WRIGHT Animal Improvement Programs Laboratory Agricultural Research Service, USDA

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genetic relationships among fertility traits of holsteins and jerseys abstract 351

Genetic relationships among fertility traits of Holsteins and Jerseys(abstract 351)

H.D. NORMAN* ([email protected], 301-504-8334),

R.H. MILLER, P.M. VANRADEN, and J.R. WRIGHT

Animal Improvement Programs Laboratory

Agricultural Research Service, USDA

Beltsville, MD 20705-2350

J.S. CLAY

North Carolina State University, Raleigh, NC 27603‑3435

why evaluate fertility traits
Why evaluate fertility traits?
  • Low heritability estimates but large phenotypic variation
  • High economic value
  • Decline in reproductive performance
  • Antagonistic relationship between milk yield and reproductive traits
objectives
Objectives
  • Estimate genetic relationships among fertility traits
  • Determine which reproductive traits have greatest potential use for evaluating daughter fertility of bulls
management factors
Management factors
  • Voluntary waiting period between calving and first breeding
  • Use of bST
  • Designed reproductive programs
data processing factors
Data processing factors
  • Computer program differences among dairy records processing centers
  • DHI reproduction options
  • Calving interval estimation without subsequent calving date
slide6
Data
  • 2.2 million Holstein and 0.2 million Jersey breeding records from 1995 through 2000 that included:
    • Yield (milk, fat, protein) for first 3 test days
    • Identification (service sire, cow, sire, dam)
    • DIM at each service
    • Parity
  • DHI herds with records processed by:
    • AgriTech Analytics
    • AgSource Cooperative Sources
    • Dairy Records Management Systems
    • Pennsylvania DHI Association
data restrictions
Data restrictions
  • <150 DIM at third test day
  • Daily milk yield between 4.5 and 109 kg
  • Test-day component percentage between 2.0 and 8.0
  • Fat and protein percentages reported for at least 2 of first 3 test days
fertility traits
Fertility traits
  • Days from calving to first service
  • Days from calving to last reported service (days open)
  • Nonreturn to first service within 70 d (nonreturn rate)
  • Number of services
fertility restrictions
Fertility restrictions
  • Successful breeding if cow not reported in estrus or rebred within 70 d
  • Breedings excluded:
    • Virgin heifers
    • <15 or >365 DIM
    • Cows that left herd <70 d after first service
    • Subsequent breedings within 4 d
    • Non-AI first services
  • Herd:
    • >9 AI matings annually
    • >9 or <90% for annual mean for nonreturn rate
analysis
Analysis
  • Fertility traits adjusted for:
    • Parity (fixed; 1, 2, … 5, 5+)
    • Age deviation within parity (linear regression)
    • 2 highest test-day yields (linear regression):
      • Milk
      • Fat
      • Protein
    • Lactation stage at first service (nonreturn rate and number of services only)
analysis continued
Analysis (continued)
  • Heritabilities and genetic correlations estimated with multitrait REML sire model:
    • Observations from 1998 to 2000
    • 3447 Holstein bulls with 40 daughters
    • 2602 Jersey bulls
conclusions
Conclusions
  • Days open has higher heritability than nonreturn rate
  • Days open has moderate to high genetic correlation with days to first service and number of services
  • Days open appears to be best single measure among fertility traits examined for genetic evaluation of cow fertility
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