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RESULTS (cont.) Deviation in NR70 for interactions of service sire with cow sire (>25 first services/combination) Pa PowerPoint Presentation
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Abstr. M11. Contribution of inbreeding and recessive defects to early embryo loss P.M. VanRaden and R.H. Miller* Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350. INTRODUCTION

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Abstr. M11

Contribution of inbreeding and recessive defects to early embryo loss

P.M. VanRaden and R.H. Miller*

Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350

INTRODUCTION

  • Reproductive traits adversely affected by inbreeding because of large nonadditive genetic variance
  • Recent interest in crossbreeding because of declining female reproductive efficiency
  • Recessive genetic defects that cause embryonic death expressed as complete dominance and add to fraction of nonadditive genetic variance
    • Complex vertebral malformation (CVM)

Swedish Holstein carrier bulls had lower 168-d nonreturn rates; no difference for 28- and 56-d nonreturn rates

(Persson, 2003, Undergraduate Thesis, Swedish Agric. Univ., Uppsala)

    • Deficiency of uridine monophosphate synthase (DUMPS)
  • Probability that mates will be carriers for same genetic defect increased by inbreeding

METHODS

  • Model included herd-year-season, cow parity, cow sire, service sire, regression on inbreeding, and interaction of service sire and cow sire
    • Service sire effects constant and uncorrelated across time
    • Additive relationship matrix for cow sire
    • Dominance relationship matrix for interaction
    • Additive ×additive effects not included
  • Variance estimation (Hoeschele, 1991, J. Dairy Sci. 74:1743)
    • REML for main effects and data adjusted
    • Tilde-hat REML approximation for interaction effect
  • Analysis to determine if bull CVM and DUMPS status explained variation in interaction effect

RESULTS (cont.)

  • Deviation in NR70 for interactions of service sire with cow sire (>25 first services/combination)
  • Paradise-R Cleitus Mathie
    • Maximum number of matings to own daughters (154)
    • Maximum frequency for individual CVM carrier carrier combinations (792 with Highlight Mr Mark Cinder)
    • Included in 5 of the 10 most frequent CVM carrier  carrier combinations

RESULTS

  • Regression of NR70 on inbreeding of embryo was

–0.096 per 1% increase in inbreeding, which could be explained by fatal defects in >20% of embryos

  • 348 bulls mated to own daughters
  • Variation
    • Service sire: 0.36%
    • Cow sire: 0.24% (heritability of 1.0%)
    • Interaction: 0.18% (dominance variance of 2.8%)
  • Interaction of service sire with cow sire
    • Total of 369,017 bull combinations
    • Mean of 6 records per bull combination
    • 50 bull pairs with>500 records (maximum of 2077) and reliability of >50%
    • Estimates (compared to mean NR70 of 56%)
      • Including inbreeding effect: –3.6 to 2.9%
      • Excluding inbreeding effect: –3.2 to 3.5%
  • CVM/DUMPS status
    • 2195 combinations included 2 known CVM carriers
    • No indication that CVM or DUMPS status explained variation in NR70

OBJECTIVES

  • Using 70-d nonreturn rate (NR70) as a measure of reproduction, determine
    • Magnitude of nonadditive genetic variance
    • Effects of inbreeding
    • Extent that recessive genetic defects contribute to nonadditive variance

DATA

  • NR70 based on 1.74 million first AI services of US Holsteins from 1995 through 2000
  • All dairy records processing centers represented except DHI-Provo
  • 1,251 bulls included as cow sire or service sire
    • >100 daughters for cow sires
    • >500 first services for service sires
  • Genotyping results to determine bull CVM and DUMPS carrier status

DATA

  • NR70 based on 1.74 million first AI services of US Holsteins from 1995 through 2000
  • All dairy records processing centers represented except DHI-Provo
  • 1,251 bulls included as cow sire or service sire
    • >100 daughters for cow sires
    • >500 first services for service sires
  • Genotyping results to determine bull CVM and DUMPS carrier status

CONCLUSIONS

  • Substantial negative impact from increased embryo inbreeding on conception and 70-d survival after insemination
  • Substantial dominance variance for NR70 (nearly 3 times larger than additive variance)
  • Variation in NR70 not related to status of service sire or cow sire for CVM (losses later in gestation) or DUMPS (few carrier bulls)
  • Investigation of embryo loss later in gestation needed to determine impact of bull CVM status